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General Discussion => Advanced Concepts => Topic started by: Greg Hullender on 06/21/2014 09:04 pm

Title: Solar Power Satellites
Post by: Greg Hullender on 06/21/2014 09:04 pm
If Japan really decides to build one or more 10,000-ton solar power farms, that would provide business for lots of launches.

http://spectrum.ieee.org/green-tech/solar/how-japan-plans-to-build-an-orbital-solar-farm

The IEEE article includes lots of reasons why this may never get off the ground, of course, but it's interesting to think about what sort of economies of scale might be possible given projects like this. And what sort of projects might be possible given further reductions in price.
Title: Re: Solar Power Satellites
Post by: Lar on 06/22/2014 05:40 am
This article was mentioned already in the  SpaceX advances drive for Mars rocket via Raptor power thread

http://forum.nasaspaceflight.com/index.php?topic=34197.msg1192997#msg1192997 

Interested readers may want to review the post I referenced and some of the posts immediately after.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 06/22/2014 08:21 am
They have a long way to go to compete with terrestrial solar power but there some technologies in pipeline to make it more viable.

SpaceX BFR if it us fully reusable.
Tethers Unlimited SpiderFab.
Increasing Watts/ kg of solar panels.

Japan has talked about beaming power from moon to earth but actually sending power to lunar base from SSP satellite or even earth may be ideal for supplying power 24/7.
Title: Re: Solar Power Satellites
Post by: cordwainer on 06/23/2014 01:56 am
Unlike, Musk I think the conversion rates can be made efficient enough for this to be physically practical.  What makes it difficult is the initial cost in infrastructure which makes it non-competitive over other forms of power though. I think fusion research has a better chance in the short term of creating results than all the things that would have to come together to make space based solar power economical.

On a positive note you might be able to increase the efficiency of your microwave rectenna by using photonic crystals to tune the incoming microwaves for better absorption. You could also put your rectenna on a ground tethered high altitude dirigible to lower losses and prevent communication interference posed by beaming through the lower atmosphere.
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/26/2014 11:05 am
On a positive note you might be able to increase the efficiency of your microwave rectenna by using photonic crystals to tune the incoming microwaves for better absorption. You could also put your rectenna on a ground tethered high altitude dirigible to lower losses and prevent communication interference posed by beaming through the lower atmosphere.
85% efficient rectennas (5.8GHz) have already been demonstrated in the lab. The way to improve further is to eliminate the schottky diode losses by using synchronous rectification and impedance matching for maximum power transfer.

Beam power losses through the atmosphere are less than 2% for 99% of all weather (including "very cloudy and severe rain" [Kantak, JPL, 2003]). Given that the rectenna needs to be at-least 4.5km across (for 5.8GHz) to meet the diffraction limit of a 1km satellite antenna located at GEO, I'm afraid the prospect of floating it is slim (and unnecessary).

5.8GHz is one of the ISM bands (industrial, scientific & medical), as-is 2.4GHz wi-fi. Interference is possible, but would be confined to the vicinity of the rectenna and the frequency band. Peak beam intensity for most proposals is kept below 300W/m2 (about 1/4 to 1/3 mid-day sun), a level safe for birds, bees and aircraft to fly through.
Title: Re: Solar Power Satellites
Post by: Nomadd on 06/26/2014 11:10 am
On a positive note you might be able to increase the efficiency of your microwave rectenna by using photonic crystals to tune the incoming microwaves for better absorption. You could also put your rectenna on a ground tethered high altitude dirigible to lower losses and prevent communication interference posed by beaming through the lower atmosphere.
85% efficient rectennas (5.8GHz) have already been demonstrated in the lab. The way to improve further is to eliminate the schottky diode losses by using synchronous rectification and impedance matching for maximum power transfer.

Beam power losses through the atmosphere are less than 2% for 99% of all weather (including "very cloudy and severe rain" [Kantak, JPL, 2003]). Given that the rectenna needs to be at-least 4.5km across (for 5.8GHz) to meet the diffraction limit of a 1km satellite antenna located at GEO, I'm afraid the prospect of floating it is slim (and unnecessary).

5.8GHz is one of the ISM bands (industrial, scientific & medical), as-is 2.4GHz wi-fi. Interference is possible, but would be confined to the vicinity of the rectenna and the frequency band. Peak beam intensity for most proposals is kept below 300W/m2 (about 1/4 to 1/3 mid-day sun), a level safe for birds, bees and aircraft to fly through.
85% efficient over what distance?
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/26/2014 11:37 am
85% efficient over what distance?
Good question!

That is the efficiency for converting the incident beam power falling within the confines of the rectenna.

84% of the beam power is confined within a circular region called the "Airy disk" (George Biddell Airy), which dictates the minimum size of the rectenna and transmit antenna for a given frequency and beam path length. A larger rectenna would capture more of the beam, and could operate away from the equatorial band, e.g. a 12km rectenna could capture 88.5% of the beam power arriving at 20 degrees elevation, or 94.7% from directly overhead.

Other losses are at the satellite-end of the beam and include:

PV efficiency - 40% expected from multi-junction concentrated cells (44.7% demonstrated)
                    -  20% --> >50% expected from future thin-film (e.g. perovskite research, 19% demonstrated)
                    -  bear in-mind that earth-orbit solar flux is 57% greater than equatorial mid-day terrestrial sun, for 24/365.
PMAD (Power Management and Distribution)
                    - early (and some recent) proposals transport electrical power over multi-kilometre distances (from PV cells to microwave generators) and across rotating joints. Peter Glaser's (RIP 2014) original proposal required liquid helium-cooled superconductors.
                     - modern PMADs use "sandwich panel" concepts with distribution distances measured in cm
                     - overall conversion efficiency (electrical --> microwave) could achieve >70%
Title: Re: Solar Power Satellites
Post by: floss on 06/29/2014 01:16 am
Beaming power to earth is a pretty non starter (efficency of energy transfer) but using large solar plants to power antimater factories seems plausable .

Plus this would usher in the antimater era and give humanity the stars .
Title: Re: Solar Power Satellites
Post by: mheney on 06/29/2014 01:54 am
Beaming power to earth is a pretty non starter (efficency of energy transfer) but using large solar plants to power antimater factories seems plausable .

Plus this would usher in the antimater era and give humanity the stars .


I'm not sure you can say that transmission losses (a well-understood problem) makes a concept a non-starter, but then turn around and call antimatter factories is a plausible alternative...
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 06/29/2014 06:32 am
Japan plan to test power beaming in next few years by fitting a transmitter to ISS. With 300kw on tap it makes a great test bed.
Title: Re: Solar Power Satellites
Post by: floss on 06/29/2014 11:03 am
Beaming power to earth is a pretty non starter (efficency of energy transfer) but using large solar plants to power antimater factories seems plausable .

Plus this would usher in the antimater era and give humanity the stars .


I'm not sure you can say that transmission losses (a well-understood problem) makes a concept a non-starter, but then turn around and call antimatter factories is a plausible alternative...



Just one alternative the fact is that every environmentalist will be up in arms and the building of anything that shoots death rays at earth will have a leagle minefield before it is built .
If the power is used to produce antimatter it would be of great benefit to humanity as a whole and the SSP need not be in Earth Orbit.
I know that initially Antimatter production would be brutally inefficent seeing as none has yet been built yet but we are talking about centuries of upgrades.

Producing power from off world is going to have massive startup costs and there is plenty of resorces on Earth humanity is only tapping the tip of the iceburg so far .

Plus the first Antimatter factory be a high risk effort and it would be handy to put it far away from Earth in case of accidents.






Title: Re: Solar Power Satellites
Post by: Tass on 06/29/2014 01:12 pm
Beaming power to earth is a pretty non starter (efficency of energy transfer) but using large solar plants to power antimater factories seems plausable .

Plus this would usher in the antimater era and give humanity the stars .


I'm not sure you can say that transmission losses (a well-understood problem) makes a concept a non-starter, but then turn around and call antimatter factories is a plausible alternative...



Just one alternative the fact is that every environmentalist will be up in arms and the building of anything that shoots death rays at earth will have a leagle minefield before it is built .
If the power is used to produce antimatter it would be of great benefit to humanity as a whole and the SSP need not be in Earth Orbit.
I know that initially Antimatter production would be brutally inefficent seeing as none has yet been built yet but we are talking about centuries of upgrades.

Producing power from off world is going to have massive startup costs and there is plenty of resorces on Earth humanity is only tapping the tip of the iceburg so far .

Plus the first Antimatter factory be a high risk effort and it would be handy to put it far away from Earth in case of accidents.

Sending a ray down with the same intensity as sunlight, and which will defocus harmlessly if the pilot signal is interrupted, will have the environmentalists "up in arms", but shipping down packages of power which will explode like a nuke if containment fails, won't?
Title: Re: Solar Power Satellites
Post by: floss on 06/29/2014 01:52 pm
Beaming power to earth is a pretty non starter (efficency of energy transfer) but using large solar plants to power antimater factories seems plausable .

Plus this would usher in the antimater era and give humanity the stars .


I'm not sure you can say that transmission losses (a well-understood problem) makes a concept a non-starter, but then turn around and call antimatter factories is a plausible alternative...



Just one alternative the fact is that every environmentalist will be up in arms and the building of anything that shoots death rays at earth will have a leagle minefield before it is built .
If the power is used to produce antimatter it would be of great benefit to humanity as a whole and the SSP need not be in Earth Orbit.
I know that initially Antimatter production would be brutally inefficent seeing as none has yet been built yet but we are talking about centuries of upgrades.

Producing power from off world is going to have massive startup costs and there is plenty of resorces on Earth humanity is only tapping the tip of the iceburg so far .

Plus the first Antimatter factory be a high risk effort and it would be handy to put it far away from Earth in case of accidents.

Sending a ray down with the same intensity as sunlight, and which will defocus harmlessly if the pilot signal is interrupted, will have the environmentalists "up in arms", but shipping down packages of power which will explode like a nuke if containment fails, won't?


Who said anything about shipping anything to Earth there is massive markets in space already .Next gen power systems for next gen jobs .(Terraforming Mars and Venus )
You will not get much power with just sunlights intensity and weather happens plus any rectenna will be out in the boonies so power will decrease rapidy .Unless superconducters are avalible which opens other cheaper alternatives.
Title: Re: Solar Power Satellites
Post by: mheney on 06/30/2014 01:03 am
According to the web site at http://www.daviddarling.info/encyclopedia/A/antimatterprop.html, current annual antimatter production at CERN and Fermilab (combined) is between 1- 10 nanograms/year.  Hardly an industrial process, and we don't have any facilities the size of CERN in orbit ....  Whereas microwave transmisson of power has been demonstrated many times already ...

And if you're talking about having massive markets in space, then there's your market for beamed power.  Point-to-point power transmission works very well in space.

Finally, if you want to talk environmentalist outrage (politely known as "regulatory issues"), then if you think microwaves is going to cause howling, just wait until you start talking antimatter in industrial quantities.   Because there's a bit of a difference in an accident with a microwave beam and an accident with antimatter.  I'll take the microwaves any day of the week, thank you very much.

Bottom line, dismissing a (technically) demonstrated technology because a speculative, non-existant technology would be superior is a non-starter.  See http://en.wikipedia.org/wiki/Unobtainium (http://en.wikipedia.org/wiki/Unobtainium)
Title: Re: Solar Power Satellites
Post by: su27k on 06/30/2014 03:11 am
Peak beam intensity for most proposals is kept below 300W/m2 (about 1/4 to 1/3 mid-day sun)

This may be a problem, think about it, if the power density is less than that of the sun, why not just use the sun light directly? Yes I know there're nights, weather issues with terrestrial solar power, but they seem to be much easier to solve than the problems facing SPS.
Title: Re: Solar Power Satellites
Post by: bubbagret on 06/30/2014 03:30 am
Peak beam intensity for most proposals is kept below 300W/m2 (about 1/4 to 1/3 mid-day sun)

This may be a problem, think about it, if the power density is less than that of the sun, why not just use the sun light directly? Yes I know there're nights, weather issues with terrestrial solar power, but they seem to be much easier to solve than the problems facing SPS.

Having the beam at 1 relatively narrow frequency band, even at a lower total areal power, would be considerably more efficient than trying to convert full spectrum sunlight in to usable power. Solar electric usually only converts very specific, narrow frequencies as does solar thermal. That would only be a small percentage of the total solar flux reaching the surface and then at conversion efficiencies that reduce that small percentage even further.
Title: Re: Solar Power Satellites
Post by: Vultur on 06/30/2014 04:07 am
Why does the beam intensity have to be so low? Couldn't you just not put the beams on airplane flight routes? Surely the occasional bird being cooked would be greatly outweighed by all the environmental damage from other forms of power that wouldn't be happening (I doubt it would even remotely be comparable to all the bird deaths from hitting skyscrapers and towers and things).
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/30/2014 08:04 am
Why does the beam intensity have to be so low? Couldn't you just not put the beams on airplane flight routes? Surely the occasional bird being cooked would be greatly outweighed by all the environmental damage from other forms of power that wouldn't be happening (I doubt it would even remotely be comparable to all the bird deaths from hitting skyscrapers and towers and things).

There are two reasons:

1) There is already a large misplaced public perception that this would be a microwave "death ray", more dangerous than antimatter  :o. At least we have science on our side, giving a fundamental reason why that won't be the case:-

2) That fundamental reason is the diffraction limit; to halve the beam spot at the rectenna (and quadruple its intensity at the centre) requires doubling the diameter of the solar power satellite (SPS). To get the spot size down to 1 metre (where it could REALLY cause some sci-fi damage!) would require the satellite diameter (at GEO) to increase to 3,000km across.

For a geostationary SPS, the overall costs optimise for a design approximately 1km across and for power levels of 1GW or more. The reason we don't have one yet is due to launch costs, which Skylon and/or SpaceX FHR could address.
Title: Re: Solar Power Satellites
Post by: Asteroza on 06/30/2014 08:59 am
All the more reason why laser SPS has it's ups and downs. Small sizes are easier to demo overall. Tight spot size is great for reducing receiver area, but then it functionally approaches weapons grade beam densities rather quickly. Though I like to roll out that most space things are weapons already (most if not all satellites potentially can become kinetic impactor weapons from orbit).

The old SPS studies chose microwave because laser wasn't ready, and they chose the density to appeal to the average man who subjectively didn't relish the idea of being microwaved from orbit. As mentioned above, the physics says it needs to be 1Km or more for the transmitting antenna, at around 1GW based on those constraints. That fundamentally makes GEO demos hard. The japanese intend to do a LEO microwave demo as a proof-of-concept though, which is easier due to the distances involved at the expense of antenna tracking.

I have a personal belief (not necessarily backed with facts mind you) that laser (either laser thermal or hybrid laser PV/thermal) would be a better choice for the receiver architecture considering the process heat applications and not just electrical use. That, and it would enable a favorite pet idea, laser assisted Skylons.
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/30/2014 09:46 am
All the more reason why laser SPS has it's ups and downs. Small sizes are easier to demo overall. Tight spot size is great for reducing receiver area, but then it functionally approaches weapons grade beam densities rather quickly. Though I like to roll out that most space things are weapons already (most if not all satellites potentially can become kinetic impactor weapons from orbit).

Very true!

Quote
The old SPS studies chose microwave because laser wasn't ready, and they chose the density to appeal to the average man who subjectively didn't relish the idea of being microwaved from orbit. As mentioned above, the physics says it needs to be 1Km or more for the transmitting antenna, at around 1GW based on those constraints. That fundamentally makes GEO demos hard. The japanese intend to do a LEO microwave demo as a proof-of-concept though, which is easier due to the distances involved at the expense of antenna tracking.

Microwaves between 1-10GHz were also chosen for their ability to pass through thick cloud and rain; the 5.8GHz ISM band is near optimal.

I have a concept for a 1 gigawatt SPS called HESPeruS - Highly Elliptical Solar Power Satellite - which traverses a Molniya orbit, a highly-elliptical orbit first used by the Russians. Like GEO, this is also a synchronous orbit, in-that the SPS loiters over the same two northern hemisphere locations alternately every 12 hours. There are several benefits:

* HESPeruS is of rigid construction, built from multiple hexagonal modules into an essentially flat structure capable of collecting sunlight and beaming to any latitude  above 45 degrees, without the complex rotating optics as needed for the 2nd Japanese option (and ALL GEO satellites).
* HESPeruS is complementary to GEO space solar power proposals, which suffer additional losses when beaming to high latitudes; 30% of Earth's ice-free land and a $7 trillion economy is located above 45 degrees latitude.
* It's 5.8GHz antenna is distributed over the full 4.4km diameter, with individual elements vacuum-spaced by <25mm, drawing power (10s of milliwatts) from local PV cells which point directly at the sun throughout the orbit - so negligible distribution losses.
* The large antenna to PV ratio means it can operate within the diffraction limit at one-tenth scale (100MW), meaning a pilot system can be launched at lower cost, and then expanded later (Molniya is a servicable orbit!).
* It costs less than half as much (principally propellant mass) to place a satellite on a Molniya orbit than it does to GEO.
* Just 3 HESPeruS satellites can supply 1GW continuous (24/365) power to two rectenna sites, such as the UK and Japan.

Quote
I have a personal belief (not necessarily backed with facts mind you) that laser (either laser thermal or hybrid laser PV/thermal) would be a better choice for the receiver architecture considering the process heat applications and not just electrical use. That, and it would enable a favorite pet idea, laser assisted Skylons.

That's Keith Henson's idea (he comments here) - hopefully his paper will be published around the same time as mine!

(Edited for typos)
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/30/2014 07:36 pm
Peak beam intensity for most proposals is kept below 300W/m2 (about 1/4 to 1/3 mid-day sun)

This may be a problem, think about it, if the power density is less than that of the sun, why not just use the sun light directly? Yes I know there're nights, weather issues with terrestrial solar power, but they seem to be much easier to solve than the problems facing SPS.

If you have access to a desert wasteland then why not use it? India announced "The World's Largest Solar Power Plant" at 4GW: http://www.scientificamerican.com/article/india-to-build-worlds-largest-solar-power-plant/

When you look deeper, that 4GW is actually "6.4 billion kilowatt-hours per year", in other words an average of 730MW. At a construction cost of $4.4 billion, that's $6B/GW (the build cost for a typical nuclear power station is $8B/GW) - and that doesn't include any provision for energy storage; a 17.5 million kilowatt-hour battery would probably cost many times the plant itself - and would supply an average of 730MW for...     one day.

I'm sure all these cost and storage issues can be resolved (and will be) over time.

The solar plant covers an area of 77 square kilometres - which arranged as a disc would be nearly 10km across, or nearly 5 times greater land area than a 4.5km diameter rectenna. The land under solar panels is shaded and unsuitable for farming. The land under the rectenna receives just 5% of the stray microwave beam (max 15W/m2 for 300W/m2 peak beam intensity), but more than 90% of the sunlight.

The mature launch price for a 1GW HESPeruS is $3.2B (for all costs recovered, according to REL data).

[EDIT: to be fair, you need 3 HESPeruS to supply 2GW total for 24/365 shared between UK & Japan, so that's $4.8B/GW]

Title: Re: Solar Power Satellites
Post by: gospacex on 06/30/2014 09:02 pm
The land under solar panels is shaded and unsuitable for farming.

There are forest plants which *require* shade to grow. Some of them have edible berries.
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/30/2014 09:50 pm
The land under solar panels is shaded and unsuitable for farming.

There are forest plants which *require* shade to grow. Some of them have edible berries.

Thanks for the info
Title: Re: Solar Power Satellites
Post by: bad_astra on 06/30/2014 10:14 pm
Why not just pump a fraction of the vast amount of money this project would cost into a commercial fusion reactor?

It was a nice idea in the 70's when shuttles were going to fly once a week, fusion was 50 years away, and O'neal needed  a reason to design his wondrous colonies. This idea makes little sense now.
Title: Re: Solar Power Satellites
Post by: dror on 06/30/2014 10:26 pm
85% efficient over what distance?
Good question!

That is the efficiency for converting the incident beam power falling within the confines of the rectenna.
...
84% of the beam power is confined within a circular region called the "Airy disk" (George Biddell Airy), which dictates the minimum size of the rectenna and transmit antenna for a given frequency and beam path length.
...
Other losses are at the satellite-end of the beam and include:

PV efficiency - 40% expected from multi-junction concentrated cells (44.7% demonstrated)
                    -  20% --> >50% expected from future thin-film (e.g. perovskite research, 19% demonstrated)
                    -  bear in-mind that earth-orbit solar flux is 57% greater ...
...
                     - overall conversion efficiency (electrical --> microwave) could achieve >70%

So we add to that 2.5 longer time (24 hours instead of ~10) and we get:

Solar satelite energy = solar power plant energy × 0.85 × 0.84 × 0.7 × 1.57 × 2.5 = ~1.96×solar_power_plant_energy

So the satelite produces about twice as much energy per unit area, but requiers launch, structure and transmiter/antena/rectena infrastructure and 4.5 km radius on the ground.
The land solar plant uses about 5 times more erea of some desert..
I seriously dought the economics for that to succeed.

On top of that, any beamed energy from GEO is aditional heat for earth and will increase global warming as a fact.
 
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/30/2014 10:33 pm
Why not just pump a fraction of the vast amount of money this project would cost into a commercial fusion reactor?

It was a nice idea in the 70's when shuttles were going to fly once a week, fusion was 50 years away, and O'neal needed  a reason to design his wondrous colonies. This idea makes little sense now.

I'm all for fusion, but the closest thing to a commercial reactor is ITER, predicted to produce 500MW of HEAT (zero electricity) at a development cost "expected to be in excess of €15 billion" (Wikipedia).

That's $20B, or $40B/GW, or $67B/GW if you assume 60% thermal-->electrical efficiency.

Meanwhile, we have access to a fully functioning fusion reactor just 150 million km away.

We KNOW how to beam microwaves from space; we do it all the time from comms sats and GPS, it's a matter of scaling up and lowering launch costs.
Title: Re: Solar Power Satellites
Post by: QuantumG on 06/30/2014 10:34 pm
It was a nice idea in the 70's when shuttles were going to fly once a week, fusion was 50 years away, and O'neal needed  a reason to design his wondrous colonies. This idea makes little sense now.

Fusion is still 50 years away, reusable rockets are almost here (well, first stage reuse anyway, if SpaceX can actually launch again), the good professor's name was O'Neill, his colonies are still a good idea, and space solar power does indeed make more sense if you're looking at it from the perspective of people in space trying to produce something to trade with people on Earth.
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/30/2014 10:55 pm
So we add to that 2.5 longer time (24 hours instead of ~10) and we get:

Solar satelite energy = solar power plant energy × 0.85 × 0.84 × 0.7 × 1.57 × 2.5 = ~1.96×solar_power_plant_energy

So the satelite produces about twice as much energy per unit area, but requiers launch, structure and transmiter/antena/rectena infrastructure and 4.5 km radius on the ground.
The land solar plant uses about 5 times more erea of some desert..
I seriously dought the economics for that to succeed.

As I said, if you have access to a handy desert, use it - just use it more effectively than India or Ivanpah (Ivanpah... ask me, please  :D).

http://www.contemporaryenergy.co.uk/picts/solarm1.gif

The UK averages about 2.5kWh/m2 insolation per day, or 104W/m2. In-space average is 1367W

I make that 13 times better, not "twice as much"

Quote
On top of that, any beamed energy from GEO is aditional heat for earth and will increase global warming as a fact.

An 85% efficient rectenna reflects about 5% beam power back into space, so 10% is direct waste heat.
For 1GW to the grid, that's <120MW into the environment.

The best gas power stations have about 60% thermal efficiency, i.e. 40% direct waste heat into the environment.

For 1GW to the grid, that's 667MW into the environment.

Replacing 1GW of gas-fired power with equivalent SBSP reduces Earth's heat load by 547MW (fact).

In practice, the waste heat is negligible compared with the Earth's total insolation and the effect of C02.
Title: Re: Solar Power Satellites
Post by: Asteroza on 06/30/2014 11:52 pm
All the more reason why laser SPS has it's ups and downs. Small sizes are easier to demo overall. Tight spot size is great for reducing receiver area, but then it functionally approaches weapons grade beam densities rather quickly. Though I like to roll out that most space things are weapons already (most if not all satellites potentially can become kinetic impactor weapons from orbit).

Very true!

Quote
The old SPS studies chose microwave because laser wasn't ready, and they chose the density to appeal to the average man who subjectively didn't relish the idea of being microwaved from orbit. As mentioned above, the physics says it needs to be 1Km or more for the transmitting antenna, at around 1GW based on those constraints. That fundamentally makes GEO demos hard. The japanese intend to do a LEO microwave demo as a proof-of-concept though, which is easier due to the distances involved at the expense of antenna tracking.

Microwaves between 1-10GHz were also chosen for their ability to pass through thick cloud and rain; the 5.8GHz ISM band is near optimal.

I have a concept for a 1 gigawatt SPS called HESPeruS - Highly Elliptical Solar Power Satellite - which traverses a Molniya orbit, a highly-elliptical orbit first used by the Russians. Like GEO, this is also a synchronous orbit, in-that the SPS loiters over the same two northern hemisphere locations alternately every 12 hours. There are several benefits:

* HESPeruS is of rigid construction, built from multiple hexagonal modules into an essentially flat structure capable of collecting sunlight and beaming to any latitude  above 45 degrees, without the complex rotating optics as needed for the 2nd Japanese option (and ALL GEO satellites).
* HESPeruS is complementary to GEO space solar power proposals, which suffer additional losses when beaming to high latitudes; 30% of Earth's ice-free land and a $7 trillion economy is located above 45 degrees latitude.
* It's 5.8GHz antenna is distributed over the full 4.4km diameter, with individual elements vacuum-spaced by <25mm, drawing power (10s of milliwatts) from local PV cells which point directly at the sun throughout the orbit - so negligible distribution losses.
* The large antenna to PV ratio means it can operate within the diffraction limit at one-tenth scale (100MW), meaning a pilot system can be launched at lower cost, and then expanded later (Molniya is a servicable orbit!).
* It costs less than half as much (principally propellant mass) to place a satellite on a Molniya orbit than it does to GEO.
* Just 3 HESPeruS satellites can supply 1GW continuous (24/365) power to two rectenna sites, such as the UK and Japan.

Quote
I have a personal belief (not necessarily backed with facts mind you) that laser (either laser thermal or hybrid laser PV/thermal) would be a better choice for the receiver architecture considering the process heat applications and not just electrical use. That, and it would enable a favorite pet idea, laser assisted Skylons.

That's Keith Henson's idea (he comments here) - hopefully his paper will be published around the same time as mine!

(Edited for typos)

How does HESPeruS handle local sunrise/sunset orientation with respect to downlink antenna tracking? You appear to describe a single flat panel, but at local sunrise it will be edge-on with respect to the ground so the phased array aspect of the distributed aperture won't do you any favors there.
Title: Re: Solar Power Satellites
Post by: su27k on 07/01/2014 04:14 am
The mature launch price for a 1GW HESPeruS is $3.2B (for all costs recovered, according to REL data).

[EDIT: to be fair, you need 3 HESPeruS to supply 2GW total for 24/365 shared between UK & Japan, so that's $4.8B/GW]

Thanks for the numbers, they're interesting to look at. For the launch price, I assume this is using Skylon? Also what about the cost of the satellite themselves and the receivers? Japanese's plan seems to have an artificial island as receiver, that can't be cheap.
Title: Re: Solar Power Satellites
Post by: dror on 07/01/2014 07:10 am
So we add to that 2.5 longer time (24 hours instead of ~10) and we get:

Solar satelite energy = solar power plant energy × 0.85 × 0.84 × 0.7 × 1.57 × 2.5 = ~1.96×solar_power_plant_energy

So the satelite produces about twice as much energy per unit area, but requiers launch, structure and transmiter/antena/rectena infrastructure and 4.5 km radius on the ground.
The land solar plant uses about 5 times more erea of some desert..
I seriously dought the economics for that to succeed.

As I said, if you have access to a handy desert, use it - just use it more effectively than India or Ivanpah (Ivanpah... ask me, please  :D).

http://www.contemporaryenergy.co.uk/picts/solarm1.gif

The UK averages about 2.5kWh/m2 insolation per day, or 104W/m2. In-space average is 1367W

I make that 13 times better, not "twice as much"
But satelites has about 50% convertion panelty (0.84×0.85×0.7) that ground based facility dont have so it is about 7.5 times better for England and "about twice as much" for low altitude ereas.
Quote
Quote
On top of that, any beamed energy from GEO is aditional heat for earth and will increase global warming as a fact.

An 85% efficient rectenna reflects about 5% beam power back into space, so 10% is direct waste heat.
For 1GW to the grid, that's <120MW into the environment.

The best gas power stations have about 60% thermal efficiency, i.e. 40% direct waste heat into the environment.

For 1GW to the grid, that's 667MW into the environment.

Replacing 1GW of gas-fired power with equivalent SBSP reduces Earth's heat load by 547MW (fact).

In practice, the waste heat is negligible compared with the Earth's total insolation and the effect of C02.
All of the energy ends up as heat either way. 1 GW heat of microwave beam equals 1 GW heat of burnt coal or degraded plutonium.
When comparing to another non sustainable alternative, of course both are as bad.
I compared it to solar energy which uses the heat flux that is already coming to earth so it does not add to global warming (disregarding albedo difrences caused by the ground based panels) to show that space based solar energy cant be counted as sustainable, in opose to the general opinion.
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/01/2014 07:58 am
How does HESPeruS handle local sunrise/sunset orientation with respect to downlink antenna tracking? You appear to describe a single flat panel, but at local sunrise it will be edge-on with respect to the ground so the phased array aspect of the distributed aperture won't do you any favors there.

HESPeruS modules comprise a 3:1 stepped planar array, with fully integrated elements (PV + PMAD + Tx) at the half-wavelength scale (~25mm). The PV is at 90 degrees to the nominal boresight ( = rotation axis, normal to ecliptic), with the whole SPS rotating once-per-year to maintain PV directly sun-facing. The diagram shows the polar plot and local radiation pattern modelled for 22 elements.

HESPeruS travels along a highly elliptical Molniya orbit, loitering at northern apogee (40,000km) with a high-speed pass of the southern hemisphere at 450km perigee ("Molniya" == "Lightning", IIRC for its speed). I've defined "sunrise" as an SPS elevation of 20 degrees seen at the rectenna (northern latitudes above 45 degrees), which is sized accordingly (12km diameter).

Typical beam times are 9 hours 29 minutes for each 11 hour 58 minute orbit, satisfying elevation (>20 deg), beam sweep (+/- 50 deg) and diffraction limits (using effective apertures).
Title: Re: Solar Power Satellites
Post by: Alf Fass on 07/01/2014 08:07 am


As I said, if you have access to a handy desert, use it - just use it more effectively than India or Ivanpah (Ivanpah... ask me, please  :D).

http://www.contemporaryenergy.co.uk/picts/solarm1.gif

The UK averages about 2.5kWh/m2 insolation per day, or 104W/m2. In-space average is 1367W

I make that 13 times better, not "twice as much"


that 104W/m2 is for an unsteered surface flat to the ground.
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/01/2014 08:13 am
The UK averages about 2.5kWh/m2 insolation per day, or 104W/m2. In-space average is 1367W

I make that 13 times better, not "twice as much"
But satelites has about 50% convertion panelty (0.84×0.85×0.7) that ground based facility dont have so it is about 7.5 times better for England and "about twice as much" for low altitude ereas.
Quote
Quote
On top of that, any beamed energy from GEO is aditional heat for earth and will increase global warming as a fact.

An 85% efficient rectenna reflects about 5% beam power back into space, so 10% is direct waste heat.
For 1GW to the grid, that's <120MW into the environment.

The best gas power stations have about 60% thermal efficiency, i.e. 40% direct waste heat into the environment.

For 1GW to the grid, that's 667MW into the environment.

Replacing 1GW of gas-fired power with equivalent SBSP reduces Earth's heat load by 547MW (fact).

In practice, the waste heat is negligible compared with the Earth's total insolation and the effect of C02.
All of the energy ends up as heat either way. 1 GW heat of microwave beam equals 1 GW heat of burnt coal or degraded plutonium.
When comparing to another non sustainable alternative, of course both are as bad.
I compared it to solar energy which uses the heat flux that is already coming to earth so it does not add to global warming (disregarding albedo difrences caused by the ground based panels) to show that space based solar energy cant be counted as sustainable, in opose to the general opinion.
Yes, SBSP is typically 7.5 times better than non-tracking terrestrial PV (including all losses) for northern latitudes. How much benefit do you associate with predictable baseload power? How much cost do you associate with storage to overcome intermittency?

The best terrestrial PV (concentrated) is still about 40% efficient, with low albedo, so 40%-60% waste heat rejected to the environment. I'm happy to disregard albedo; all rejected and useful power ends up as heat - it's still negligible compared with solar influx and heat trapping due to C02.
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/01/2014 08:27 am
The mature launch price for a 1GW HESPeruS is $3.2B (for all costs recovered, according to REL data).

[EDIT: to be fair, you need 3 HESPeruS to supply 2GW total for 24/365 shared between UK & Japan, so that's $4.8B/GW]

Thanks for the numbers, they're interesting to look at. For the launch price, I assume this is using Skylon? Also what about the cost of the satellite themselves and the receivers? Japanese's plan seems to have an artificial island as receiver, that can't be cheap.

Yes, launch price is based on mature Skylon operations, including servicing missions for Fluyt. Data was kindly supplied by REL specifically for launching 10 tonnes payload (HESPeruS + Fluyt propellant) to 300km orbit at 63.4deg inclination, with construction via Fluyt carrying 49 tonnes of HESPeruS to Molniya before returning to 300km.

From memory, JAXA was assuming much higher beam intensity - which would have to be away from population centres.

I've focussed on launch price, which has traditionally been the dominant factor. I don't yet have useful materials costs, which will depend on mass production.

Fortunately, wireless comms (incl 5.8GHz WiFi) and terrestrial solar are both driving research and mass production in the right direction.
Title: Re: Solar Power Satellites
Post by: Asteroza on 07/01/2014 08:59 am
Japanese construction companies (the big general contractors) are addicted to large civil works projects like a crack fiend. That, and the general japanese government view that large civil works projects are the preferred form of economic stimulus (via construction worker salary trickle down economics effects).

That said, rather than a true artificial island, they may go for a megafloat modular concrete barge island. There's currently on the table a potential project for a large offshore megafloat based heliport structure to service offshore oil/gas rigs which are too far to service by conventional helicopter easily from japan. Though at the scales involved, a PSP type module for the megafloat rather than a conventional rectangular barge may be a better option.
Title: Re: Solar Power Satellites
Post by: Asteroza on 07/01/2014 09:16 am
How does HESPeruS handle local sunrise/sunset orientation with respect to downlink antenna tracking? You appear to describe a single flat panel, but at local sunrise it will be edge-on with respect to the ground so the phased array aspect of the distributed aperture won't do you any favors there.

HESPeruS modules comprise a 3:1 stepped planar array, with fully integrated elements (PV + PMAD + Tx) at the half-wavelength scale (~25mm). The PV is at 90 degrees to the nominal boresight ( = rotation axis, normal to ecliptic), with the whole SPS rotating once-per-year to maintain PV directly sun-facing. The diagram shows the polar plot and local radiation pattern modelled for 22 elements.

HESPeruS travels along a highly elliptical Molniya orbit, loitering at northern apogee (40,000km) with a high-speed pass of the southern hemisphere at 450km perigee ("Molniya" == "Lightning", IIRC for its speed). I've defined "sunrise" as an SPS elevation of 20 degrees seen at the rectenna (northern latitudes above 45 degrees), which is sized accordingly (12km diameter).

Typical beam times are 9 hours 29 minutes for each 11 hour 58 minute orbit, satisfying elevation (>20 deg), beam sweep (+/- 50 deg) and diffraction limits (using effective apertures).

Maybe I'm not understanding correctly, but what happens when the SPS lines up with the day/night terminator line while near the top of the Molniya loiter then, unless you phase orbits to avoid that scenario?
Title: Re: Solar Power Satellites
Post by: gospacex on 07/01/2014 10:16 am
The best terrestrial PV (concentrated) is still about 40% efficient, with low albedo, so 40%-60% waste heat rejected to the environment. I'm happy to disregard albedo; all rejected and useful power ends up as heat - it's still negligible compared with solar influx and heat trapping due to C02.

You didn't understand the argument. With terrestrial solar panels, you capture as useful energy some energy which *would otherwise end up absorbed by Earth anyway*. With SBSP, the energy you capture and send to Earth *would otherwise fly past the planet*.
Title: Re: Solar Power Satellites
Post by: Alf Fass on 07/01/2014 10:21 am
The best terrestrial PV (concentrated) is still about 40% efficient, with low albedo, so 40%-60% waste heat rejected to the environment. I'm happy to disregard albedo; all rejected and useful power ends up as heat - it's still negligible compared with solar influx and heat trapping due to C02.

You didn't understand the argument. With terrestrial solar panels, you capture as useful energy some energy which *would otherwise end up absorbed by Earth anyway*. With SBSP, the energy you capture and send to Earth *would otherwise fly past the planet*.

A pointless argument, whether space or surface based the difference it makes to the amount of energy the Earth receives is truly negligible.
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/01/2014 10:33 am
Maybe I'm not understanding correctly, but what happens when the SPS lines up with the day/night terminator line while near the top of the Molniya loiter then, unless you phase orbits to avoid that scenario?

HESPeruS is never in Earth's shadow when other beam constraints are met. A Molniya orbit is inclined at 63.4deg taking it WAY above the northern hemisphere. The diagram is not to scale (obviously), but the solar angle (shown from Earth's tilted perspective) and orbit proportions are correct. The "SPS" represents a small section of one module - the tiered arrangement is at ~25mm scale.

Were you considering something similar to 70 minute GEO outtages during Spring/Vernal equinoxes?
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/01/2014 10:42 am
You didn't understand the argument. With terrestrial solar panels, you capture as useful energy some energy which *would otherwise end up absorbed by Earth anyway*. With SBSP, the energy you capture and send to Earth *would otherwise fly past the planet*.

It does not matter whether you include terrestrial PV albedo (making light reflective sandy deserts much darker) or not:

It is still insignificant compared with total solar influx and GHG heat trapping.
Title: Re: Solar Power Satellites
Post by: gospacex on 07/01/2014 10:45 am
You didn't understand the argument. With terrestrial solar panels, you capture as useful energy some energy which *would otherwise end up absorbed by Earth anyway*. With SBSP, the energy you capture and send to Earth *would otherwise fly past the planet*.

It does not matter whether you include terrestrial PV albedo (making light reflective sandy deserts much darker) or not:

It is still insignificant compared with total solar influx and GHG heat trapping.

I didn't say it matters. I said that your argument "but terrestrial solar PV also dissipates waste heat" is wrong, because that solar energy would arrive and be dissipated in this location *anyway*.
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/01/2014 10:51 am
I didn't say it matters. I said that your argument "but terrestrial solar PV also dissipates waste heat" is wrong, because that solar energy would arrive and be dissipated in this location *anyway*.

I'm glad we agree it doesn't matter.
Title: Re: Solar Power Satellites
Post by: dror on 07/01/2014 12:56 pm
I didn't say it matters. I said that your argument "but terrestrial solar PV also dissipates waste heat" is wrong, because that solar energy would arrive and be dissipated in this location *anyway*.

I'm glad we agree it doesn't matter.
It may not matter for one satelite.
How many satelites can you build befor it starts to matter?
50 GW?
500 GW?
5 TW?

Btw, tracking modules which combine concentrated thermal electric and pv can get 60 - 80% efficient.
Title: Re: Solar Power Satellites
Post by: JasonAW3 on 07/01/2014 01:20 pm
Ok guys,

     This may seem like a dumb idea, but, instead of spending hundreds of billions of dollars to build a solar array in space, why not send up an inflatable array using thin film solar panels to convert sunlight to electricity, an inflatable directional microwave antenna on the back to transmit the energy back down to Earth and strategically placed solar electric thrusters to maintain attitude as needed.

     Using a thin mylar film as the inflatable structure, you should be able to get at least 1 kilometer of solar array per ton of mass.  Assuming the microwave antenna and gear plus the solar electric thrusters mss about 10 tons, bosting a 30 ton mass into Geosynch orbit should give us a 20 kilometer array that should be able generate at least 215 Gigawatts.

     There are a number of launchers that should be able to boost it into orbit and more than enough upper stages that can boost 30tons to Geosynch orbit.
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/01/2014 01:21 pm
I didn't say it matters. I said that your argument "but terrestrial solar PV also dissipates waste heat" is wrong, because that solar energy would arrive and be dissipated in this location *anyway*.

I'm glad we agree it doesn't matter.
It may not matter for one satelite.
How many satelites can you build befor it starts to matter?
50 GW?
500 GW?
5 TW?

World consumption in 2008 was about 16.4TW, it would need to grow by 8-10,000 times to reach parity with total insolation:
http://en.wikipedia.org/wiki/Solar_energy
http://en.wikipedia.org/wiki/World_energy_consumption

Quote
Btw, tracking modules which combine concentrated thermal electric and pv can get 60 - 80% efficient.

Ivanpah manages 2.7% peak efficiency at $19.6B/GW build cost.
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/01/2014 01:24 pm
...why not send up an inflatable array...

http://www.stratosolar.com/
Title: Re: Solar Power Satellites
Post by: Asteroza on 07/02/2014 12:33 am
Maybe I'm not understanding correctly, but what happens when the SPS lines up with the day/night terminator line while near the top of the Molniya loiter then, unless you phase orbits to avoid that scenario?

HESPeruS is never in Earth's shadow when other beam constraints are met. A Molniya orbit is inclined at 63.4deg taking it WAY above the northern hemisphere. The diagram is not to scale (obviously), but the solar angle (shown from Earth's tilted perspective) and orbit proportions are correct. The "SPS" represents a small section of one module - the tiered arrangement is at ~25mm scale.

Were you considering something similar to 70 minute GEO outtages during Spring/Vernal equinoxes?

No no, it wasn't equinox outages. I had pictured HESPeruS to be a single contiguous flat panel, along the lines of currently proposed sandwich panels for SPS, thus only showing one large contiguous planar area (where the emitters would be mounted across the entire area of the panel) and one nadir edge to earth. Thus, if edge on to earth or close, you go beyond the reasonable beam steering limits of a phased array. The stepped venetian blind structure you show where the emitters line the long linear strip panel edges neatly sidesteps that problem. Are the steps a fully fixed structure then? Though that makes for interesting orientation issues, likely compensated by smart precession and beam steering.


Bad thought of the day, the high speed pass portion is pretty low (as you say, 450 Km perigee).  Is there the possibility of using the beamed power of the SPS to power an LV upper stage or orbital tug during the high speed pass, as nominally the odds of a terrestrial power user being in the footprint of the high speed pass would be low? At such close range, the beam spot is much tighter and have utility in various ways. An inflated ring rectenna for an orbital tug could power electric propulsion systems, and Parkin's microwave thermal rocket work would be applicable (AKA microwave Skylon variant of Henson's laser Skylon, and the associated SPS bootstrapping)
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/02/2014 08:18 am
Asteroza,

HESPeruS has some commonality with sandwich panels including:
* modular construction
* short distance power distribution
* no single point power bottleneck, such as a rotating joint

As shown, the "venetian blind" sections combine into a hexagonal module <4.8m across vertices. Each module is actually a subtle 3D tetrahedron for rigidity, which is continued across multiple fractal scales (eliminating the requirement for additional truss sections or other support backbone). I have done some further work which solves high density stacking issues within the Skylon hold (must be limited by payload mass not volume!).

The diagram also shows the option for thin-film or concentrated PV at each element. Quad junction CPV has been demonstrated at 44.7% efficiency (40% assumed). Thin film PV (eg perovskite) offers lower mass, but cannot yet match efficiency (though huge gains have been made in a short period, from 3% to currently 19%).

I have discussed the possibility of boot-strapping construction (using one SPS to boost the components for another into Molniya via microwave thermal propulsion) with Keith Henson. However, he suggests the orbital phasing and beam times will not work in its favour.

[Edit]
Quote
Though that makes for interesting orientation issues, likely compensated by smart precession and beam steering.
The boresight beam axis is also the rotation axis, aligned normal to the ecliptic. The whole SPS rotates once per year to maintain PV (or concentrating fresnel reflectors) face-on to the sun. At perigee, the SPS will be travelling mostly edge-on to the residual atmosphere. Not quite GOCE streamlining, but better than the alternative if drag is to be minimised. OTOH, there is no junkyard orbit required for end-of-life modules; only a small nudge will ensure re-entry happens in a predictable timeframe.

Beam steering is retrodirective, based on synchronised sampling and time-reversal of the incoming 40.68MHz pilot beam wavefront (with minimally accurate targeting performed by the rectenna ground facility). The SPS requires no "knowledge" of where the rectenna actually is, but may need to perform small phase corrections (e.g. linear prediction) to allow for RF time-of-flight delays.

Title: Re: Solar Power Satellites
Post by: Hanelyp on 07/02/2014 07:51 pm
How does HESPeruS keep modules on opposite sides of the array in phase for beam forming?
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/02/2014 09:53 pm
How does HESPeruS keep modules on opposite sides of the array in phase for beam forming?
The key is synchronisation, both inter-module and intra-module (between all 25 billion elements). Its covered over several pages, but I'll try and summarise:

* Distribute a synchronised timing reference across the whole system, linked to the Pilot Beam frequency (40.68MHz)
* Perform synchronised sampling of the Pilot Beam wave-front at several points across each module to determine phase values (three points on a plane).
* Use time-of-flight knowledge and recent phase history to predict small phase corrections for RF round-trip delay.
* Distribute two time-reversed phase values (and the timing reference) to each element in a linear string.
* At each element, synchronise a 1:143 PLL to the position-weighted average of the two phases to generate a local 5.8GHz power beam.

Inter-module uses 100GHz duplex fibre (as for standard Ethernet) at the six module sides - there are no electrical connections between modules. One module is designated as "Master" (could be any; not position dependent).

A unique duplex path is determined between all functioning modules (routes around any failures). The Master sends out a regular timing burst passed module-module until it reaches the End Node, where it is reflected back along the same duplex path to the Master - averages about 62ms for the million modules.

At any module, the timing reference is defined as the average of the outbound and return bursts. The outbound and return paths are regularly swapped to eliminate path length errors.

The same thing happens intra-module, but at 40.68MHz and broadcast (not element-to-element).



Title: Re: Solar Power Satellites
Post by: Asteroza on 07/02/2014 11:36 pm

I have discussed the possibility of boot-strapping construction (using one SPS to boost the components for another into Molniya via microwave thermal propulsion) with Keith Henson. However, he suggests the orbital phasing and beam times will not work in its favour.


That's a little unexpected, but possible. Skylon dumping direct to a Molniya inclination but a sub-450 km circular parking orbit seemed to be a good choice at first. After that trade against full construction then apogee raising of a completed SPS or apogee raise all parts module by module before joining. Single module apogee raising using something like a microwave powered Flyut while the bootstrap SPS sweeps towards perigee seems doable even if microwave Skylon itself is unattractive due to launch site distance from perigee ground track specific to the Molniya orbit you wish to service.
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/03/2014 05:46 am

I have discussed the possibility of boot-strapping construction (using one SPS to boost the components for another into Molniya via microwave thermal propulsion) with Keith Henson. However, he suggests the orbital phasing and beam times will not work in its favour.

That's a little unexpected, but possible. Skylon dumping direct to a Molniya inclination but a sub-450 km circular parking orbit seemed to be a good choice at first. After that trade against full construction then apogee raising of a completed SPS or apogee raise all parts module by module before joining. Single module apogee raising using something like a microwave powered Flyut while the bootstrap SPS sweeps towards perigee seems doable even if microwave Skylon itself is unattractive due to launch site distance from perigee ground track specific to the Molniya orbit you wish to service.

I haven't tried to model this; Keith has for laser-thermal GTO, but I'd presume not for Molniya. Would anyone here like to have a go?

The diffraction limit at 5.8GHz, from a 4.4km diameter antenna down to a 1 metre spot, gives <35km beam distance, which is one reason for pessimism.

[Edit]
Could make a good anti-missile defence for the SPS though; provided the missiles abide by the rules and don't try to attack the non-beaming side!  :)

[Edit2]
...and the missiles agree to play fair and send out a 40.68MHz homing signal  :) :)

Title: Re: Solar Power Satellites
Post by: Hanelyp on 07/03/2014 05:15 pm
[Edit2]
...and the missiles agree to play fair and send out a 40.68MHz homing signal  :) :)
If you were serious about anti-missile capability on the solar array, a less directional system could illuminate a target missile with the homing signal.  Though with a 40MHz homing signal the warhead bus might be made too small to reflect the signal well.
Title: Re: Solar Power Satellites
Post by: Asteroza on 07/04/2014 12:11 am

I have discussed the possibility of boot-strapping construction (using one SPS to boost the components for another into Molniya via microwave thermal propulsion) with Keith Henson. However, he suggests the orbital phasing and beam times will not work in its favour.

That's a little unexpected, but possible. Skylon dumping direct to a Molniya inclination but a sub-450 km circular parking orbit seemed to be a good choice at first. After that trade against full construction then apogee raising of a completed SPS or apogee raise all parts module by module before joining. Single module apogee raising using something like a microwave powered Flyut while the bootstrap SPS sweeps towards perigee seems doable even if microwave Skylon itself is unattractive due to launch site distance from perigee ground track specific to the Molniya orbit you wish to service.

I haven't tried to model this; Keith has for laser-thermal GTO, but I'd presume not for Molniya. Would anyone here like to have a go?

The diffraction limit at 5.8GHz, from a 4.4km diameter antenna down to a 1 metre spot, gives <35km beam distance, which is one reason for pessimism.

[Edit]
Could make a good anti-missile defence for the SPS though; provided the missiles abide by the rules and don't try to attack the non-beaming side!  :)

[Edit2]
...and the missiles agree to play fair and send out a 40.68MHz homing signal  :) :)

Fore reference, what are the distances for 2,3,4,5, and 10m spots? I suspect even then the distances would be unattractive for a Skylon but potentially usable for a orbital tug which can open up a large rectenna via an inflatable ring with 10m not being unreasonable.

It's probably unrealistic to do the external heating for a Skylon via microwave if you have to do the heating as two smaller spots on the wing upper surface of the current Sklyon configuration. Which is why I always imagined externally heated Skylon to be a flipped configuration, with the wing on the top of the fuselage and the payload bay opening towards the bottom. This allows a much larger single receiver surface which can double as thermal protection for reentry, provided you did reentry upside-down. That 180 roll before and after reentry is the obnoxious part (since a passenger module will need seats that rotate 180), but it keeps the hot side uninterrupted with landing gear doors. 180 degree roll is potentially a deal-breaker, but then again, many nose first reentry VTVL SSTO designs had "swoop-of-death" maneuver that people felt was acceptable.

Perhaps a different bootstrap concept might be in order. If one could accept the bootstrap/demo sat can't be reasonably used for continuous utility power service, a low SSO SPS riding the day/night terminator to supply dedicated propulsion power might be possible. How that propulsion power is beamed (Henson uses laser, but microwave might work here) determines the utility of it. Oddly enough, that would force you to do predawn and post-dusk Skylon flights or tug boosts.
Title: Re: Solar Power Satellites
Post by: SICA Design on 07/04/2014 07:47 am
The diffraction limit is approximated by the inequality:

(A x D) / (λ x R) > 2.44

where A is antenna aperture (diameter), D is rectenna diameter, λ is the wavelength (51.7mm for 5.8GHz) and R is the beam distance. So the maximum beam length will change in proportion to the spot size if everything else stays constant.

I like the idea of a Skylon without breaks in the TPS for wheel wells, but as recently commented on 'Skylon Thread 4', it's not designed for combat manouvres - which I guess includes barrel rolls!
Title: Re: Solar Power Satellites
Post by: SICA Design on 10/15/2014 08:25 pm
Article on HESPeruS published in the IET's magazine recently:

http://eandt.theiet.org/magazine/2014/10/space-based-solar-power.cfm

Title: Re: Solar Power Satellites
Post by: Robotbeat on 10/15/2014 11:43 pm
Should use lasers and find a customer that needs a lot of power and is willing to pay a LOT more than $0.10/kWh and lives above the clouds and could use a system at the hundreds of kW range to start.
Title: Re: Solar Power Satellites
Post by: QuantumG on 10/16/2014 12:51 am
Should use lasers and find a customer that needs a lot of power and is willing to pay a LOT more than $0.10/kWh and lives above the clouds and could use a system at the hundreds of kW range to start.

Cloud servers in the clouds.

Title: Re: Solar Power Satellites
Post by: Vultur on 10/17/2014 06:26 am
How much would a HESPeruS satellite cost? (not including launch costs as obviously that's highly dependent on how cheap Skylon and/or SpaceX reusability turn out to be in actual practice...)
Title: Re: Solar Power Satellites
Post by: MP99 on 10/17/2014 07:59 am


Should use lasers and find a customer that needs a lot of power and is willing to pay a LOT more than $0.10/kWh and lives above the clouds and could use a system at the hundreds of kW range to start.

Cloud servers in the clouds.

Dunno, that perigee sounds a bit low. ;-)

Cheers, Martin
Title: Re: Solar Power Satellites
Post by: Asteroza on 10/17/2014 08:15 am
Should use lasers and find a customer that needs a lot of power and is willing to pay a LOT more than $0.10/kWh and lives above the clouds and could use a system at the hundreds of kW range to start.

Cloud servers in the clouds.

Well, Facebook/Ascenta or Google/Titan Aerospace have solar electric HALE drone projects. Tuned solar cells for receiving laser light from above is not entirely crazy (see Lasermotive UAV demos). Good pointing accuracy isn't necessary if the spot is wide and at light sunburn levels of power...
Title: Re: Solar Power Satellites
Post by: SICA Design on 10/17/2014 08:48 am
How much would a HESPeruS satellite cost? (not including launch costs as obviously that's highly dependent on how cheap Skylon and/or SpaceX reusability turn out to be in actual practice...)
To estimate the future cost (1-2 decades hence) of materials and manufacture is incredibly difficult and prone to inaccuracy.

What I can state is that the HESPeruS design uses very few types of component:

Almost the entire functionality is modular down to a 25mm scale - including photovoltaics (either concentrated multi-junction, or future thin fim, e.g. perovskite), dc to microwave conversion at <100mW levels (single CMOS ASIC) and micro-wave beam formation (dual crossed dipole / crossed elliptical antenna).

Combining 25,000 of these elements into a modular panel (~5m across), including several pilot beam receivers, allows coherent microwave beam formation and retro-directive steering. Up to 1 million panels would be necessary for a complete system delivering 1GW to the grid.

Getting costs down to economical levels will require extreme mass-production and automation, the same drive which has put powerful processing and microwave technology into peoples pockets, to be discarded as throw-away items after one or two years.
Title: Re: Solar Power Satellites
Post by: SICA Design on 10/17/2014 08:55 am
Should use lasers and find a customer that needs a lot of power and is willing to pay a LOT more than $0.10/kWh and lives above the clouds and could use a system at the hundreds of kW range to start.

Cloud servers in the clouds.

Well, Facebook/Ascenta or Google/Titan Aerospace have solar electric HALE drone projects. Tuned solar cells for receiving laser light from above is not entirely crazy (see Lasermotive UAV demos). Good pointing accuracy isn't necessary if the spot is wide and at light sunburn levels of power...

John Mankins is promoting space-based servers as a good means to kick-start Space Based Solar Power

http://www.nss.org/adastra/volume25/spsalpha.html
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/07/2017 09:10 am
Including one notable and impending reversal, there are currently 191 signatories to the Paris Climate Agreement, all recognising the need to reduce man-made greenhouse gas emissions, due primarily to the combustion of fossil fuels. With widespread distrust and lack of nuclear power investment, there are few options which can replace the guaranteed baseload power provided by coal, oil and gas.

There is rapid and increasing uptake of both wind and solar power, but almost zero grid-scale storage necessary to overcome their unpredictable nature. In 2015, the three largest terrestrial solar photovoltaic farms provided (on-average) just 5 watts per square metre. This is similar for solar-thermal plants and less for wind-power.

To generate the 28 terrawatts predicted total world power requirement by 2050 (for a global population expected to peak below 10 billion), a massive increase in wind and solar will likely compete with food production for available land. However, there is a band located around the Earth from which we could extract all this power many-times over, beamed as biologically and ecologically benign microwaves, converted with over 90% efficiency to electricity (50% end-to-end efficiency), from which we can then meet all our energy needs.

We’ve known about this since the early 1970’s, and we have had daily demonstrations of the fundamental technology ever since the first geostationary communications satellite was placed in orbit. The only significant difference between a communications and a power satellite is the scale required to capture the majority of the beam.

From geosynchronous orbits, fundamental physics dictates a kilometre-scale transmit antenna to beam microwave power across 36,000 km of space, through the atmosphere during all weathers, to a multi-kilometre terrestrial receiving station (rectifying antenna or “rectenna”) – and do this without prohibitive losses. This is irrespective of how much power, so it better be in the region of gigawatts (GW) delivered, to justify the massive transmitter, which still leads to a peak beam intensity weaker than sunlight at the ground (so forget those “space-weapon” fears).

Nearly all proposals take a high-level systems approach, splitting the satellite into the antenna facing the Earth and the collector facing the Sun. This inevitably leads to a complex kilometre-scale 3D structure with continuously moving parts as the satellite traverses its orbit. In 1971, one proposed 5 GW solar power satellite (SPS) massed 34,000 tonnes, with typical concepts today still around 5,000-10,000 T/GW.

HESPeruS (JBIS, Vol. 69, pp 127-138, 2016 http://jbis.org.uk/paper.php?p=2016.69.127 ) is a proposal which eliminates the moving parts in-favour of a solid state design. Its essentially-flat and highly modular structure reduces mass to around one tenth that of competing designs, and simplifies robotic orbital construction - but that orbit needs to be a highly elliptical (Molniya) orbit in order to both face the Sun and stay within its beam steering limits.
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/07/2017 09:22 am
IN THE INTERESTS OF PUBLIC DISCLOSURE:

CASSIOPeiA – Constant Aperture, Solid State, Integrated, Orbital Phased Array


The recent invention of CASSIOPeiA (patent applied for), has realised a scalable design which can work in any orbit, capable of both directly facing the Sun and beaming continuously through 360 degrees, solving the beam steering issues of a planar array without any mass penalty.

CASSIOPeiA deploys from a highly compact stowed form, into a gossamer large-scale helical array, having sufficient self-rigidity to support itself in microgravity. Unlike a parabolic dish (for example), there is no need to maintain a perfect rigid geometry in the presence of varying thermal expansion, nor precision pointing accuracy. Instead, the power beam is formed and locked on target by measuring the spherical wavefront of a pilot signal emitted by the terrestrial station, synchronously sampled by numerous receivers across the orbital array, with phase measurements reversed in time to generate the coherent power beam.

Key to the design are the half-wavelength spaced elements, which combine highly efficient concentrated photovoltaics with a triple antenna configuration - able to electronically steer a shaped radiation pattern (cardioid) through 360 degrees. This combination of steerable element pattern and the constant aperture (cross-sectional area as seen from the Earth) of a helical surface results in a high quality beam, matching that of an equivalent planar array’s ideal boresight direction, but invariant throughout 360 degrees azimuth, combined with +/-55 degrees elevation (elevation limits where peak intensity drops by 3dB, “azimuth” and “elevation” with respect to the rotational axis of the array).

This integration allows the flexible substrate to provide mechanical support, electrical interconnect and simplified thermal management – functions typically assigned to distinct large-scale structures in other SPS proposals.

By matching CASSIOPeiA’s RF aperture to the area of intercepted sunlight, the design is completely scalable from 200 kW to 600 MW predictable delivered power. Examples:

1)   A pseudo-satellite measuring 34m across, massing 200-400kg and situated at 20 km altitude inside the transparent envelope of a station-keeping stratospheric blimp (see Thales Stratobus for a near-term example), providing 200 kW continuous power throughout daylight hours.
2)   A constellation of 300m diameter, 20-40 tonne satellites following offset Sun-synchronous 2-hour orbits, skipping over Earth’s shadow to provide near-continuous power at 20 MW. Each satellite conceivably launched and deployed as a single payload.
3)   Similar 400m diameter, 33-66 T satellites delivering 33 MW from 2-hour 24-minute Sun-synchronous orbits.
4)   A constellation of 5 satellites, each 650 m diameter, massing 90-180 T, delivering 90 MW to multiple northern latitude sites from 3-hour, Sun-synchronous elliptical orbits. Rectenna utilisation is > 95% at 45 degrees latitude, >98.5% at 60 degrees (see figure).
5)   A single 1.4 km diameter geosynchronous satellite, massing 430 - 860 T 600 – 1200 T, delivering 430 600 MW with >99% utilisation.

All these examples provide surface beam intensities no-greater than one-quarter sunlight, intrinsically safe to wildlife, with average delivered surface power densities ten times greater than the current best wind and terrestrial solar sites. The option to safely and aesthetically combine rectenna sites with agriculture (by raising the mesh-like rectenna several metres above the ground) removes the potential future conflict between food and power production.

[Edit: correction to GSO example 5, for delivered power, not total RF power]
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 06/07/2017 06:05 pm
Unfortunately all current solar installations can't provided base load.
For SPS to every be viable they need to be built in space from space materials eg moon or asteriods. The technology to do this is evolving but we have long way to go.
The other critical item is pilot satellite to prove beaming high quatities of power back is possible.

Sent from my SM-G570Y using Tapatalk

Title: Re: Solar Power Satellites
Post by: Robotbeat on 06/07/2017 06:21 pm
Unfortunately all current solar installations can't provided base load.
For SPS to every be viable they need to be built in space from space materials eg moon or asteriods. The technology to do this is evolving but we have long way to go.
The other critical item is pilot satellite to prove beaming high quatities of power back is possible.

Sent from my SM-G570Y using Tapatalk
Oft-repeated myth. Terrestrial photovoltaics can provide baseload if oversized (to provide power during cloudy days) or geographically diversified and coupled with batteries.

Additionally, I don't think building SBSP with space resources is required (or even competitive) if you get launch costs low enough.
Title: Re: Solar Power Satellites
Post by: Asteroza on 06/07/2017 11:27 pm
IN THE INTERESTS OF PUBLIC DISCLOSURE:

CASSIOPeiA – Constant Aperture, Solid State, Integrated, Orbital Phased Array



I think I get the design, but is the helix central axis actively pointed at the sun, or are you willing to take the off-angle power efficiency loss to utilize passive pointing? Like Mankin's SPS-ALPHA, unless you have a lot of good orientation/beaming pictures, people will have trouble visualizing the arrangement and usage. If passive, would you also be using an upward tether mass to gravity gradient stabilize the nadir pointing of the phased array, or will you also be using active means to roll the helix to improve pointing at specific ground targets?

The physical arrangement is unique and very interesting as a solution to the power slip ring bearing issue that plagues classic SPS designs. Recent designs like the NASA butterfly tend to end up with a GEO fixed sandwich panel design of sorts, though SPS-ALPHA does the psuedo-cone arrangement, and the recent FISO presentation on Z step sandwich panel module research had a rather interesting central stepped cone arrangement replacing the traditional fixed flat disk of the NASA butterfly design (which is conceptually similar to this helix arrangement even if visually not so). Nice to see more people thinking beyond rectilinear 3D.

I guess you could also call it a heliogyro style of sorts...

But how does the GEO case work without relay mirrors like the NASA butterfly design, for a single satellite design? Wouldn't a 24 hour sun tracking spin to keep the PV panels lit also point the phased array primary axis so far off orthogonally that you would get terrible transmission efficiency?
Title: Re: Solar Power Satellites
Post by: QuantumG on 06/08/2017 01:08 am
I really don't care if terrestrial solar is better than solar power satellites.

Can we talk about the topic please?

34,000 tons sounds like fun. 100 ITS flights or 200 mini-ITS?



Title: Re: Solar Power Satellites
Post by: TrevorMonty on 06/08/2017 03:23 am
IN THE INTERESTS OF PUBLIC DISCLOSURE:

CASSIOPeiA – Constant Aperture, Solid State, Integrated, Orbital Phased Array



I think I get the design, but is the helix central axis actively pointed at the sun, or are you willing to take the off-angle power efficiency loss to utilize passive pointing? Like Mankin's SPS-ALPHA, unless you have a lot of good orientation/beaming pictures, people will have trouble visualizing the arrangement and usage. If passive, would you also be using an upward tether mass to gravity gradient stabilize the nadir pointing of the phased array, or will you also be using active means to roll the helix to improve pointing at specific ground targets?

The physical arrangement is unique and very interesting as a solution to the power slip ring bearing issue that plagues classic SPS designs. Recent designs like the NASA butterfly tend to end up with a GEO fixed sandwich panel design of sorts, though SPS-ALPHA does the psuedo-cone arrangement, and the recent FISO presentation on Z step sandwich panel module research had a rather interesting central stepped cone arrangement replacing the traditional fixed flat disk of the NASA butterfly design (which is conceptually similar to this helix arrangement even if visually not so). Nice to see more people thinking beyond rectilinear 3D.

I guess you could also call it a heliogyro style of sorts...

But how does the GEO case work without relay mirrors like the NASA butterfly design, for a single satellite design? Wouldn't a 24 hour sun tracking spin to keep the PV panels lit also point the phased array primary axis so far off orthogonally that you would get terrible transmission efficiency?
Mirrors can be aluminum or another metal, if produced in space then there won't be any oxidisation. Plus it can be very thin and lite.



Sent from my SM-G570Y using Tapatalk

Title: Re: Solar Power Satellites
Post by: Robotbeat on 06/08/2017 04:02 am
I really don't care if terrestrial solar is better than solar power satellites.

Can we talk about the topic please?

34,000 tons sounds like fun. 100 ITS flights or 200 mini-ITS?
That's the thing about ITS:

Musk may think SBSP is dumb, but ITS actually gives it a shot at working.

And same with Bezos' New Armstrong, if it's competitive with ITS. And Bezos might actually BUILD it, since:
1) Bezos is way richer than Musk and will still be super rich after developing New Armstrong and
2) Bezos doesn't explicitly think SBSP is dumb; he talks a lot about moving industry off-planet, and energy production is one of (if not THE) largest.

Bezos could actually afford to finance a few full-sized SBSP stations himself, especially if he finds clever ways of leveraging his own cash (as all self-made billionaires tend to do).
Title: Re: Solar Power Satellites
Post by: Stan-1967 on 06/08/2017 04:17 am

1) Bezos is way richer than Musk and will still be super rich after developing New Armstrong and
2) Bezos doesn't explicitly think SBSP is dumb; he talks a lot about moving industry off-planet, and energy production is one of (if not THE) largest.

Bezos could actually afford to finance a few full-sized SBSP stations himself, especially if he finds clever ways of leveraging his own cash (as all self-made billionaires tend to do).

That lucky Bezos guy is going to retire as a millionaire if he jumps into SBSP.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 06/08/2017 04:31 am

1) Bezos is way richer than Musk and will still be super rich after developing New Armstrong and
2) Bezos doesn't explicitly think SBSP is dumb; he talks a lot about moving industry off-planet, and energy production is one of (if not THE) largest.

Bezos could actually afford to finance a few full-sized SBSP stations himself, especially if he finds clever ways of leveraging his own cash (as all self-made billionaires tend to do).

That lucky Bezos guy is going to retire as a millionaire if he jumps into SBSP.
Ya can't take it with you...

But I think you underestimate how rich Bezos is.
Title: Re: Solar Power Satellites
Post by: RocketmanUS on 06/08/2017 05:10 am
I really don't care if terrestrial solar is better than solar power satellites.

Can we talk about the topic please?

34,000 tons sounds like fun. 100 ITS flights or 200 mini-ITS?
That's the thing about ITS:

Musk may think SBSP is dumb, but ITS actually gives it a shot at working.

And same with Bezos' New Armstrong, if it's competitive with ITS. And Bezos might actually BUILD it, since:
1) Bezos is way richer than Musk and will still be super rich after developing New Armstrong and
2) Bezos doesn't explicitly think SBSP is dumb; he talks a lot about moving industry off-planet, and energy production is one of (if not THE) largest.

Bezos could actually afford to finance a few full-sized SBSP stations himself, especially if he finds clever ways of leveraging his own cash (as all self-made billionaires tend to do).
Solar power for use in space for industry use. Perhaps in the future solar from space for use on Earth might work , but for now I would say in space use. Products made in space for space use and for Earth.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 06/08/2017 05:51 am
I really don't care if terrestrial solar is better than solar power satellites.

Can we talk about the topic please?

34,000 tons sounds like fun. 100 ITS flights or 200 mini-ITS?
That's the thing about ITS:

Musk may think SBSP is dumb, but ITS actually gives it a shot at working.

And same with Bezos' New Armstrong, if it's competitive with ITS. And Bezos might actually BUILD it, since:
1) Bezos is way richer than Musk and will still be super rich after developing New Armstrong and
2) Bezos doesn't explicitly think SBSP is dumb; he talks a lot about moving industry off-planet, and energy production is one of (if not THE) largest.

Bezos could actually afford to finance a few full-sized SBSP stations himself, especially if he finds clever ways of leveraging his own cash (as all self-made billionaires tend to do).
Solar power for use in space for industry use. Perhaps in the future solar from space for use on Earth might work , but for now I would say in space use. Products made in space for space use and for Earth.
Not buying it unless you can be SPECIFIC. What would move a significant amount of industrial activity off planet? How many Gigawatts?
Title: Re: Solar Power Satellites
Post by: RocketmanUS on 06/08/2017 06:18 am
I really don't care if terrestrial solar is better than solar power satellites.

Can we talk about the topic please?

34,000 tons sounds like fun. 100 ITS flights or 200 mini-ITS?
That's the thing about ITS:

Musk may think SBSP is dumb, but ITS actually gives it a shot at working.

And same with Bezos' New Armstrong, if it's competitive with ITS. And Bezos might actually BUILD it, since:
1) Bezos is way richer than Musk and will still be super rich after developing New Armstrong and
2) Bezos doesn't explicitly think SBSP is dumb; he talks a lot about moving industry off-planet, and energy production is one of (if not THE) largest.

Bezos could actually afford to finance a few full-sized SBSP stations himself, especially if he finds clever ways of leveraging his own cash (as all self-made billionaires tend to do).
Solar power for use in space for industry use. Perhaps in the future solar from space for use on Earth might work , but for now I would say in space use. Products made in space for space use and for Earth.
Not buying it unless you can be SPECIFIC. What would move a significant amount of industrial activity off planet? How many Gigawatts?
NEA and Lunar mining, product for space exploration and living off Earth. Why make it on Earth when it would be used off Earth. For Earth based use, environmental issues making a product on Earth that could be made in space or mined in space without the environmental impact here on earth.

So that is how I would see large solar power used in space.
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/08/2017 10:05 am
IN THE INTERESTS OF PUBLIC DISCLOSURE:

CASSIOPeiA – Constant Aperture, Solid State, Integrated, Orbital Phased Array



I think I get the design, but is the helix central axis actively pointed at the sun, or are you willing to take the off-angle power efficiency loss to utilize passive pointing? Like Mankin's SPS-ALPHA, unless you have a lot of good orientation/beaming pictures, people will have trouble visualizing the arrangement and usage. If passive, would you also be using an upward tether mass to gravity gradient stabilize the nadir pointing of the phased array, or will you also be using active means to roll the helix to improve pointing at specific ground targets?

Ideally (at GSO), the helix axis is normal to the ecliptic. A dielectric mirror inclined at 45 degrees allows a CPV chip to be mounted on the same substrate as the electronics (with radiation shielding provided by the secondary  Kohler concentrator), and may be integrated with the triple-antenna arrangement which generates the steerable cardioid pattern. Thermal management is by simple heat spreading by the conductive layers within the substrate.

The comparison here is with a standard square planar array (having side D, no rear reflector/absorber) having the same number of RF elements, power and spacing. The side-view RF aperture of the array equals its solar collecting area, and is given by 2*D^2/pi

The RF surface intensity animation is modelled for a slightly larger array, as it rotates through 360 degrees of orbit (as seen from Earth), continuously and directly facing the sun (one physical rotation/year).

As can be seen, from a mass distribution POV, the design is rotationally symmetric (so no GG stabilisation). Attitude and maneuvering control is still required, though a means of using passive sunlight pressure to aid sun-pointing is being investigated.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 06/08/2017 01:21 pm
I really don't care if terrestrial solar is better than solar power satellites.

Can we talk about the topic please?

34,000 tons sounds like fun. 100 ITS flights or 200 mini-ITS?
That's the thing about ITS:

Musk may think SBSP is dumb, but ITS actually gives it a shot at working.

And same with Bezos' New Armstrong, if it's competitive with ITS. And Bezos might actually BUILD it, since:
1) Bezos is way richer than Musk and will still be super rich after developing New Armstrong and
2) Bezos doesn't explicitly think SBSP is dumb; he talks a lot about moving industry off-planet, and energy production is one of (if not THE) largest.

Bezos could actually afford to finance a few full-sized SBSP stations himself, especially if he finds clever ways of leveraging his own cash (as all self-made billionaires tend to do).
Solar power for use in space for industry use. Perhaps in the future solar from space for use on Earth might work , but for now I would say in space use. Products made in space for space use and for Earth.
Not buying it unless you can be SPECIFIC. What would move a significant amount of industrial activity off planet? How many Gigawatts?
NEA and Lunar mining, product for space exploration and living off Earth. Why make it on Earth when it would be used off Earth. For Earth based use, environmental issues making a product on Earth that could be made in space or mined in space without the environmental impact here on earth.

So that is how I would see large solar power used in space.
No, still not specific enough. Again, what product or mineral or whatever are you proposing to make industrially off-Earth that significantly would reduce impact on Earth, and how many Gigawatts does this replace?
Title: Re: Solar Power Satellites
Post by: gongora on 06/08/2017 10:34 pm
Split recent earth vs. space solar posts into separate thread:
Earth Solar vs. Solar Power Satellites (http://forum.nasaspaceflight.com/index.php?topic=43103.0)
Title: Re: Solar Power Satellites
Post by: Asteroza on 06/09/2017 01:22 am
IN THE INTERESTS OF PUBLIC DISCLOSURE:

CASSIOPeiA – Constant Aperture, Solid State, Integrated, Orbital Phased Array



I think I get the design, but is the helix central axis actively pointed at the sun, or are you willing to take the off-angle power efficiency loss to utilize passive pointing? Like Mankin's SPS-ALPHA, unless you have a lot of good orientation/beaming pictures, people will have trouble visualizing the arrangement and usage. If passive, would you also be using an upward tether mass to gravity gradient stabilize the nadir pointing of the phased array, or will you also be using active means to roll the helix to improve pointing at specific ground targets?

Ideally (at GSO), the helix axis is normal to the ecliptic. A dielectric mirror inclined at 45 degrees allows a CPV chip to be mounted on the same substrate as the electronics (with radiation shielding provided by the secondary  Kohler concentrator), and may be integrated with the triple-antenna arrangement which generates the steerable cardioid pattern. Thermal management is by simple heat spreading by the conductive layers within the substrate.

The comparison here is with a standard square planar array (having side D, no rear reflector/absorber) having the same number of RF elements, power and spacing. The side-view RF aperture of the array equals its solar collecting area, and is given by 2*D^2/pi

The RF surface intensity animation is modelled for a slightly larger array, as it rotates through 360 degrees of orbit (as seen from Earth), continuously and directly facing the sun (one physical rotation/year).

As can be seen, from a mass distribution POV, the design is rotationally symmetric (so no GG stabilisation). Attitude and maneuvering control is still required, though a means of using passive sunlight pressure to aid sun-pointing is being investigated.


My RF literacy is not great, so I need to check something here. The three dipole antennas of a single transmission module all control of the beam such that you can transmit in any desired radial direction around an axis normal to the module "plate", correct? What does the radiation pattern look like in the other 2 axis (aka normal to the plate)?

Your original helix image shows what appear to be transmit plate squares hanging off the PV vanes like sub-fins, with all the plates aligned to make a single virtual flat plate that shares the same normal axis as the individual plates.

So, is the actual primary beam direction coming from the virtual flat plate normal axis ideally, or does it come from the side of the virtual plate? I guess I am asking if the correct ground orientation is a visually blocking plate like the upper left view of the helix model picture, or the mostly see through view of the lower left.

I get the feeling the helix design is more different between an SSO type and a GEO/GSO type, due to the pointing needs of the structure if the 45 degree mirror is fixed.
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/12/2017 09:01 am
...The three dipole antennas of a single transmission module all control of the beam such that you can transmit in any desired radial direction around an axis normal to the module "plate", correct? What does the radiation pattern look like in the other 2 axis (aka normal to the plate)?

If you take the polar radiation pattern of an ideal vertical half-wave dipole, it is omnidirectional in azimuth (360 degrees), and like a figure 8 on its side (or infinity symbol) in elevation. CASSIOPeiA has an equivalent high-gain beaming capability: 360 degrees azimuth and +/-55 degrees in elevation. This capability arises through the combination of each element able to steer a cardioid pattern (in azimuth), and the distribution of these elements across a helical surface having constant aperture from any side view.

I've superimposed the ideal dipole pattern (in grey) and results from a small model CASSIOPeiA on the same polar plots. The peak intensity drops by half at +/- 55 degrees elevation. The azimuth plot includes beam sweeps at both 0 and 55 degrees elevation*.

Quote
Your original helix image shows what appear to be transmit plate squares hanging off the PV vanes like sub-fins, with all the plates aligned to make a single virtual flat plate that shares the same normal axis as the individual plates.

So, is the actual primary beam direction coming from the virtual flat plate normal axis ideally, or does it come from the side of the virtual plate? I guess I am asking if the correct ground orientation is a visually blocking plate like the upper left view of the helix model picture, or the mostly see through view of the lower left.

The "transmit plate squares" are actually the polymer Fresnel lenses (transparent to microwaves). The diagram shows how the actual triple dipoles (one RF element) can be integrated with the concentrating photovoltaic  (CPV) optics without shadowing.

The relationship between CPV and RF elements is not always 1:1, but follows the sine of the angle each layer makes with the sun. At middle layers, this angle is 90 degrees, hence full coverage by CPV optics, at outer layers the angle (and hence CPV coverage) approaches zero. RF element coverage, however, is essentially uniform across the array, with (at-most) half-wavelength separation to neighbouring elements to avoid grating lobes.

Quote
I get the feeling the helix design is more different between an SSO type and a GEO/GSO type, due to the pointing needs of the structure if the 45 degree mirror is fixed.

The helix design remains the same, however the concentrating optics may differ (such as using compound parabolic concentration - CPC) to allow a wider solar acceptance angle (*at the expense of optical concentration) - this will likely be the case for the stratospheric version where roll/yaw angles may be harder to maintain.

[*Edits for clarification]
Title: Re: Solar Power Satellites
Post by: Asteroza on 06/13/2017 02:02 am
...The three dipole antennas of a single transmission module all control of the beam such that you can transmit in any desired radial direction around an axis normal to the module "plate", correct? What does the radiation pattern look like in the other 2 axis (aka normal to the plate)?

If you take the polar radiation pattern of an ideal vertical half-wave dipole, it is omnidirectional in azimuth (360 degrees), and like a figure 8 on its side (or infinity symbol) in elevation. CASSIOPeiA has an equivalent high-gain beaming capability: 360 degrees azimuth and +/-55 degrees in elevation. This capability arises through the combination of each element able to steer a cardioid pattern (in azimuth), and the distribution of these elements across a helical surface having constant aperture from any side view.

I've superimposed the ideal dipole pattern (in grey) and results from a small model CASSIOPeiA on the same polar plots. The peak intensity drops by half at +/- 55 degrees elevation. The azimuth plot includes beam sweeps at both 0 and 55 degrees elevation*.

Quote
Your original helix image shows what appear to be transmit plate squares hanging off the PV vanes like sub-fins, with all the plates aligned to make a single virtual flat plate that shares the same normal axis as the individual plates.

So, is the actual primary beam direction coming from the virtual flat plate normal axis ideally, or does it come from the side of the virtual plate? I guess I am asking if the correct ground orientation is a visually blocking plate like the upper left view of the helix model picture, or the mostly see through view of the lower left.

The "transmit plate squares" are actually the polymer Fresnel lenses (transparent to microwaves). The diagram shows how the actual triple dipoles (one RF element) can be integrated with the concentrating photovoltaic  (CPV) optics without shadowing.

The relationship between CPV and RF elements is not always 1:1, but follows the sine of the angle each layer makes with the sun. At middle layers, this angle is 90 degrees, hence full coverage by CPV optics, at outer layers the angle (and hence CPV coverage) approaches zero. RF element coverage, however, is essentially uniform across the array, with (at-most) half-wavelength separation to neighbouring elements to avoid grating lobes.

Quote
I get the feeling the helix design is more different between an SSO type and a GEO/GSO type, due to the pointing needs of the structure if the 45 degree mirror is fixed.

The helix design remains the same, however the concentrating optics may differ (such as using compound parabolic concentration - CPC) to allow a wider solar acceptance angle (*at the expense of optical concentration) - this will likely be the case for the stratospheric version where roll/yaw angles may be harder to maintain.

[*Edits for clarification]

Now it's starting to make sense! So if I understand correctly now, the dipoles are on the vanes (and normal to the vane), thus the beam covers 360 about the helix axis, and the virtual antenna provides some steering about the "face" of the antenna to track a ground target. So for GSO, the helix axis is normal to the ecliptic, and depending on the fresnel lens panels and and 45 degree mirrors, there might be some shadowing but usually not.

Couldn't you cheat a bit with the 45 degree mirror by changing to a half fresnel lens focusing to a spot just above the CPV cell, and place a much smaller 45 degree mirror there for the final turn?

However for the SSO case, if the helix axis is aligned to the ecliptic to allow easy ground tracking, would you essentially have fresnel lens sheets above the CPV that are coplanar to the vane?
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/15/2017 12:38 pm
Now it's starting to make sense! So if I understand correctly now, the dipoles are on the vanes (and normal to the vane), thus the beam covers 360 about the helix axis, and the virtual antenna provides some steering about the "face" of the antenna to track a ground target. So for GSO, the helix axis is normal to the ecliptic, and depending on the fresnel lens panels and and 45 degree mirrors, there might be some shadowing but usually not.

The centre-feed points of the triple dipoles are located on the substrate (shown horizontal - this could be what you mean by "vanes"), spaced one-quarter wavelength apart from each other (12.9mm for 5.8GHz). These can fit around the concentrating optics where necessary, as shown in the diagram.

Yes, the beam can steer 360 degrees about the helix axis, which is typically at 90 degrees (normal) to the ecliptic plane. It can also steer +/-55 degrees with respect to this plane, only a fraction of which would be required from ~5 Earth radii distance (36,000 km, GSO).

There should be no self shadowing by the lenses; each directly faces the Sun, with no overlap from the Sun's viewpoint. There will be some area-fill efficiency losses due to the thin substrate and lens edges.

"virtual antenna"??

Quote
Couldn't you cheat a bit with the 45 degree mirror by changing to a half fresnel lens focusing to a spot just above the CPV cell, and place a much smaller 45 degree mirror there for the final turn?

The concentrating optics are non imaging, but the "focal point" has to be fixed with respect to the Kohler concentrator and CPV for even illumination across its surface.

Quote
However for the SSO case, if the helix axis is aligned to the ecliptic to allow easy ground tracking, would you essentially have fresnel lens sheets above the CPV that are coplanar to the vane?

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

You are correct that the 45 degrees planar mirror angle could differ for each of the offset orbits, should the helix axis not remain normal to the Sun-line (the latter being my preference). Alternatively the optics could change to a compound parabolic concentrator configuration (lower concentration, but wider solar acceptance angle). The CPC would also comprise a dielectric reflector to avoid interference with the microwaves.
Title: Re: Solar Power Satellites
Post by: Asteroza on 06/19/2017 12:00 am

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

Constellation layout similar to a molniya or tundra orbit then? But why 5?
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/19/2017 11:55 am

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

Constellation layout similar to a molniya or tundra orbit then? But why 5?

Starting small, a station-keeping pseudo-satellite in the stratosphere gives many of the same advantages as geostationary - i.e. its always visible over a fixed point on Earth throughout 24 hours. The disadvantage is that the stratosphere is still subject to the day/night cycle, whereas Earth's shadow is mostly avoided by a satellite at GSO/GEO (exception is daily outages of a few ten's of minutes around the spring and autumn equinox).

This particular set of 3-hour sun-synchronous orbits is a compromise; it allows satellites approximately 1/5 the mass to feasibly be deployed as a single payload (given future ITS-scale heavy-lift), without complex on-orbit construction. Modelling has shown that a rectenna situated at latitudes north of 45 degrees can switch between satellites to maintain >23 hours power output (i.e. predictable, near-baseload power which repeats daily throughout the year, including mid-winter where the "red" satellite still skips over Earth's shadow, as shown).

What hasn't been proven yet is that this should also be possible simultaneously for a second rectenna (at similar latitude) half-way around the globe.

Without 5 satellites, the rectenna utlisation is much less.

I've previously looked at Molniya for the HESPeruS SPS - it was the most feasible orbit for a solid-state satellite (no moving/rotating parts) given the beam steer limitations of a phased array. It had much reduced mass (and requires less delta-vee), but still had to be very large to focus a beam from 40,000km to northern latitudes only.

CASSIOPeiA doesn't have these beam-steer limitations! It is a new arrangement of phased array able to steer a beam through 360 degrees azimuth and +/-55 degrees elevation, suitable for any orbit (hence the patent application for a Constant Aperture, Solid State, Integrated, Orbital Phased Array).
Title: Re: Solar Power Satellites
Post by: Asteroza on 06/19/2017 11:05 pm

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

Constellation layout similar to a molniya or tundra orbit then? But why 5?

Starting small, a station-keeping pseudo-satellite in the stratosphere gives many of the same advantages as geostationary - i.e. its always visible over a fixed point on Earth throughout 24 hours. The disadvantage is that the stratosphere is still subject to the day/night cycle, whereas Earth's shadow is mostly avoided by a satellite at GSO/GEO (exception is daily outages of a few ten's of minutes around the spring and autumn equinox).

This particular set of 3-hour sun-synchronous orbits is a compromise; it allows satellites approximately 1/5 the mass to feasibly be deployed as a single payload (given future ITS-scale heavy-lift), without complex on-orbit construction. Modelling has shown that a rectenna situated at latitudes north of 45 degrees can switch between satellites to maintain >23 hours power output (i.e. predictable, near-baseload power which repeats daily throughout the year, including mid-winter where the "red" satellite still skips over Earth's shadow, as shown).

What hasn't been proven yet is that this should also be possible simultaneously for a second rectenna (at similar latitude) half-way around the globe.

Without 5 satellites, the rectenna utlisation is much less.

I've previously looked at Molniya for the HESPeruS SPS - it was the most feasible orbit for a solid-state satellite (no moving/rotating parts) given the beam steer limitations of a phased array. It had much reduced mass (and requires less delta-vee), but still had to be very large to focus a beam from 40,000km to northern latitudes only.

CASSIOPeiA doesn't have these beam-steer limitations! It is a new arrangement of phased array able to steer a beam through 360 degrees azimuth and +/-55 degrees elevation, suitable for any orbit (hence the patent application for a Constant Aperture, Solid State, Integrated, Orbital Phased Array).

For a multisite requirement, would you favor 3 tundra orbits with 2-3 sats each to provide high latitude global coverage (something like the QZSS layout, but with three figure 8 footprints)?
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/20/2017 10:24 am

You don't need CASSIOPeiA in a typical Sun-synchronous dusk/dawn orbit; a conventional design (but without rotating joints) can point continuously at the sun, while rotating every 100mins-or-so about a sun-pointing axis to keep a conventional antenna within beam-steer limits of the Earth target. The axis then needs to shift roughly 1 degree/day to maintain sun-pointing. Unfortunately this orbit is incapable of delivering high rectenna utilisation without a very large constellation.

I'm proposing a different 5-SPS, Sun-synchronous 3-hour elliptical orbit (in one-case), offering >23 hours baseload power to northern latitudes, and possibly to more than one rectenna simultaneously (I have not run the simulation yet for multiple rectenna sites), certainly with intermittent beaming to other rectenna sites at any latitude; the globe and map projections show a period where the "red" satellite's beam footprint covers anywhere within the African continent whilst the "orange" satellite covers North America, for example.

Constellation layout similar to a molniya or tundra orbit then? But why 5?

Starting small, a station-keeping pseudo-satellite in the stratosphere gives many of the same advantages as geostationary - i.e. its always visible over a fixed point on Earth throughout 24 hours. The disadvantage is that the stratosphere is still subject to the day/night cycle, whereas Earth's shadow is mostly avoided by a satellite at GSO/GEO (exception is daily outages of a few ten's of minutes around the spring and autumn equinox).

This particular set of 3-hour sun-synchronous orbits is a compromise; it allows satellites approximately 1/5 the mass to feasibly be deployed as a single payload (given future ITS-scale heavy-lift), without complex on-orbit construction. Modelling has shown that a rectenna situated at latitudes north of 45 degrees can switch between satellites to maintain >23 hours power output (i.e. predictable, near-baseload power which repeats daily throughout the year, including mid-winter where the "red" satellite still skips over Earth's shadow, as shown).

What hasn't been proven yet is that this should also be possible simultaneously for a second rectenna (at similar latitude) half-way around the globe.

Without 5 satellites, the rectenna utlisation is much less.

I've previously looked at Molniya for the HESPeruS SPS - it was the most feasible orbit for a solid-state satellite (no moving/rotating parts) given the beam steer limitations of a phased array. It had much reduced mass (and requires less delta-vee), but still had to be very large to focus a beam from 40,000km to northern latitudes only.

CASSIOPeiA doesn't have these beam-steer limitations! It is a new arrangement of phased array able to steer a beam through 360 degrees azimuth and +/-55 degrees elevation, suitable for any orbit (hence the patent application for a Constant Aperture, Solid State, Integrated, Orbital Phased Array).

For a multisite requirement, would you favor 3 tundra orbits with 2-3 sats each to provide high latitude global coverage (something like the QZSS layout, but with three figure 8 footprints)?

Yes, it would also work in Tundra and other similar 24 hour orbits, but both the transmitter (CASSIOPeiA) and rectenna sizes would need to grow to accommodate the greater apogee (wrt GEO), yet still deliver 50W/m^2 mean, 230W/m^2 safe peak beam intensity at the intended site.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 06/20/2017 12:51 pm
That's really low.

I've often thought that if SBSP will ever be worthwhile, they have to up the beam intensity to greater than sunlight to reduce the footprint.
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/20/2017 12:54 pm
Split recent earth vs. space solar posts into separate thread:
Earth Solar vs. Solar Power Satellites (http://forum.nasaspaceflight.com/index.php?topic=43103.0)
Gongora / Other-Mods - do you know what's happened to this thread (Earth Solar vs. Solar Power Satellites)?
Title: Re: Solar Power Satellites
Post by: SICA Design on 06/20/2017 01:04 pm
That's really low.

I've often thought that if SBSP will ever be worthwhile, they have to up the beam intensity to greater than sunlight to reduce the footprint.

It's an environmentally acceptable level (NASA/other research - no impact to wildlife passing through the beam, safe for passenger carrying aircraft), far greater (x10 typical) mean power/area than any terrestrial solar farm.

It also offers reassurance that an SPS can't be turned into a space weapon - physical law dictates the peak beam intensity given transmitter aperture (e.g. 1.43km diameter, *projected area being equal to the solar collector), frequency (5.8 GHz is optimum available, >>10GHz is severely attenuated by atmosphere) and distance (e.g. 36,000 km GEO).

[Edit: Clarified RF aperture = Solar Collector area, for the CASSIOPeiA concept, hence peak intensity also limited by the available power, 1365 W/m^2, and the CPV efficiency, 30% - 45%] 
Title: Re: Solar Power Satellites
Post by: QuantumG on 06/20/2017 11:16 pm
That's really low.

I've often thought that if SBSP will ever be worthwhile, they have to up the beam intensity to greater than sunlight to reduce the footprint.

There are SBSP schemes that basically just try to solve the Sun-at-night problem of terrestrial solar. The dumbest being the space-mirrors idea.
Title: Re: Solar Power Satellites
Post by: Lar on 06/21/2017 12:46 am
Split recent earth vs. space solar posts into separate thread:
Earth Solar vs. Solar Power Satellites (http://forum.nasaspaceflight.com/index.php?topic=43103.0)
Gongora / Other-Mods - do you know what's happened to this thread (Earth Solar vs. Solar Power Satellites)?

Investigating this ... it may not be back, it got kind of snarky.  But usually a PM is the way to go when wondering these sorts of things.
Title: Re: Solar Power Satellites
Post by: QuantumG on 06/21/2017 01:02 am
Investigating this ... it may not be back, it got kind of snarky.  But usually a PM is the way to go when wondering these sorts of things.

Seeing as we're talking about it... I don't really care if the thread comes back, but I will report-to-mod all attempts to bring that snarkiness back here.
Title: Re: Solar Power Satellites
Post by: Nilof on 07/08/2017 06:32 pm
Personally I don't think I agree with low power beam designs. A beam with a spot size of ~10 meters and an average intensity of 100 solar constants is much more useful, since you can have them power vehicles such as boats or aircraft which pay more per kW of energy since they can not feasibly be connected to the grid. High power density SSP's are still less of an issue than concentrated solar thermal farms as far as birds or aircraft go. You could even put receivers on tethered high-altitude balloons if you're really that worried.

I don't see much point in space solar power if it's just "sunlight at night" unless you manage to make launches that much cheaper than batteries.
Title: Re: Solar Power Satellites
Post by: Asteroza on 07/09/2017 11:40 pm
Personally I don't think I agree with low power beam designs. A beam with a spot size of ~10 meters and an average intensity of 100 solar constants is much more useful, since you can have them power vehicles such as boats or aircraft which pay more per kW of energy since they can not feasibly be connected to the grid. High power density SSP's are still less of an issue than concentrated solar thermal farms as far as birds or aircraft go. You could even put receivers on tethered high-altitude balloons if you're really that worried.

I don't see much point in space solar power if it's just "sunlight at night" unless you manage to make launches that much cheaper than batteries.

Certainly an economic case can be made for large vehicles and fixed remote sites that require small receivers as early customers for bootstrapping. Notably, military forward bases and small islands, both of which pay through the nose for power, and both have little land reservable for large rectennas. Though that then pushes into laser territory due to the physics of it all, which is fine by me as a laser system allows launcher upgrades that accelerate bootstrapping. I have a dislike about having to weaken system designs for political purposes, but infrastructure projects by their nature are political in nature, so you're damned if do, damned if you don't.
Title: Re: Solar Power Satellites
Post by: QuantumG on 07/09/2017 11:55 pm
I don't see much point in space solar power if it's just "sunlight at night" unless you manage to make launches that much cheaper than batteries.

Well, it's obviously not just batteries... even if you had 12 hour days you'd need over double the generation capacity (as the batteries have losses) and typically more than that... and as I keep saying, the real win of space solar power is for the people living in space. Neither energy farms, nor space projects are good investments. If your goal is to make money, go make a Facebook game or whatever.

If you want people living and working in space, selling sunlight is a pretty good business for them.

Title: Re: Solar Power Satellites
Post by: TrevorMonty on 07/10/2017 11:54 am
I don't see much point in space solar power if it's just "sunlight at night" unless you manage to make launches that much cheaper than batteries.

Well, it's obviously not just batteries... even if you had 12 hour days you'd need over double the generation capacity (as the batteries have losses) and typically more than that... and as I keep saying, the real win of space solar power is for the people living in space. Neither energy farms, nor space projects are good investments. If your goal is to make money, go make a Facebook game or whatever.

If you want people living and working in space, selling sunlight is a pretty good business for them.
Beaming power by laser to lunar rovers and outposts could well be first use. For rovers even a few 100watts is all that is needed every few hours to operate through lunar night. Radio telescopes would also need power for lunar night.

Title: Re: Solar Power Satellites
Post by: TrevorMonty on 01/03/2018 03:26 am


http://www.minesnewsroom.com/news/lange-studying-feasibility-space-based-solar-power

“The two markets that everyone is interested in as far as space-based solar power is advanced deployment of military units and remote mining operations,” Lange said. 

You can also add space mining operations to that list, especially lunar mines.

Title: Re: Solar Power Satellites
Post by: bolun on 06/02/2018 09:08 am
30% efficiency solar cell

Solar cells have a hard life in space – their efficiency at converting sunlight into energy at the end of their time there is more prized than their initial efficiency. This next generation solar cell having an area of around 30 sq. cm boosts the beginning of life efficiency of up to 30.9% and end of life efficiency to 27.5% - and in the future designers expect to push this figure above 30%.

Developed for ESA by a consortium led by German solar cell manufacturer Azur Space, CESI in Italy, Germany’s Fraunhofer Institute for Solar Energy Systems, Qioptiq in the UK, Umicore in Belgium, tf2 devices in the Netherlands, and Finland’s Tampere University of Technology, this design is a ‘four-junction’ 0.1 mm-thick device containing four layers of different materials (AlGaInP, AlGaInAs, GaInAs,Ge) to absorb separate wavelengths of sunlight.

This design was originated through ESA’s Technology Research Programme with further development and qualification testing supported through the Agency’s ARTES, Advanced Research in Telecommunications Systems, programme. It is currently intended to fly with ESA’s next generation Neosat telecom satellites.

https://www.esa.int/spaceinimages/Images/2018/05/30_efficiency_solar_cell

Image credit: Azur Space
Title: Re: Solar Power Satellites
Post by: Tywin on 11/09/2019 04:58 pm
Look like we have a new revolution with the fabrication of solar cells in space:

Quote
Engineers Lyndsey McMillon-Brown and Timothy Peshek are leading a project to test perovskite solar cells, which could be an alternative to silicon solar cells currently used in space. This material is a relatively new discovery, and it has many advantages for solar technology. Not only is perovskite an incredible conductor of electricity, but it also can be transported into space as a liquid and then printed onto panels on the Moon or Mars, unlike silicon panels that have to be built on Earth and then shipped to space.

“It’s a build as you go process,” said McMillon-Brown. “Perovskites have a nice versatility we haven’t yet seen. In a short period, there have been rapid advancements in its efficiencies and its behavior. We’ve seen a lot of growth in this field.”


https://www.nasa.gov/feature/glenn/2019/building-solar-panels-in-space-might-be-as-easy-as-clicking-print

With the new reusable rockets, like FH, and future New Glenn, and later the Starship...the Solar Power Station, start to be something we have big chances to be reality in the next decades...
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/10/2019 11:59 am
Need structure to support solar array panels/fabric. Also conductors to carry power and large transmitter dish. Mass adds up quickly and it all needs to be delivered to GEO.

Still need most of these materials source from moon or asteriods. Good news is cheaper launch costs means its cheap to setup and maintain these space mining operation.
Title: Re: Solar Power Satellites
Post by: gongora on 11/10/2019 09:55 pm
U.S. Air Force Research Laboratory Developing Space Solar Power Beaming (https://www.edwards.af.mil/News/Article/1998062/us-air-force-research-laboratory-developing-space-solar-power-beaming/)
By Kirtland Public Affairs, Air Force Reasearch Laboratory / Published October 24, 2019

KIRTLAND AIR FORCE BASE, N.M. --
The Air Force Research Laboratory is developing space-based solar power transmission capability using high-efficiency solar cells to collect the sun’s energy, convert it to radio frequency, and beam it to earth.

“Energy is a strategic enabler and potential vulnerability for our nation and our Department of Defense” said U.S. Air Force Col. Eric Felt, director of AFRL’s Space Vehicles Directorate. “To ensure DoD mission success we must have the energy we need at the right place at the right time.”

Providing uninterrupted, assured, and agile power to expeditionary forces operating in unimproved areas such as forward operating bases would provide an advantage to U.S. and allied forces.

“The Space Solar Power Incremental Demonstrations and Research (SSPIDR) Project is a very interesting concept that will enable us to capture solar energy in space and precisely beam it to where it is needed,” Felt said. “SSPIDR is part of AFRL’s ‘big idea pipeline’ to ensure we continue to develop game-changing technologies for our Air Force, DoD, nation, and world.”

AFRL researchers are focused on developing and demonstrating some of the key technologies necessary to integrate into a conceptual space-based power beaming system. Northrop Grumman will partner with AFRL and has been awarded a contract valued at more than $100 million to develop and deliver the critical hardware elements to support space-based experiments into this leading-edge technology.

Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/10/2019 11:44 pm
Nice to see somebody is actively working on this. While technically possible nobody has actually flown satellite and beamed power back to earth.
Title: Re: Solar Power Satellites
Post by: edzieba on 11/11/2019 12:17 pm
Regardless of SBSP's economic viability for general consumer use, military use is a definitely use case where it's not so hard to be cheaper and more reliable than trucking fuel via literal truck through the middle of a warzone.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/11/2019 03:59 pm
This video maybe how they plan to design satellites. Northrop Grumman are major sponser of this Caltech project.

https://youtu.be/em8T1nOL0tM

The usual SBSP designs meant building huge satellite in GEO, something we can't do at present. They've approached idea from different angle by using lots of small individual satellites that can join up to scale up, these operate in MEO. They think $2kwh is possible which is lot cheaper than current $10-15 for some miltary outposts.

With miltary outposts fuel transport costs are lot higher than normal as its transported by convoy or air. Both very expensive.

The constellation idea means they can provide power to lot locations around the global. One possible business model (my idea) is miltary will pay minimum amount year for so much power with option to buy more at other locations covered by constellation. Constellation operator can sell surplus power to civilian customers in other locations where miltary don't need it. Eg  $5kwh to base in Iraq and $1 to mining operation in Australia outback, $2 to Arctic  site, ie whatever price market at these locations will tolerate.

Not sure of cost of building large ground receiving stations.

Title: Re: Solar Power Satellites
Post by: TripleSeven on 11/11/2019 04:23 pm
This video maybe how they plan to design satellites. Northrop Grumman are major sponser of this Caltech project.

https://www.youtube.com/watch?v=em8T1nOL0tM

The usual SBSP designs meant building huge satellite in GEO, something we can't do at present. They've approached idea from different angle by using lots of small individual satellites that can join up to scale up, these operate in MEO. They think $2kwh is possible which is lot cheaper than current $10-15 for some miltary outposts.

With miltary outposts fuel transport costs are lot higher than normal as its transported by convoy or air. Both very expensive.

The constellation idea means they can provide power to lot locations around the global. One possible business model (my idea) is miltary will pay minimum amount year for so much power with option to buy more at other locations covered by constellation. Constellation operator can sell surplus power to civilian customers in other locations where miltary don't need it. Eg  $5kwh to base in Iraq and $1 to mining operation in Australia outback, $2 to Arctic  site, ie whatever price market at these locations will tolerate.

Not sure of cost of building large ground receiving stations.

I just finished watching the entire video...this is quite interesting. 

I was in Iraq for almost 4 years...I think he is LOW on the cost of electrical energy...its more like 20 a KW hour when EVERYTHING is taken into account including trucks blown up etc...and of course that does not take into account the lives.  if he can get it down to those numbers...its fascinating
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/11/2019 08:00 pm
The prices were based on Atlas launch costs, SpaceX Starship should reduce those by factor of 5. With 9m fairing to work with satellite construction should also be cheaper.

I doubt they will ever compete with domestic prices of 20c but there is huge world wide market in $0.50-1.0 price range. Lots of communities and mining operations run on diesel generators with expensive shipping costs.
Title: Re: Solar Power Satellites
Post by: Asteroza on 11/11/2019 10:28 pm
There's also the factor that the military may be entirely fine with a laser SPS, which changes a number of parameters (notably transmitter size, receiver size).
Title: Re: Solar Power Satellites
Post by: CameronD on 11/11/2019 11:21 pm
I doubt they will ever compete with domestic prices of 20c but there is huge world wide market in $0.50-1.0 price range. Lots of communities and mining operations run on diesel generators with expensive shipping costs.

And they would still have to to get the required up-time, given SBSP presumably won't work through severe weather events.

Has anyone actually tried beaming power from space to earth to see if it actually works (efficiently, economically)?  All these numbers being bandied around for something that hasn't been properly tested in real-world conditions makes it seem to me that their TRL is around the same level as Space Elevators - and has been for years.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/12/2019 04:14 am
Microwaves should work in any weather, maybe some losses in severe weather, but not significant.

No one has tested power beaming from space, but in say that most of GEO sats are transmitting data to earth via microwave so its not totally unproven.

Lasers make for smaller simpler receiver but need clear skies and pointing of laser is more difficult as its mechanical. Also higher losses even in clear skies. The proposal above uses electronic pointing of microwave beam.
Title: Re: Solar Power Satellites
Post by: CameronD on 11/12/2019 04:42 am
Microwaves should work in any weather, maybe some losses in severe weather, but not significant.

No one has tested power beaming from space, but in say that most of GEO sats are transmitting data to earth via microwave so its not totally unproven.

IIRC, low-power microwave radio signals get routinely dropped passing through clouds containing high levels of moisture (rain), but get re-established shortly after the cloud (or the satellite) has moved.  I foresee issues with beaming high-power microwaves from a stationary platform because (a) if the beam is high power enough it could cause local heating of the cloud making the cloud thicker and the absorption problem worse, (b) you're not moving so you can't re-establish the beam at a different angle and (c) can really high power microwave radiation trigger lightning events?.. but I'm happy to be wrong on all this.  :)
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/12/2019 08:27 am
Power beaming is targeting lower frequencies that have less losses from heavy rain than communication system's higher frequencies.
Title: Re: Solar Power Satellites
Post by: CameronD on 11/13/2019 09:32 pm
Power beaming is targeting lower frequencies that have less losses from heavy rain than communication system's higher frequencies.

Not sure that's true.  The ideal for power beaming is to use as high a frequency as possible (hence the proposals around using lasers) because lower frequency means greater beam spread and hence greater losses.

Like many things, it's a trade-off - and the best solution would probably use a spread-spectrum system of some kind - however the other aspect then is licensing: somehow you'd need to get approval for the block of frequencies you'd like to use (most of which I suspect are currently in use by earth imaging/remote sensing satellites for the same cloud-penetration reasons you'd want them for power beaming) in various countries not necessarily under the control of the FCC and I'd think that in itself might be a significant road-block to this tech.

It'll be interesting to see how many more decades it takes for SBSP to become reality.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/13/2019 11:06 pm
Good point about radio spectrum licensing.
Title: Re: Solar Power Satellites
Post by: ulm_atms on 11/13/2019 11:36 pm
Nice to see somebody is actively working on this. While technically possible nobody has actually flown satellite and beamed power back to earth.

Well, in all truthfulness, we have all ready been doing it for decades actually.  We have just been transmitting very very small amounts of power and encode data into it's waveform.  A really good example is an old crystal AM radio.  It has no power source at all.  It uses the power of the RF signal to power the circuit to make sound.  The carrier signal is the power and the amplitude modulation is the data.

All this is doing is turning up the transmit power to something that is more useful then just the data in the waveform.  There is zero difference in physics between RF for communication and RF for power distribution....only the scale of the transmitted power.
Title: Re: Solar Power Satellites
Post by: MKrob89 on 11/15/2019 04:19 pm
TBH I used to be a big fan of space solar power until I discovered stratospheric solar power.
It could be though of as a halfway house between ground level and space solar, but the costs can actually be much lower (hardware/watt) than ground level (as cell encapsulation is trivially simple when there is no rain, dust, or hail, and by using inflatable hexagon shaped packaging film saucer style balloons tethered using polyester tire cord based tethers, the hardware costs are as low as 25% of the cell costs).
Meanwhile, there is no power beaming required (tethers cords wrapped in anodised aluminium to carry current), the land below is usable (panels are 20km up and <8km diameter, so light loss is quite minimal, and crop growth is nonlinear with light loss - up to 80% normal growth with 50% light seems common), and it also has almost all the usual benefits of space solar power - reliability, output, etc. There is "just" a factor of 1/pi or so, so it generates about 32% of the energy of a space solar system that is kept aimed at the sun 24/7. This is counteracted by the efficiency losses of power beaming, so the factor becomes close to 50% with realistic assumptions.
Of course the elephant in the room is that storage is required to expand the output to 24 hours. However, this is much easier to solve with battery storage than is the case with normal solar power, as the daily output is entirely predictable, so only around 14 hours of storage are required. With the much hyped tesla lithium cell grid storage this would work out with a LCOE around $65/Mwhr currently (assuming 7% discount rate, and accounting for lifetime and recycling of materials at end of life), so rather too high (and the price doesnt seem to be dropping nearly as quickly as Musk has claimed, aiui its currently going for $295/kwh, this is in addition to the question of lithium availability for large scale roll out of grid storage), but there are plenty of alternatives to lithium ion, e.g. even advanced lead acid is better, LCOE for the Rolls 5000 series is around $45/Mwhr. Then there are the Na-S grid storage modules available off the shelf from NGK, but no current prices seem to be available. There is a quote from 2014 that is below $300/kwhr, and the material costs are extremely low, so it seems reasonable that Na-S could drop in price massively, and recent large scale installations of the NGK modules in the UAE suggest it is very competitive (at least with lithium). Looking further out, MnO2/Zn cells have been demonstrated to over 5000 cycles in the lab, and use only commodity materials and minimal complex processing, with LCOE estimated below $20/Mwhr.
I've recently been modelling stratospheric solar at UK latitude: with 20km altitude and using typical UK demand curve, a 100% stratospheric solar power + storage at LCOE $20/Mwhr solution comes in at under $30/Mwhr accounting for all costs (grid tie inverter, 20 year lifetime of panels and balloons, and accounting for recycling costs). I doubt that space solar power could be this cheap with realistic cost models, but maybe I am wrong...

There is a company currently working on stratospheric solar power - stratosolar inc.  They have a few patents, but their patents are limited to quite specific implementations, and they dont seem to have made much progress. They are also wedded to a gravity based energy storage idea which seems to have dubious economic merits to me, and involves suspending multi hundred tonne concrete weights in the stratosphere...

Something stratosolar dont discuss is icing of the tether lines. This is surely obvious and the omission seems suspicious...
There are a few solutions, and I'm currently working on a patent application related to this issue, so I'm not going to spill the beans!
Title: Re: Solar Power Satellites
Post by: MKrob89 on 11/15/2019 08:50 pm
Okay I tried some economic modelling of three space solar power sats in Molniya orbits.
 If battery storage can fall in price by a factor of two compared to the current lowest achievable price for ~14hour storage (lowest cost is currently achieved by using lead acid, but Na-S and MnO2-Zn are at or close to market and there is little reason to suppose that such a price drop cannot be achieved - and personally I doubt lithium ion will ever be truly competitive with these technologies for 14hour storage), then it looks very unlikely to me that space solar power could ever be competitive with stratospheric solar.
 I assumed that launch costs were zero, that transmit efficiency was 75% using solid state modules at 20c/W (the efficiency is slightly higher than can currently be achieved with COTS solid state microwave amplifiers, and the cost is about 65% that of the current cheapest solid state microwave amplifiers),and that collection efficiency was 90%. Even with no launch costs, this still ends up being quite expensive, especially as three satellites are required, negating the advantage of 24 hour sunlight. LCOE using the same model I used to cost stratospheric power was $30/Mwhr.
 Stratospheric solar power was just under $30/Mwhr assuming the battery cost reductions, i.e. even with free launch space solar was uncompetitive!
However, if there is a second ground station at 180 degree longitude difference, then as the rectenna station is a very low fraction of total cost, the LCOE almost halves to $16.5/Mwhr.
Even if spacex starship can achieve the really low launch costs claimed, then it would only just be possible for a dual ground station to be competitive with stratospheric solar + battery.
However, if there are further large reductions in the cost of solar cells, and solid state power amplifiers also reduce in cost dramatically (e.g. by widespread adoption in microwave ovens, which doesn't seem to be happening so far...), then space solar combined with cheap launch via spacex starship might start to make sense. In that case the cost of the stratospheric solar option would be dominated by the battery storage (and nobody seems to be predicting order of magnitude cost reductions in batteries), so the fact that space solar avoids batteries at the expense of spacelaunch (with could fall in price dramatically due to starship), and microwave links (which could fall in price dramatically due to ovens) means that space solar might have the potential to achieve really low energy costs in future.
 Personally I'd bet on stratospheric solar + batteries rather than space solar, but then again I have a vested interest in stratospheric solar as I'm applying for patents on the tether design.
Title: Re: Solar Power Satellites
Post by: MKrob89 on 11/16/2019 01:32 am
Hmm on second thoughts maybe I was too hard on space solar power - with the station in a Molniya orbit it can consist of a simple disc that spins to maintain alignment with the sun and maintain structural integrity without large scale structural supports. It is also possible to use thin film fresnel lenses to concentrate the sun onto smaller cells, reducing mass and increasing efficiency. A magnotorque method could be used to precess the station as the earth orbits around the sun.
If starlink can put 35T into a molniya orbit (not sure about this one tbh), and costs $10M to launch, then total LCOE for a three satellite, single ground station could drop as low as $21/Mwhr, beating stratospheric solar + battery storage.
A dual ground station might drop this to $11/Mwhr.
Another interesting thought is >2 ground stations geographically distributed with >3 satellites - what sort of power switching arrangements become possible?
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/16/2019 09:54 pm
Photonic Propulsion.
In this case solar sail spacecraft propelled by large laser.

https://www.google.com/url?sa=t&amp;source=web&amp;rct=j&amp;url=https://www.nasa.gov/sites/default/files/atoms/files/roadmap_to_interstellar_flight_tagged.pdf&amp;ved=2ahUKEwimrrGOyu_lAhVTJHIKHSi5CKcQFjACegQIARAB&amp;usg=AOvVaw0BSaFSxjTSGr9JPQqxDPka

These are Interstellar Probe people that want to send gram size probes to other stars using 70GW lasers. This is directly related to space based solar power as lasers can be multipurpose, provide propulsion for space craft and also beam power to lunar and Mars bases or earth.

There is huge amount info in this paper, here is brief summary of things that interest me. The simplist spacecraft will have large reflector or sail that laser directs beam onto, this is what paper uses for their case studies. More efficient but complicated version is call photon recycler (page 8) which uses concave reflector on spacecraft and larger one on laser, photons will bounce between the two making it lot more efficient. A paper I read on this said a factor of 5 is realistic with more possible, which means ×5 increase in thrust from same laser on flat reflector.

The laser is call laser phase array and is built up of lots small lasers eg 1kw, which can be added piecemeal along with solar arrays to provide power. Possible to start small and grow with demand. My interest is in cislunar transport which where based my examples. A laser array at EML1 could be used to send spacecraft from LLO to LEO, in theory it could slow them down at earth end but would require laser to work over 384,0000kms, better to use earth orbit (GEO) laser array to do this. GEO array would be used for LEO-LLO trip, with EML1 used to capture spacecraft into LLO.
To escape from orbit laser would give spacecraft boost every pass, slowly raising its orbit. In case of higher power systems would do it direct in few minutes without multiple orbits required, we are talk Gs of thrust here.


Here is an example from page47, using 70GW laser.
In case of
100kg – significant robotic mission with multi mission capability with 270m reflector.
Time to when laser diffraction spot equals reflector size= 1.06x105
s
Distance when laser diffraction spot equals reflector size=1.27x1012
m
Speed when laser diffraction spot equals reflector size=2.43x106m/s
Beta when laser diffraction spot equals reflector size=0.0081
Speed with continued illumination=3.46x106m/s
Beta with continued illumination=0.011
Acceleration when reflector is fully illuminated=0.237”g”

I calculated 0.12hrs (7min) of thrust to reach 1km/s, as distances increase thrust drops off so likely to be more than 7mins.  Time vs power is linear so 70MW laser would need 120hrs of thrust. Because of lower thrust it would need multiple orbits to build speed and now we are into higher DV flight profiles of SEPs. While thrust may be x1000 to orbital escape velocity,  time needed could be x5-10,000 ( uneducated guess) as no thrust is being provided for large part of orbit. While lasers may not be as effective at greater distances, should still be able to give enough thrust to provide course corrections for cislunar space craft. With Photon Recycler and their x5 gain in performance and that 120hrs for 70MW laser drops to 24hrs, may need to factor in slight heavier spacecraft reflector.

For lunar missions and beyond we really need to be using GW lasers but smaller 10MW lasers could be used with spacetugs for deploying smallsats in lower earth orbits, where DVs are in few 100m/s range. Large lasers can reduce travel time from LEO to LLO from 3-4days down to hours as spacecraft can be accelerated to well beyond 10km/s, just need large laser at other end to remove that extra DV.

Besides power beaming to surface assets lasers can also  be used for orbital debris cleanup, deflecting asteriods and communications. With high power lasers Gbs datarate between earth and Mars is possible.

Edit. With Cislunar transport GEO lasers have to do lot more work compared to EML1 laser. Roughly x3 extra DV for outbound and inbound lunar spacecraft. This is bonus as GEO lasers will have more work available moving spacecraft around earth orbits between moon missions.
These are expensive assets and need to be used 24/7 where possible.
 
Title: Re: Solar Power Satellites
Post by: edzieba on 11/17/2019 07:37 am
A less explored option is indirect solar propulsion. Fit out a craft with photovoltaic panels tuned as monochromatic receivers (demonstrated 70% efficiency, potentially 80% (https://ieeexplore.ieee.org/abstract/document/8547912)), and use your laser array to illuminate these cells rather than solar irradiation. This hybrid system allows for similar architectures to existing RTG and proposed reactor-based craft, but without these more massive on-board power sources, and without the low thrust issues of photon sail propulsion.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/17/2019 08:51 am
A less explored option is indirect solar propulsion. Fit out a craft with photovoltaic panels tuned as monochromatic receivers (demonstrated 70% efficiency, potentially 80% (https://ieeexplore.ieee.org/abstract/document/8547912)), and use your laser array to illuminate these cells rather than solar irradiation. This hybrid system allows for similar architectures to existing RTG and proposed reactor-based craft, but without these more massive on-board power sources, and without the low thrust issues of photon sail propulsion.
If you are talking about SEPs powered by laser instead of sun then yes there are benefits. One I read about would have ISP5000 while producing useful thrust ie measured in Ns not mNs.

This would allow MW lasers to drive larger craft, even if they are burning fuel.
Title: Re: Solar Power Satellites
Post by: CameronD on 11/18/2019 10:54 pm
Photonic Propulsion.
In this case solar sail spacecraft propelled by large laser.


These are Interstellar Probe people that want to send gram size probes to other stars using 70GW lasers. This is directly related to space based solar power as lasers can be multipurpose, provide propulsion for space craft and also beam power to lunar and Mars bases or earth.
........
The laser is call laser phase array and is built up of lots small lasers eg 1kw, which can be added piecemeal along with solar arrays to provide power. Possible to start small and grow with demand. ......
........
Besides power beaming to surface assets lasers can also  be used for orbital debris cleanup, deflecting asteriods and communications. With high power lasers Gbs datarate between earth and Mars is possible.
........

So you're saying it was mere Episode IV Rebel Alliance propaganda that called it a "Death Star" when really, all along, all the Empire were trying to build was an orbiting photonic propulsion/communication system for their interstellar probes?!???  ..and then those naughty Rebels had the audacity to go blow it up so now we'll never know if it worked or not (although it seemed to do a good job cleaning up planet-sized "orbital debris", so maybe they were indeed onto something!).

Someone should tell George Lucas he invented a whole movie series based on incorrect intel.  ;)

Title: Re: Solar Power Satellites
Post by: zubenelgenubi on 11/18/2019 11:47 pm
Photonic Propulsion.
In this case solar sail spacecraft propelled by large laser.


These are Interstellar Probe people that want to send gram size probes to other stars using 70GW lasers. This is directly related to space based solar power as lasers can be multipurpose, provide propulsion for space craft and also beam power to lunar and Mars bases or earth.
........
The laser is call laser phase array and is built up of lots small lasers eg 1kw, which can be added piecemeal along with solar arrays to provide power. Possible to start small and grow with demand. ......
........
Besides power beaming to surface assets lasers can also  be used for orbital debris cleanup, deflecting asteriods and communications. With high power lasers Gbs datarate between earth and Mars is possible.
........

Larry Niven, the Monks, and the Moties approve.  The Kzin do not.
Title: Moving the Electricity Grid to LEO
Post by: Enslaved_robot_boy on 12/09/2019 12:31 am
I read a lot about beaming microwave energy from space based solar arrays to earth ground stations. As the cost of solar continues to drop and satellite constellations like Starlink become more feasible, should we start thinking about beaming power from remote desert solar farms to other locations on the Earth's surface via LEO?

Is the whole idea too inefficient to contemplate?

The cost of grid maintenance is approximately 7cents/kWh. How cheap would solar and launch costs need to be to make this idea worth it?
Title: Re: Moving the Electricity Grid to LEO
Post by: Asteroza on 12/09/2019 06:58 am
I read a lot about beaming microwave energy from space based solar arrays to earth ground stations. As the cost of solar continues to drop and satellite constellations like Starlink become more feasible, should we start thinking about beaming power from remote desert solar farms to other locations on the Earth's surface via LEO?

Is the whole idea too inefficient to contemplate?

The cost of grid maintenance is approximately 7cents/kWh. How cheap would solar and launch costs need to be to make this idea worth it?

That's been proposed via a number of India-connected academics actually. Usually as part of a different relay arrangement, using lower SSO orbits riding the terminator line for the primary SPS, and equatorial-ish relay sats that can also do some relaying of terrestrial power. I believe Dr. Komerath at Georgia Tech was pushing for this and has published some materials regarding this. The combo of low orbits, higher frequencies, and interesting system arrangements has some merit.

https://www.researchgate.net/publication/261248228_Millimeterwave_Space_Power_Grid_architecture_development_2012 (https://www.researchgate.net/publication/261248228_Millimeterwave_Space_Power_Grid_architecture_development_2012)
Title: Re: Solar Power Satellites
Post by: Enslaved_robot_boy on 12/09/2019 07:25 am
Thanks so much for the link. Off to read more about it.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 04/03/2020 10:43 pm
Spaceshow podcast on space solar power.

https://www.thespaceshow.com/show/29-mar-2020/broadcast-3484-dr.-paul-jaffe

They initial market is military outposts as logistics of shipping generator fuel in war zone is difficult and very expensive eg Iraq convoys.

On concept he mentioned was stratosphere airships acting as relays. No details so my guess is use lasers to deliver power to airship from space as no clouds at these altitudes then microwave to ground. Shorter distances allows for more compact microwave equipment. Airship could stay in place for months, can be return to ground for storage or servicing. Easy to redeploy around world, just need to move ground receiver equipment.

Edit.
Laser to ground maybe affected by clouds, but with clear skies can deliver power at night so still has its uses. Lot depends on local climate, would work will in middle east. Still need diesel generators for backup but fuel requirements are greatly reduced.
Title: Re: Solar Power Satellites
Post by: Asteroza on 04/06/2020 12:51 am
Spaceshow podcast on space solar power.

https://www.thespaceshow.com/show/29-mar-2020/broadcast-3484-dr.-paul-jaffe

They initial market is military outposts as logistics of shipping generator fuel in war zone is difficult and very expensive eg Iraq convoys.

On concept he mentioned was stratosphere airships acting as relays. No details so my guess is use lasers to deliver power to airship from space as no clouds at these altitudes then microwave to ground. Shorter distances allows for more compact microwave equipment. Airship could stay in place for months, can be return to ground for storage or servicing. Easy to redeploy around world, just need to move ground receiver equipment.

Edit.
Laser to ground maybe affected by clouds, but with clear skies can deliver power at night so still has its uses. Lot depends on local climate, would work will in middle east. Still need diesel generators for backup but fuel requirements are greatly reduced.

Wasn't the SPS blimp relay company SolarEn? I know whomever it was scrubbed their web presence of the blimp/drigible work though. I think the original proposal used tethered flatpacks of tube blimps to give a wide horizontal surface area.
Title: Re: Solar Power Satellites
Post by: Vultur on 05/20/2020 03:54 pm
A press release from the US Naval Research Laboratory Monday on an experiment on the X-37 that intends to demonstrate converting solar power to microwaves:
https://www.navy.mil/submit/display.asp?story_id=112989
Title: Re: Solar Power Satellites
Post by: Paul451 on 05/21/2020 05:05 am
Not sure if it's been mentioned yet, but Geoffrey Landis and others have proposed "solar pumped lasers", where solar concentrators are used as the input energy for an otherwise conventional laser. Supposed efficiencies in the 30% range. If it can scale up (current Ukrainian experiments are in the MW range), this might be a way to improve the efficiency of tight-beamed solar power to PV panels as well as beam-propulsion.

In space, the solar-concentrator can be just reflective film. Cheap and light. So it doesn't matter if you get 30% efficiency at the laser and 30% at the receiving panel, if the first step is nearly free. The concentrator can also act as a solar sail and "hover" over a target site (rather than orbit), such as the lunar poles, or a remote military or mining base on Earth.

(A more fringe concept: "Stellasers", where you "hover" solar sails inside the sun's corona, where they act as end-reflectors for a multi-thousand [edit: million] km long laser that uses the solar medium as its lasing plasma.)
Title: Re: Solar Power Satellites
Post by: Asteroza on 05/21/2020 06:28 am
One classic issue is the simpler solar pumped laser designs feature a long parabolic trough design where the concentrated centerline is where your doped fiber will be. Unfortunately, for solar tracking purposes that would expect the trough long axis to point north/south so the trough mirror can rotate simply around the centerline fiber to follow the sun, and have fiber end cap beam directors with clear lines of sight. However, ideally you want a passive gravity gradient stabilized tower design, which would be orthogonal.
Title: Re: Solar Power Satellites
Post by: su27k on 07/10/2020 12:01 pm
Military spaceplane experiment sheds light on space solar satellites (https://spacenews.com/x-37b-experiment-sheds-light-on-space-solar-satellites/)

Quote
An experiment launched May 17 onboard the U.S. Air Force’s X-37B Orbital Test Vehicle-6 is based on over a decade of work focused on a modular space solar satellite capable of beaming energy to Earth.

Developed by the U.S. Naval Research Laboratory (NRL) in Washington, the hardware is called the Photovoltaic Radio-frequency Antenna Module, or PRAM for short.
Title: Re: Solar Power Satellites
Post by: Paul451 on 07/12/2020 02:31 am
One classic issue is the simpler solar pumped laser designs feature a long parabolic trough design where the concentrated centerline is where your doped fiber will be. [...] However, ideally you want a passive gravity gradient stabilized tower design, which would be orthogonal.

Most space-variants I've seen assume a parabolic or fresnel concentrating-reflector. That can include an angled reflection into the collector/fibre, making it more tower-like.

Additionally, while more obvious in a statite, any large reflector is in a powered pseudo-orbit and therefore will be acceleration-stabilised.
Title: Re: Solar Power Satellites
Post by: edzieba on 07/15/2020 10:58 am
Not sure if it's been mentioned yet, but Geoffrey Landis and others have proposed "solar pumped lasers", where solar concentrators are used as the input energy for an otherwise conventional laser. Supposed efficiencies in the 30% range. If it can scale up (current Ukrainian experiments are in the MW range), this might be a way to improve the efficiency of tight-beamed solar power to PV panels as well as beam-propulsion.

In space, the solar-concentrator can be just reflective film. Cheap and light. So it doesn't matter if you get 30% efficiency at the laser and 30% at the receiving panel, if the first step is nearly free. The concentrator can also act as a solar sail and "hover" over a target site (rather than orbit), such as the lunar poles, or a remote military or mining base on Earth.

(A more fringe concept: "Stellasers", where you "hover" solar sails inside the sun's corona, where they act as end-reflectors for a multi-thousand [edit: million] km long laser that uses the solar medium as its lasing plasma.)
E.E. 'Doc' Smith would be proud!
Title: Re: Solar Power Satellites
Post by: marshalb on 07/24/2020 02:22 pm
Great analytics and advice, thank you for the truthful inside look!!!
Title: Re: Solar Power Satellites
Post by: Robotbeat on 07/24/2020 05:37 pm
Efficiency still matters in terms of thermal management.
Title: Re: Solar Power Satellites
Post by: RedLineTrain on 03/21/2021 11:02 pm
Interestingly, nowadays you don't even have to transmit energy from the solar power satellite.  Rather, you can consume it on-satellite to do your scam mining.

For a host of reasons, I still don't think solar power satellites makes sense.  But the efficiency equation looks a lot better in this light.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 03/22/2021 01:14 am
Interestingly, nowadays you don't even have to transmit energy from the solar power satellite.  Rather, you can consume it on-satellite to do your scam mining.

For a host of reasons, I still don't think solar power satellites makes sense.  But the efficiency equation looks a lot better in this light.
As Robotbeat stated still need to deal with generation of all that heat. If satellite consumes kw of power doing data process, most of that power will end up as heat.

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Title: Re: Solar Power Satellites
Post by: RedLineTrain on 03/22/2021 02:19 pm
Interestingly, nowadays you don't even have to transmit energy from the solar power satellite.  Rather, you can consume it on-satellite to do your scam mining.

For a host of reasons, I still don't think solar power satellites makes sense.  But the efficiency equation looks a lot better in this light.
As Robotbeat stated still need to deal with generation of all that heat. If satellite consumes kw of power doing data process, most of that power will end up as heat.

Yes, agreed.  For that and other reasons, it doesn't seem to make sense.  However, it's interesting to see others' napkin math on how close it is to making sense.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 03/22/2021 03:33 pm
Rejecting heat isn’t necessarily that expensive if you have really cheap launch.
Title: Re: Solar Power Satellites
Post by: john_bucknell on 04/07/2021 01:12 am
https://www.nextbigfuture.com/2021/04/caltech-space-based-solar-power-cubesat-demo-flying-december-2021.html
Title: Re: Solar Power Satellites
Post by: su27k on 04/11/2021 03:24 am
https://forum.nasaspaceflight.com/index.php?topic=52037.msg2218621#msg2218621

Quote from: Robotbeat
This part is interesting. I suppose, since this is in the "space tech" portion, this means either space based solar power or perhaps some cooperation of solar/fission/fusion/batteries/fuelcells with terrestrial versions.

Quote
NASA’s space technology program, which received $1.1 billion in 2021, would get $1.4 billion in 2022, a 27% increase. That funding “would enhance the capabilities and reduce the costs of the full range of NASA missions and provide new technologies to help the commercial space industry grow,” the budget document states. That includes support for what the White House called “novel early-stage space technology research that would support the development of clean energy.”

(In the 1970s, there was some NASA Aeronautics research that went toward wind energy research, but this is space tech, so my guess is space-based solar power.)

This is an interesting hypothesis. This reminds me there's a frequent caller into TheSpaceShow who said he was working with the unions to get Biden administration paying more attention on Space Solar Power (apparently the unions think this will give SLS a purpose, which of course makes little sense, but hey it's politics), and he said recently there has been some progress on this although he couldn't talk about it. So this could be a possibility.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/11/2021 04:52 am
https://forum.nasaspaceflight.com/index.php?topic=52037.msg2218621#msg2218621

Quote from: Robotbeat
This part is interesting. I suppose, since this is in the "space tech" portion, this means either space based solar power or perhaps some cooperation of solar/fission/fusion/batteries/fuelcells with terrestrial versions.

Quote
NASA’s space technology program, which received $1.1 billion in 2021, would get $1.4 billion in 2022, a 27% increase. That funding “would enhance the capabilities and reduce the costs of the full range of NASA missions and provide new technologies to help the commercial space industry grow,” the budget document states. That includes support for what the White House called “novel early-stage space technology research that would support the development of clean energy.”

(In the 1970s, there was some NASA Aeronautics research that went toward wind energy research, but this is space tech, so my guess is space-based solar power.)

This is an interesting hypothesis. This reminds me there's a frequent caller into TheSpaceShow who said he was working with the unions to get Biden administration paying more attention on Space Solar Power (apparently the unions think this will give SLS a purpose, which of course makes little sense, but hey it's politics), and he said recently there has been some progress on this although he couldn't talk about it. So this could be a possibility.
A little ironically, Starship is the only thing on the drawing board (unless Blue has something they're not showing us) that has a prayer of making SBSP feasible.

If you don't mind, I'm going to repost your post in the Space Policy thread, as it is relevant to Biden Administration internal negotiations.
Title: Re: Solar Power Satellites
Post by: su27k on 04/11/2021 05:44 am
A little ironically, Starship is the only thing on the drawing board (unless Blue has something they're not showing us) that has a prayer of making SBSP feasible.

Makes sense given Starship is basically the half sized version of Boeing's Space Freighter (http://www.aerospaceprojectsreview.com/blog/?p=86) which was specifically designed to support NASA's 1978 Solar Power Satellite study.

Quote
If you don't mind, I'm going to repost your post in the Space Policy thread, as it is relevant to Biden Administration internal negotiations.

No problem, I would have posted in that thread except I couldn't due to the L2 member restriction.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 04/11/2021 10:58 am
The initial market for SBSP is forward military bases where power can costs dollars a kwhr and can cost lives trucking fuel due to terrorist attacks.
Caltech idea is to fly satellites in MEO which means they will be quite a few in orbit to support single base. When not supplying power to that base they can be supplying other military bases else where in world.
While domestic bases buy power from grid and commercial rates they also spend lot of money backup generators. SBSP could provide that backup generation.



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Title: Re: Solar Power Satellites
Post by: kfsorensen on 04/12/2021 12:15 am
Space solar power satellites in GEO would be nearly useless for forward-operating military bases since the rectenna size would be enormous, on the order of ten kilometers in diameter.  That's not any sort of thing that a FOB will be toting around.
Title: Re: Solar Power Satellites
Post by: Alberto-Girardi on 04/12/2021 04:49 pm
Space solar power satellites in GEO would be nearly useless for forward-operating military bases since the rectenna size would be enormous, on the order of ten kilometers in diameter.  That's not any sort of thing that a FOB will be toting around.

Great point, maybe the use by military base is unfavorable for the development of this technology because many things will be secretated.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 04/12/2021 05:14 pm


Space solar power satellites in GEO would be nearly useless for forward-operating military bases since the rectenna size would be enormous, on the order of ten kilometers in diameter.  That's not any sort of thing that a FOB will be toting around.

Great point, maybe the use by military base is unfavorable for the development of this technology because many things will be secrateted.

Caltech are targetting MEO which is lot lower requiring smaller rectanna. How big they don't say.  Military base would need MWs of power.

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Title: Re: Solar Power Satellites
Post by: Paul451 on 04/12/2021 06:53 pm
[...]
Space solar power satellites in GEO would be nearly useless for forward-operating military bases since the rectenna size would be enormous, on the order of ten kilometers in diameter.  That's not any sort of thing that a FOB will be toting around.
[...]
Caltech are targetting MEO which is lot lower requiring smaller rectanna.

Altitude of MEO is generally a sixth of GEO up to a third of GEO. So the diameter of the rectenna will be a third to a sixth of Kurt's figure. Multiple kilometres for each of his tens of kilometres. Still unreasonable for a FOB.

[edit: Kept changing the numbers. Blurg.]
Title: Re: Solar Power Satellites
Post by: Darkseraph on 04/12/2021 07:43 pm
Is it a given that a military base has to build a singular gigantic 10 km rectenna to collect every drop of energy with maximum efficiency as you would want in a commercial system? The main reasoning I've seen for using this technology militarily is that energy and fuel costs for forward operating bases, especially in war zones is enormous compared to the average cost consumers pay. And transporting that energy can cost many lives.

Perhaps such a system could sacrifice maximum efficiency in collecting power in order to gain operational flexibility, security and  overall lower costs in terms of human lives and resources? For example, you could use an electromagnetic wavelength that results in a smaller rectenna, but has poorer conversion efficiencies. Or just use a fractional arrays of modular rectennas and don't collect all the power within the 10km radius, just enough of it.

This would have to be weighed against other options for this problem such as keep doing what they're already doing despite drawbacks, using large solar arrays to charge large amounts of batteries at a base or even using small modular nuclear reactors ( Although I think that would be much less likely than even space solar because of public opposition and the risk of massive land-based nuclear disaster during warfare pushing the cost of just defending the reactor through the stratosphere.)

Title: Re: Solar Power Satellites
Post by: kfsorensen on 04/13/2021 12:28 am
Yes, it is a given.  The absorption characteristics of the Earth's atmosphere dictate the transmission frequency (2.45 GHz), and given the distance of 36,000 km (GEO) and even with the assumption of 1000-m transmitter diameter (nearly the size of a Star Destroyer), your ground rectenna is 10 km in diameter.  It makes no difference whether you're transmitting a watt or a gigawatt.  The equation is independent of power level.

diameter_receiver = 2.44*(36,000,000 m)*(300,000,000 m/s)/((1000m)*(2,450,000,000/s)) = 10 km
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 04/13/2021 12:53 am
Yes, it is a given.  The absorption characteristics of the Earth's atmosphere dictate the transmission frequency (2.45 GHz), and given the distance of 36,000 km (GEO) and even with the assumption of 1000-m transmitter diameter (nearly the size of a Star Destroyer), your ground rectenna is 10 km in diameter.  It makes no difference whether you're transmitting a watt or a gigawatt.  The equation is independent of power level.

diameter_receiver = 2.44*(36,000,000 m)*(300,000,000 m/s)/((1000m)*(2,450,000,000/s)) = 10 km
At 18000km MEO its 5km but can use smaller rectanna and accept less power absorption.

The advantage of MEO is satellites can deliver power to multiple sites around planet each orbit.

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Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/13/2021 01:00 am
Yes, it is a given.  The absorption characteristics of the Earth's atmosphere dictate the transmission frequency (2.45 GHz), and given the distance of 36,000 km (GEO) and even with the assumption of 1000-m transmitter diameter (nearly the size of a Star Destroyer), your ground rectenna is 10 km in diameter.  It makes no difference whether you're transmitting a watt or a gigawatt.  The equation is independent of power level.

diameter_receiver = 2.44*(36,000,000 m)*(300,000,000 m/s)/((1000m)*(2,450,000,000/s)) = 10 km
There's some leeway in picking the transmission frequency. 10GHz is probably acceptable. But besides atmospheric absorption and weather, higher frequency electronics also tend to be lower efficiency and more expensive.
Title: Re: Solar Power Satellites
Post by: Vultur on 04/13/2021 01:11 am
What does limit the wavelengths/frequencies you use? Is it clouds and such?
Title: Re: Solar Power Satellites
Post by: Paul451 on 04/13/2021 01:29 am
What does limit the wavelengths/frequencies you use? Is it clouds and such?

Also licencing. For example, 10GHz is allocated to amateur radio and satellite use.
Title: Re: Solar Power Satellites
Post by: Paul451 on 04/13/2021 01:36 am
At 18000km MEO its 5km but can use smaller rectanna and accept less power absorption.

Yeah, but receiver area drops with the square. A 1km diameter rectenna array will only receive 4% of power of a 5km one.
Title: Re: Solar Power Satellites
Post by: Zed_Noir on 04/13/2021 03:36 am
Yes, it is a given.  The absorption characteristics of the Earth's atmosphere dictate the transmission frequency (2.45 GHz), and given the distance of 36,000 km (GEO) and even with the assumption of 1000-m transmitter diameter (nearly the size of a Star Destroyer), your ground rectenna is 10 km in diameter.  It makes no difference whether you're transmitting a watt or a gigawatt.  The equation is independent of power level.

diameter_receiver = 2.44*(36,000,000 m)*(300,000,000 m/s)/((1000m)*(2,450,000,000/s)) = 10 km

What if you set up orbital transmission rebroadcasting stations in high LEO like about 850 km altitude?
Title: Re: Solar Power Satellites
Post by: ncb1397 on 04/13/2021 04:37 am
SBSP could benefit significantly from lunar materials for the trusses, photovoltaic materials, etc. You would probably want a man tended space station in the same orbital plane as the SBSP constellation to perform maintenance or construction. All this isn't too outlandish and isn't out of step with what has already been done on the ISS and is in line with Artemis.

https://www.youtube.com/watch?v=mDIDlEJUdlo

It should be a DOE/NASA/EPA (maybe even DOD) joint project if that is really what they are aiming for. Of course, building a bunch of directed energy satellites in Earth orbit is going to have its own share of political issues.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/13/2021 05:00 am
You might be able to use lunar material for propellant to move the satellite from LEO to a higher orbit and maybe water for the heat rejection system. I doubt anything else would be worth while from the Moon vs just launching it from Earth.
Title: Re: Solar Power Satellites
Post by: Proponent on 04/13/2021 01:26 pm
For large-scale civilian purposes, microwave transmission is usually preferred over laser transmission.  For temporary use in remote locations, such as forward bases, perhaps laser transmission becomes relatively more attractive.  For one thing, the  limit on the beam's power density might be higher.  If the location does not have a great deal of cloud cover and some outages are tolerable, I would think a laser-based system would trade well given that minimum receiver size is no longer set by optics but by beam power density.
Title: Re: Solar Power Satellites
Post by: Jim on 04/13/2021 02:38 pm
SBSP could benefit significantly from lunar materials for the trusses, photovoltaic materials, etc. You would probably want a man tended space station in the same orbital plane as the SBSP constellation to perform maintenance or construction. All this isn't too outlandish and isn't out of step with what has already been done on the ISS and is in line with Artemis.

https://www.youtube.com/watch?v=mDIDlEJUdlo

It should be a DOE/NASA/EPA (maybe even DOD) joint project if that is really what they are aiming for. Of course, building a bunch of directed energy satellites in Earth orbit is going to have its own share of political issues.

NASA has no role in it
Title: Re: Solar Power Satellites
Post by: ncb1397 on 04/13/2021 02:53 pm
SBSP could benefit significantly from lunar materials for the trusses, photovoltaic materials, etc. You would probably want a man tended space station in the same orbital plane as the SBSP constellation to perform maintenance or construction. All this isn't too outlandish and isn't out of step with what has already been done on the ISS and is in line with Artemis.

https://www.youtube.com/watch?v=mDIDlEJUdlo

It should be a DOE/NASA/EPA (maybe even DOD) joint project if that is really what they are aiming for. Of course, building a bunch of directed energy satellites in Earth orbit is going to have its own share of political issues.

NASA has no role in it

As in, a more hands off approach? Because technology development projects like Archinaut are funded through NASA..which could indirectly help field SBSP. And then you have the freeflyer solicitation that may be linked to the man-tended facility. And they are the only organization really planning for lunar surface access, will have personnel on the moon, etc. Mapping of lunar resources is also done by LRO, they will have a 50 kilowatt space station in lunar orbit for power beaming experiments (which could solve some of the lunar surface power problems). Delivery of the first lunar derived aluminum for in space 3d printing experiments could also be done via HLS on gateway. That metal would already be by product of oxygen generation experiments planned by ESA/NASA.

Quote
But passing a current through it causes the oxygen to be extracted from the regolith and migrate across the salt to be collected at an anode. As a bonus this process also converts the regolith into usable metal alloys.
https://www.esa.int/Enabling_Support/Space_Engineering_Technology/ESA_opens_oxygen_plant_making_air_out_of_moondust

You could also have made the case that NASA would have no role in hollywood movie production or cosmetic advertising. Yet, here we are. The logic goes that they are already doing 99% of what is required to aid in one project or another, so there really isn't much reason not to and is superior to making Tom Cruise build a space station in LEO to film his movie.
Title: Re: Solar Power Satellites
Post by: Jim on 04/13/2021 03:05 pm

As in, a more hands off approach? Because technology development projects like Archinaut are funded through NASA..which could indirectly help field SBSP. And then you have the freeflyer solicitation that may be linked to the man-tended facility. And they are the only organization really planning for lunar surface access, will have personnel on the moon, etc. Mapping of lunar resources is also done by LRO, they will have a 50 kilowatt space station in lunar orbit for power beaming experiments (which could solve some of the lunar surface power problems). Delivery of the first lunar derived aluminum for in space 3d printing experiments could also be done via HLS on gateway. That metal would already be by product of oxygen generation experiments planned by ESA/NASA.


NASA is exploration and research.  Not exploitation, that is up the marketplace and industry.  there is no need or reason for NASA to be involved with SBSP.
Title: Re: Solar Power Satellites
Post by: Jim on 04/13/2021 03:06 pm

You could also have made the case that NASA would have no role in hollywood movie production or cosmetic advertising. Yet, here we are.

NASA doesn't
Title: Re: Solar Power Satellites
Post by: ncb1397 on 04/13/2021 03:09 pm

You could also have made the case that NASA would have no role in hollywood movie production or cosmetic advertising. Yet, here we are.

NASA doesn't

....

Quote
One of the biggest films to be announced in 2020 was Tom Cruise and Doug Liman’s $200 million space movie that will become the first Hollywood narrative feature to film scenes in space. The project will also make Cruise the first actor to travel to the International Space Station (ISS) to film a movie
https://www.indiewire.com/2020/12/russia-battles-tom-cruise-sending-actor-space-1234606110/

Quote
But now, NASA, one of the space station's primary operators, is preparing to oversee the largest push of business activity aboard the ISS. Later this month, up to 10 bottles of a new Estée Lauder (EL) skincare serum will launch to the space station, a NASA spokesperson told CNN Business. NASA astronauts are expected to film the items in the microgravity environment of the ISS and the company will be able to use that footage in ad campaigns or other promotional material.
https://www.cnn.com/2020/09/17/tech/estee-lauder-iss-nasa-advertisement-scn/index.html

There are a few energy production projects that industry is probably unwilling to risk. Fusion is probably one of them - hence ITER (yes, it is a "research" reactor). SBSP is another one.

edit: Just ran across this that I was unaware of...

Quote
In addition to its usual suite of secret military tech, the X-37B will also host a few unclassified experiments during its upcoming sojourn in space. NASA is sending up two experiments to study the effects of radiation on seeds, and the US Air Force Academy is using the space plane to deploy a small research satellite. But the real star of the show is a small solar panel developed by the physicists at the Naval Research Lab that will be used to conduct the first orbital experiment with space-based solar power.

“This is a major step forward,” says Paul Jaffe, an electronics engineer at the Naval Research Lab and lead researcher on the project. “This is the first time that any component geared towards a solar-powered satellite system has ever been tested in orbit.”
https://www.wired.com/story/a-secret-space-plane-is-carrying-a-solar-experiment-to-orbit/

A NASA space plane project transferred to the DOD is aiding a solar power satellite experiment in low earth orbit. Funny how things work out.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 04/13/2021 04:21 pm
Looks like NGIS has been funding Caltech project from AFRL money. Military interest is in supplying their FOBs.

https://www.robins.af.mil/News/Article-Display/Article/1998062/us-air-force-research-laboratory-developing-space-solar-power-beaming/

AFRL researchers are focused on developing and demonstrating some of the key technologies necessary to integrate into a conceptual space-based power beaming system. Northrop Grumman will partner with AFRL and has been awarded a contract valued at more than $100 million to develop and deliver the critical hardware elements to support space-based experiments into this leading-edge technology.


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Title: Re: Solar Power Satellites
Post by: Jim on 04/13/2021 04:31 pm

You could also have made the case that NASA would have no role in hollywood movie production or cosmetic advertising. Yet, here we are. The logic goes that they are already doing 99% of what is required to aid in one project or another, so there really isn't much reason not to and is superior to making Tom Cruise build a space station in LEO to film his movie.

NASA isn't doing any cosmetic advertising.  What  Estée Lauder does with the videos is up to them.

NASA isn't funding Cruise or promoting it.

Both are NASA supporting industry and not doing the work itself.
Title: Re: Solar Power Satellites
Post by: Jim on 04/13/2021 04:34 pm

A NASA space plane project transferred to the DOD is aiding a solar power satellite experiment in low earth orbit. Funny how things work out.

It was transferred before they were built.  So, nothing really funny. 
Title: Re: Solar Power Satellites
Post by: ncb1397 on 04/13/2021 04:45 pm

A NASA space plane project transferred to the DOD is aiding a solar power satellite experiment in low earth orbit. Funny how things work out.

It was transferred before they were built.  So, nothing really funny.

It was transferred to Darpa in September 2004. They were doing atmospheric captive carry tests in June 2005. First glide flight was ~18 months after the transfer. That development/build was suspiciously quick.

Consider a similar X plane project. X-61A was awarded in April 2016 and had its first captive carry flight in November 2019. That project took on the order of 3.5 years to captive carry rather then .75 years.
Title: Re: Solar Power Satellites
Post by: Jim on 04/13/2021 05:31 pm

It was transferred to Darpa in September 2004. They were doing atmospheric captive carry tests in June 2005. First glide flight was ~18 months after the transfer. That development/build was suspiciously quick.


I had first hand knowledge, I was working launch vehicle integration for it.  The drop test vehicles were not the same as the orbital ones and had ballast for orbital systems.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/13/2021 05:52 pm

As in, a more hands off approach? Because technology development projects like Archinaut are funded through NASA..which could indirectly help field SBSP. And then you have the freeflyer solicitation that may be linked to the man-tended facility. And they are the only organization really planning for lunar surface access, will have personnel on the moon, etc. Mapping of lunar resources is also done by LRO, they will have a 50 kilowatt space station in lunar orbit for power beaming experiments (which could solve some of the lunar surface power problems). Delivery of the first lunar derived aluminum for in space 3d printing experiments could also be done via HLS on gateway. That metal would already be by product of oxygen generation experiments planned by ESA/NASA.


NASA is exploration and research.  Not exploitation, that is up the marketplace and industry.  there is no need or reason for NASA to be involved with SBSP.
NASA absolutely does fund Archinaut, similar efforts, and encourage industry.


...
Both are NASA supporting industry and not doing the work itself.
Agreed with that.

And there are a lot of reasons you wouldn't want NASA to do the work of SBSP (i.e. actually delivering useful power to consumers) beyond tech demo type stuff. NASA has a huge amount of overhead and uses contractors for everything it can. And has weird procurement requirements that make everything slow and expensive.

And some of this isn't just the fault of the bureaucracy but of Congress telling NASA they cannot compete with private industry if private industry can do it better. And this is probably for the best.
Title: Re: Solar Power Satellites
Post by: Vultur on 04/13/2021 10:52 pm
For large-scale civilian purposes, microwave transmission is usually preferred over laser transmission.  For temporary use in remote locations, such as forward bases, perhaps laser transmission becomes relatively more attractive.  For one thing, the  limit on the beam's power density might be higher.  If the location does not have a great deal of cloud cover and some outages are tolerable, I would think a laser-based system would trade well given that minimum receiver size is no longer set by optics but by beam power density.

Yeah, I wonder. I think electricity -> laser -> electricity would be significantly less efficient, but if you could get away with a small receiver, it might be worth it anyway?

And that application might not care about whether the beam is dangerous to fly through (presumably the military base would be a no-fly zone anyway, and their own people would know where the beam was).
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 04/14/2021 12:56 am
For large-scale civilian purposes, microwave transmission is usually preferred over laser transmission.  For temporary use in remote locations, such as forward bases, perhaps laser transmission becomes relatively more attractive.  For one thing, the  limit on the beam's power density might be higher.  If the location does not have a great deal of cloud cover and some outages are tolerable, I would think a laser-based system would trade well given that minimum receiver size is no longer set by optics but by beam power density.

Yeah, I wonder. I think electricity -&gt; laser -&gt; electricity would be significantly less efficient, but if you could get away with a small receiver, it might be worth it anyway?

And that application might not care about whether the beam is dangerous to fly through (presumably the military base would be a no-fly zone anyway, and their own people would know where the beam was).
Laser is better suited to moon where smaller solar arrays are cheaper to deploy on surface. If lunar base becomes large enough then microwaves higher efficiency is better solution.

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Title: Re: Solar Power Satellites
Post by: edzieba on 04/14/2021 09:45 am
If you want to avoid microwaves, then the 10um window is the next best option for minimising atmospheric losses. Fortunately, that works well with commercially available high power CO2 lasers. Unfortunately, those lasers are not particularly efficient, so what you gain in lowering atmospheric losses you lose in energy conversion losses.
Title: Re: Solar Power Satellites
Post by: su27k on 07/27/2021 05:18 am
Op-ed | It’s time to seriously consider space-based solar power (https://spacenews.com/op-ed-its-time-to-seriously-consider-space-based-solar-power/)

Quote
In the late 1960s, enterprising scientist Peter Glaser proposed using orbiting satellites to collect incoming solar radiation, transform it into microwaves, and beam it down to focused receivers on Earth where it would be converted into electricity.

Although space-based solar power (SBSP) sounds like science fiction, scientists and engineers have explored developing the futuristic technology for decades but repeatedly came to the same conclusion: SBSP is likely technologically possible but for it to be feasible, launch costs will have to come down considerably. Now that companies like SpaceX, Blue Origin, and Rocket Lab have demonstrated re-use capabilities and launch costs are plummeting, it is time to think seriously and boldly about the development of SBSP.
Title: Re: Solar Power Satellites
Post by: su27k on 07/28/2021 03:15 pm
John Bucknell, the former SpaceX engineer who proposed a nuclear SSTO, started a Space Solar Power company: Virtus Solis Technologies (https://www.virtussolis.space/), he was on the spaceshow recently to promote this: https://thespaceshow.com/show/02-jul-2021/broadcast-3716-john-bucknell

The idea seems to be molniya orbit constellation, but not much details is offered. I get the impression it's like Starlink in terms of mass production of relatively small satellites, but for solar power.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 07/28/2021 05:45 pm
John Bucknell, the former SpaceX engineer who proposed a nuclear SSTO, started a Space Solar Power company: Virtus Solis Technologies (https://www.virtussolis.space/), he was on the spaceshow recently to promote this: https://thespaceshow.com/show/02-jul-2021/broadcast-3716-john-bucknell

The idea seems to be molniya orbit constellation, but not much details is offered. I get the impression it's like Starlink in terms of mass production of relatively small satellites, but for solar power.
Haven't listen to show but did read webpage. They are using LEO satellite constellation and microwave beaming. Customer ground stations are likely to be large and expensive, but lot smaller than ones for GEO sats which are 100metres across.

Had price of 25c unit which could be competitive in remote locations but not in urban areas.

My guess is first customers will be miltary forward bases and remote mines as these customers will pay >$1unit.

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Title: Re: Solar Power Satellites
Post by: Robotbeat on 07/28/2021 06:55 pm
The unit is kWh, by the way. 1000 Watts for 1 hour.

25¢/kWh isn’t THAT bad. On par with residential electricity prices in California, parts of the Northeast, and Hawaii and any place reliant on diesel generator power. German residential electricity prices are about 37¢/kWh.

I still think there’s a case to be made for much larger arrays, higher orbits, and lower frequencies. Conversion efficiencies improve at lower frequencies and cost per watt for the power electronics is also lower at lower frequencies. The better efficiency also means lower rejection costs. Really, you would want multiple Gigawatts per receiving station and you should be able to have more like 5¢/kWh, competitive across the board.

But I realize this is a pretty big first step so it probably makes sense to start smaller even if the costs are so much higher.

Overall, I do think that space-based solar power is a lot more realistic for grid power generation than nuclear fusion.
Title: Re: Solar Power Satellites
Post by: Paul451 on 07/29/2021 10:02 am
On par with residential electricity prices in California, parts of the Northeast, and Hawaii and any place reliant on diesel generator power. German residential electricity prices are

You aren't putting receivers on your home roof. You have to compare with wholesale prices.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 07/29/2021 12:17 pm
On par with residential electricity prices in California, parts of the Northeast, and Hawaii and any place reliant on diesel generator power. German residential electricity prices are

You aren't putting receivers on your home roof. You have to compare with wholesale prices.
yup
Title: Re: Solar Power Satellites
Post by: Vultur on 07/29/2021 03:24 pm
The idea seems to be molniya orbit constellation, but not much details is offered. I get the impression it's like Starlink in terms of mass production of relatively small satellites, but for solar power.

Huh. That is super cool.

My big question is how much starting capital it will take to start producing power.
Title: Re: Solar Power Satellites
Post by: su27k on 08/04/2021 05:30 am
Caltech Announces Breakthrough $100 Million Gift to Fund Space-based Solar Power Project (https://www.caltech.edu/about/news/caltech-announces-breakthrough-100-million-gift-to-fund-space-based-solar-power-project)

Quote from: Caltech
Today, Caltech is announcing that Donald Bren, chairman of Irvine Company and a lifetime member of the Caltech Board of Trustees, donated over $100 million to form the Space-based Solar Power Project (SSPP), which is developing technology capable of generating solar power in space and beaming it back to Earth.

The donation was made anonymously in 2013, but the gift is now being disclosed as SSPP nears a significant milestone: a test launch of multifunctional technology-demonstrator prototypes that collect sunlight and convert it to electrical energy, transfer energy wirelessly in free-space using radio frequency (RF) electrical power, and deploy ultralight structures that will be used to integrate them.

Donald Bren first learned about the potential for space-based solar energy manufacturing in an article in the magazine Popular Science and in 2011, he approached Caltech's then-president Jean-Lou Chameau to discuss the creation of a space-based solar power research project. In 2013, he and his wife, Brigitte, a Caltech trustee, agreed to make the donation to fund the project. The first of the donations that now exceed $100 million was made that year through the Donald Bren Foundation, and the research began.

"Donald Bren has brought the same drive and discipline that he has demonstrated with master planning communities to the Space Solar Program," says Caltech President Thomas F. Rosenbaum. "He has presented a remarkable technical challenge that promises a remarkable payoff for humanity: a world powered by uninterruptible renewable energy."

Donald Bren is best known for master planning and master building the all-new City of Irvine, regularly named one of America's greenest cities. He has led Irvine Company's effort to permanently preserve more than 60 percent (57,500 acres) of the Irvine Ranch property along the California coast.

"I have been a student researching the possible applications of space-based solar energy for many years," says Donald Bren. "My interest in supporting the world-class scientists at Caltech is driven by my belief in harnessing the natural power of the sun for the benefit of everyone."

SSPP aims to ultimately produce a global supply of affordable, renewable, clean energy. A key benefit of harnessing solar power from space is that it provides access to the sun to create power all day, every day, free from weather constraints or darkness of night.

The project's first test, which will occur in early 2023, will launch technology prototypes for the solar power generators and RF wireless power transfer, and includes a deployable structure measuring roughly 6 feet by 6 feet.

The Brens have no financial stake in the project and will not benefit financially from any technology that is created.

"It shows the magnitude of the generosity," says Ali Hajimiri, Caltech's Bren Professor of Electrical Engineering and Medical Engineering and co-director of SSPP. "They really want to change the world and truly see this as an opportunity to make a lasting difference for the planet, while generating a broad range of novel technologies with impact in many areas such as wireless power, communications, and sensing."

The Bren's gift has allowed researchers to overcome many early hurdles and funded the hiring of doctoral students to work on the project with a five-year commitment, notes Sergio Pellegrino, Caltech's Joyce and Kent Kresa Professor of Aerospace and Professor of Civil Engineering and co-director of SSPP. Pellegrino is also a senior research scientist at JPL, which Caltech manages for NASA.

"It allows us to think ahead," Pellegrino says. "Without that, it couldn't get done."

"Solar energy is the world's most abundant energy resource. However, sunlight is intermittent at the earth's surface. This ambitious project is a transformative approach to large-scale solar energy harvesting for the Earth that overcomes this intermittency and the need for energy storage, since sunlight shines continuously in space," says Harry A. Atwater, who is an SSPP researcher, Otis Booth Leadership Chair of the Division of Engineering and Applied Science and the Howard Hughes Professor of Applied Physics and Materials Science, and director of the Liquid Sunlight Alliance.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 08/04/2021 10:04 am
SBSP could benefit significantly from lunar materials for the trusses, photovoltaic materials, etc. You would probably want a man tended space station in the same orbital plane as the SBSP constellation to perform maintenance or construction. All this isn't too outlandish and isn't out of step with what has already been done on the ISS and is in line with Artemis.

...

It should be a DOE/NASA/EPA (maybe even DOD) joint project if that is really what they are aiming for. Of course, building a bunch of directed energy satellites in Earth orbit is going to have its own share of political issues.

NASA has no role in it
You could also have made the case that NASA would have no role in hollywood movie production or cosmetic advertising. Yet, here we are. The logic goes that they are already doing 99% of what is required to aid in one project or another, so there really isn't much reason not to and is superior to making Tom Cruise build a space station in LEO to film his movie.

NASA isn't doing any cosmetic advertising.  What  Estée Lauder does with the videos is up to them.

NASA isn't funding Cruise or promoting it.

Both are NASA supporting industry and not doing the work itself.

Sounds like NASA has a "role" then (supporting industry), vs "no role."  ???
Title: Re: Solar Power Satellites
Post by: davamanra on 08/04/2021 06:18 pm
Caltech Announces Breakthrough $100 Million Gift to Fund Space-based Solar Power Project (https://www.caltech.edu/about/news/caltech-announces-breakthrough-100-million-gift-to-fund-space-based-solar-power-project)

Quote from: Caltech
Today, Caltech is announcing that Donald Bren, chairman of Irvine Company and a lifetime member of the Caltech Board of Trustees, donated over $100 million to form the Space-based Solar Power Project (SSPP), which is developing technology capable of generating solar power in space and beaming it back to Earth.

The donation was made anonymously in 2013, but the gift is now being disclosed as SSPP nears a significant milestone: a test launch of multifunctional technology-demonstrator prototypes that collect sunlight and convert it to electrical energy, transfer energy wirelessly in free-space using radio frequency (RF) electrical power, and deploy ultralight structures that will be used to integrate them.

Donald Bren first learned about the potential for space-based solar energy manufacturing in an article in the magazine Popular Science and in 2011, he approached Caltech's then-president Jean-Lou Chameau to discuss the creation of a space-based solar power research project. In 2013, he and his wife, Brigitte, a Caltech trustee, agreed to make the donation to fund the project. The first of the donations that now exceed $100 million was made that year through the Donald Bren Foundation, and the research began.

"Donald Bren has brought the same drive and discipline that he has demonstrated with master planning communities to the Space Solar Program," says Caltech President Thomas F. Rosenbaum. "He has presented a remarkable technical challenge that promises a remarkable payoff for humanity: a world powered by uninterruptible renewable energy."

Donald Bren is best known for master planning and master building the all-new City of Irvine, regularly named one of America's greenest cities. He has led Irvine Company's effort to permanently preserve more than 60 percent (57,500 acres) of the Irvine Ranch property along the California coast.

"I have been a student researching the possible applications of space-based solar energy for many years," says Donald Bren. "My interest in supporting the world-class scientists at Caltech is driven by my belief in harnessing the natural power of the sun for the benefit of everyone."

SSPP aims to ultimately produce a global supply of affordable, renewable, clean energy. A key benefit of harnessing solar power from space is that it provides access to the sun to create power all day, every day, free from weather constraints or darkness of night.

The project's first test, which will occur in early 2023, will launch technology prototypes for the solar power generators and RF wireless power transfer, and includes a deployable structure measuring roughly 6 feet by 6 feet.

The Brens have no financial stake in the project and will not benefit financially from any technology that is created.

"It shows the magnitude of the generosity," says Ali Hajimiri, Caltech's Bren Professor of Electrical Engineering and Medical Engineering and co-director of SSPP. "They really want to change the world and truly see this as an opportunity to make a lasting difference for the planet, while generating a broad range of novel technologies with impact in many areas such as wireless power, communications, and sensing."

The Bren's gift has allowed researchers to overcome many early hurdles and funded the hiring of doctoral students to work on the project with a five-year commitment, notes Sergio Pellegrino, Caltech's Joyce and Kent Kresa Professor of Aerospace and Professor of Civil Engineering and co-director of SSPP. Pellegrino is also a senior research scientist at JPL, which Caltech manages for NASA.

"It allows us to think ahead," Pellegrino says. "Without that, it couldn't get done."

"Solar energy is the world's most abundant energy resource. However, sunlight is intermittent at the earth's surface. This ambitious project is a transformative approach to large-scale solar energy harvesting for the Earth that overcomes this intermittency and the need for energy storage, since sunlight shines continuously in space," says Harry A. Atwater, who is an SSPP researcher, Otis Booth Leadership Chair of the Division of Engineering and Applied Science and the Howard Hughes Professor of Applied Physics and Materials Science, and director of the Liquid Sunlight Alliance.

It has been said that competition inspires innovation.  While that may be true, collaboration can take innovation to actualization, at least sometimes.  Many large scale projects can be broken down into smaller manageable pieces which can then be broken down into even smaller, more reasonable pieces.  In a nutshell, conceptualizing, contracting, sub contracting and sub-sub-contracting.  The idea of solar power satellites has been dreamed of for quite a while, but instead of placing the entire burden on competing companies, get one company to focus on one component and another to focus on another and so on.  From there these various companies can utilize their own special networks to break down their objective and farm out those tasks to sub contractors, blah, blah, blah.
Title: Re: Solar Power Satellites
Post by: Proponent on 08/08/2021 03:24 pm
Haven't listen to show but did read webpage. They are using LEO satellite constellation and microwave beaming. Customer ground stations are likely to be large and expensive, but lot smaller than ones for GEO sats which are 100metres across.

He was very clear on the show that the plan is to use Molniya (https://en.wikipedia.org/wiki/Molniya_orbit) (mol-NEE-ya, by the way, meaning "lightning") orbits.  The powersats would spend most of their time near apogee, well above LEO.
Title: Re: Solar Power Satellites
Post by: Asteroza on 08/19/2021 03:12 am
Crosspost, China is back into SPS development apparently...

https://forum.nasaspaceflight.com/index.php?topic=54194.msg2279566#new (https://forum.nasaspaceflight.com/index.php?topic=54194.msg2279566#new)

The throwaway comment of a future test with a 20km altitude solar airship for beam downlink tests is kinda interesting as that would functionally be the same as those forever flying nearspace stratellite airships some companies have been pursuing, particularly for military purposes such as advanced airborne surveillance radar. A possible candidate might be "Tian heng", as discussed here

https://tompatrickjarvis.medium.com/facility-near-bosten-lake-xinjiang-china-possibly-airship-hangar-5c54b4f8f633 (https://tompatrickjarvis.medium.com/facility-near-bosten-lake-xinjiang-china-possibly-airship-hangar-5c54b4f8f633)

Title: Re: Solar Power Satellites
Post by: TrevorMonty on 08/20/2021 05:26 pm
Caltech's Space Solar Power design.


https://arstechnica.com/science/2021/08/where-the-sun-always-shines-putting-solar-in-space/

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Title: Re: Solar Power Satellites
Post by: su27k on 09/04/2021 03:51 am
Dr. Paul Jaffe from NRL was on The Space Show recently: https://thespaceshow.com/show/29-aug-2021/broadcast-3748-dr.-paul-jaffe, talking about their experiment on X-37B.
Title: Re: Solar Power Satellites
Post by: su27k on 09/16/2021 03:13 am
John Bucknell, the former SpaceX engineer who proposed a nuclear SSTO, started a Space Solar Power company: Virtus Solis Technologies (https://www.virtussolis.space/), he was on the spaceshow recently to promote this: https://thespaceshow.com/show/02-jul-2021/broadcast-3716-john-bucknell

The idea seems to be molniya orbit constellation, but not much details is offered. I get the impression it's like Starlink in terms of mass production of relatively small satellites, but for solar power.

2nd interview with John Bucknell: https://thespaceshow.com/show/12-sep-2021/broadcast-3755-john-bucknell, biggest news is he got an angel investor: Sheldon Kimber, CEO and founder of Intersect Power. The money is enough to fund a ground demo of power transmission, after that they'll need one more funding round to go to ground prototype of the satellite and another one for in orbit demo. His plan is 18 months to in orbit demo, 36 months to a 100MW commercial system.
Title: Re: Solar Power Satellites
Post by: Vultur on 09/16/2021 03:27 am
His plan is 18 months to in orbit demo, 36 months to a 100MW commercial system.

Is it just me, or does that seem super-optimistic, especially if not funded yet?
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 09/16/2021 03:39 am
His plan is 18 months to in orbit demo, 36 months to a 100MW commercial system.

Is it just me, or does that seem super-optimistic, especially if not funded yet?
3years to 100MW is very optimistic so is that 2.5c unit. There is definitely market at 50c ($500MWhr) for remote sites and islands. US military would pay lot more than that forward bases.





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Title: Re: Solar Power Satellites
Post by: su27k on 09/16/2021 04:06 am
His plan is 18 months to in orbit demo, 36 months to a 100MW commercial system.

Is it just me, or does that seem super-optimistic, especially if not funded yet?

I mean we can't let Elon have an monopoly on Elon TimeTM can we  ;)

The plan obviously assumes everything goes perfectly and he gets further funding, but I think a fast execution is exactly what is needed for SSP, let's just stop theorizing and start building because we already have all the technology needed, that's what I like about this guy's plan, "it's a manufacturing problem".
Title: Re: Solar Power Satellites
Post by: Vultur on 09/16/2021 05:06 am
His plan is 18 months to in orbit demo, 36 months to a 100MW commercial system.

Is it just me, or does that seem super-optimistic, especially if not funded yet?

I mean we can't let Elon have an monopoly on Elon TimeTM can we  ;)

The plan obviously assumes everything goes perfectly and he gets further funding, but I think a fast execution is exactly what is needed for SSP, let's just stop theorizing and start building because we already have all the technology needed, that's what I like about this guy's plan, "it's a manufacturing problem".



Both very good points -  I think you are right about fast execution being needed - but kind of skeptical about money.
Title: Re: Solar Power Satellites
Post by: Asteroza on 09/16/2021 08:23 am
His plan is 18 months to in orbit demo, 36 months to a 100MW commercial system.

Is it just me, or does that seem super-optimistic, especially if not funded yet?

I mean we can't let Elon have an monopoly on Elon TimeTM can we  ;)

The plan obviously assumes everything goes perfectly and he gets further funding, but I think a fast execution is exactly what is needed for SSP, let's just stop theorizing and start building because we already have all the technology needed, that's what I like about this guy's plan, "it's a manufacturing problem".



Both very good points -  I think you are right about fast execution being needed - but kind of skeptical about money.

Some people in the past have been put off by his handwaving of some difficult problems in ideas/designs he's proposed in the past (his air turbo rocket SSTO design using a NTR being probably the most recent one most people remember, aka NTTR or the nuclear SERJ).

https://forum.nasaspaceflight.com/index.php?topic=43344.msg1701830#msg1701830 (https://forum.nasaspaceflight.com/index.php?topic=43344.msg1701830#msg1701830)

He does have a past record of success however so he can't be written off either, especially if he gets real money.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 09/16/2021 05:44 pm
Well, the advantage of SBSP is that in principle it’s just engineering (and finance and regulation). No new science is needed.

I can think of worse things to blow a few billion on than a 100MW commercial-scale SBSP demonstrator.

It’s just a big, dumb telecom satellite optimized for transmission power and a big stationary receiver.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 09/16/2021 06:08 pm
Let’s just do some back of the envelope calculations here with existing Starlink satellites, probably the cheapest around.

They supposedly cost around $500,000 apiece and get on the order of 6kW of solar. Let’s say 5kW useful (and instead of powering a thruster and stuff, let’s say it’s all transmitted). Let’s say launch to GSO is free and the receiver is free. If the cost of capital is zero and the array lasts for 30 years, that means you cost is 38¢/kWh. Not too bad. Same as the price of residential electricity in Germany.

Heck, put a battery on it and keep it in LEO, and you get half as much energy, sure, but now you can use a much smaller aperture on both sides for the same frequency (although need a bunch of receivers around the world). The battery can be cheap as it only needs to last 45 minutes (but best cycle it gently because it’ll need to last for 200,000 cycles).
Title: Re: Solar Power Satellites
Post by: Robotbeat on 09/16/2021 06:32 pm
It could be pretty ridiculously cheap per watt with Starship, especially at lower frequency and if you get a huge site and can put it together in orbit. Solar panels are at 20¢/Watt (cells about half that). Radio transmitters, depending on efficiency and frequency, cost between 10¢ and $10 per Watt. The cheapest 10¢/Watt might be 80% efficient for a coherent magnetron (you can trick cheap magnetrons into being coherent) at 2.45GHz. At 2.45GHz and Geosynchronous altitude, that means to get a receiver and transmitter each 2km in diameter at 1000W/m^2 radio power, you need about 5GW of power to make it worthwhile.

Let’s say the aperture receives 80% of the energy and the rectifier is 80% efficient. So your overall efficiency is about 50%.

That means for every 1Watt received, you need about 2Watts of solar panels and transmitter plus 0.5Watts of radiator.

I think it can work. If you cleared regulatory hurdles and had a source of funding and if Starship works.

EDIT: Okay, I’ve convinced myself this can work and be competitive with ground solar. Dependent on $10/kg to LEO working.
Title: Re: Solar Power Satellites
Post by: su27k on 10/20/2021 07:19 am
UK government commissioned a report on Space Solar Power: Space based solar power: de-risking the pathway to net zero (https://www.gov.uk/government/publications/space-based-solar-power-de-risking-the-pathway-to-net-zero)

Quote
An independent study into the technical feasibility, cost and economics of space based solar power (SBSP), as a novel generation technology to help the UK deliver its net zero policy.

Details
Space based solar power (SBSP) is the concept of collecting solar power in a high earth orbit and beaming it securely to a fixed point on the earth. Its main attribute is the ability to deliver clean, baseload energy, day and night throughout the year and in all weathers. Recent technology and conceptual advances have made the concept worthy of consideration by the UK.

This independent study looks at the technical feasibility, cost and economics of space based solar power as a novel generation technology to help the UK deliver its net zero policy.

The executive summary contains:
* net zero context
* description and background of spaced based solar power
* engineering feasibility and risks
* cost and benefits
* conclusions and recommendations



Space Based Solar Power development
This study supports a case for developing SBSP, so the government is considering this further:

how it could potentially support innovation in the development of relevant technologies that are dual use which as a result could be used either in space based power systems or terrestrial power systems
We welcome your input:

Please register here (https://www.smartsurvey.co.uk/s/SBSP-EOI/) by 1 November 2021 giving a description of the dual-use technology you may wish to develop.



BEIS commissioned Frazer-Nash Consultancy to conduct the study. The technical reports which support this document are available on the Frazer-Nash website (https://www.fnc.co.uk/discover-frazer-nash/news/frazer-nash-report-for-uk-government-shows-feasibility-of-space-solar-power/):

* the Phase 1 report contains a review and analysis of the engineering feasibility of SBSP. It includes a review of leading SBSP concepts, an assessment of the underpinning technology maturity and engineering barriers to realise SBSP, as well as technological roadmaps for the development of a 10GW SBSP capability in the UK and internationally

* the Phase 2 report presents an assessment of the likely cost and economic contribution of SBSP as a possible future energy technology in the UK

The study supports a case for developing SBSP and the government is minded to fund an innovation programme looking at developing relevant technologies that also have broader terrestrial applications (https://www.gov.uk/government/collections/net-zero-innovation-portfolio#forthcoming-space-based-solar-power-innovation-programme) and could still contribute to UK’s climate change commitments, whether SBSP is deployed or not.

Report: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1020631/space-based-solar-power-derisking-pathway-to-net-zero.pdf

Technical documents supporting the report: https://www.fnc.co.uk/discover-frazer-nash/news/frazer-nash-report-for-uk-government-shows-feasibility-of-space-solar-power/
Title: Re: Solar Power Satellites
Post by: Asteroza on 10/20/2021 09:01 am
UK government commissioned a report on Space Solar Power: Space based solar power: de-risking the pathway to net zero (https://www.gov.uk/government/publications/space-based-solar-power-de-risking-the-pathway-to-net-zero)

Quote
An independent study into the technical feasibility, cost and economics of space based solar power (SBSP), as a novel generation technology to help the UK deliver its net zero policy.

Details
Space based solar power (SBSP) is the concept of collecting solar power in a high earth orbit and beaming it securely to a fixed point on the earth. Its main attribute is the ability to deliver clean, baseload energy, day and night throughout the year and in all weathers. Recent technology and conceptual advances have made the concept worthy of consideration by the UK.

This independent study looks at the technical feasibility, cost and economics of space based solar power as a novel generation technology to help the UK deliver its net zero policy.

The executive summary contains:
* net zero context
* description and background of spaced based solar power
* engineering feasibility and risks
* cost and benefits
* conclusions and recommendations



Space Based Solar Power development
This study supports a case for developing SBSP, so the government is considering this further:

how it could potentially support innovation in the development of relevant technologies that are dual use which as a result could be used either in space based power systems or terrestrial power systems
We welcome your input:

Please register here (https://www.smartsurvey.co.uk/s/SBSP-EOI/) by 1 November 2021 giving a description of the dual-use technology you may wish to develop.



BEIS commissioned Frazer-Nash Consultancy to conduct the study. The technical reports which support this document are available on the Frazer-Nash website (https://www.fnc.co.uk/discover-frazer-nash/news/frazer-nash-report-for-uk-government-shows-feasibility-of-space-solar-power/):

* the Phase 1 report contains a review and analysis of the engineering feasibility of SBSP. It includes a review of leading SBSP concepts, an assessment of the underpinning technology maturity and engineering barriers to realise SBSP, as well as technological roadmaps for the development of a 10GW SBSP capability in the UK and internationally

* the Phase 2 report presents an assessment of the likely cost and economic contribution of SBSP as a possible future energy technology in the UK

The study supports a case for developing SBSP and the government is minded to fund an innovation programme looking at developing relevant technologies that also have broader terrestrial applications (https://www.gov.uk/government/collections/net-zero-innovation-portfolio#forthcoming-space-based-solar-power-innovation-programme) and could still contribute to UK’s climate change commitments, whether SBSP is deployed or not.

Report: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1020631/space-based-solar-power-derisking-pathway-to-net-zero.pdf

Technical documents supporting the report: https://www.fnc.co.uk/discover-frazer-nash/news/frazer-nash-report-for-uk-government-shows-feasibility-of-space-solar-power/

Interesting that the consultant report baselined a CASSIOPeiA derivative GEO design, but felt SPS ALPHA was also suitable. Naturally, this being the UK, Skylon has a big part to play, but everybody knows it would be Starship delivering the goods...
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/20/2021 09:22 am
The reports make for interesting reading. Material supplies especially rare earth metals maybe limiting factor unless we source them in space which is totally different subject.

Land use comparisons had the nuclear power stations at lower than SBSP. Did they factor in mines to source fuel and locations to store spent fuel. Decommissioning costs of nuclear station are considerable along spent fuel storage costs, which don't have operational power station to pay for these ongoing costs.
While I like idea of placing rectenna over shallow sea, any underwater structures are likely to benefit fish life, above water structures maybe hazard for seabirds. Something owners of wind turbines found out hard way.



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Title: Re: Solar Power Satellites
Post by: Nilof on 10/20/2021 11:23 am
Imho, another big advantage of solar power satellites launched from the ground is that all the technology needed for them carries over to solar electric propulsion, since the primary bottleneck for high power SEP is the size of the largest demonstrated lightweight solar arrays.

So even if the demonstrator doesn't immediately become the perfect source for clean power to prevent global warming, it can definitely be what gets us to Mars, which isn't a bad consolation prize for the technology
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/20/2021 01:37 pm
Imho, another big advantage of solar power satellites launched from the ground is that all the technology needed for them carries over to solar electric propulsion, since the primary bottleneck for high power SEP is the size of the largest demonstrated lightweight solar arrays.

So even if the demonstrator doesn't immediately become the perfect source for clean power to prevent global warming, it can definitely be what gets us to Mars, which isn't a bad consolation prize for the technology
Robotic in space assembly and lower launch costs will be the other benefits of SBSP.

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Title: Re: Solar Power Satellites
Post by: Robotbeat on 10/20/2021 04:00 pm
Imho, another big advantage of solar power satellites launched from the ground is that all the technology needed for them carries over to solar electric propulsion, since the primary bottleneck for high power SEP is the size of the largest demonstrated lightweight solar arrays.

So even if the demonstrator doesn't immediately become the perfect source for clean power to prevent global warming, it can definitely be what gets us to Mars, which isn't a bad consolation prize for the technology
Robotic in space assembly and lower launch costs will be the other benefits of SBSP.

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Actually, Starship lowering the costs for human spaceflight may mean human in space assembly would be MUCH cheaper and faster than purely robotic assembly. Experiments in the earlier shuttle days show that astronauts can assemble structures much faster than any demonstrated space robot. A mass produced spacesuit is cheaper than a space rated robot. Heck, a mass produced spacesuit may be cheaper than a comparable terrestrial robot.


“Robots are cheaper/better for space” is one of those common assumptions that must be re-examined in light of what Starship enables.
Title: Re: Solar Power Satellites
Post by: Nilof on 10/20/2021 04:23 pm
Right, robots vs humans in space post starship will be closer to what the tradeoff looks like on Earth. If the task is easy to automate or if you you need to do exactly the same movement a million times, robots are better. Otherwise, humans tend to be very good at getting things done and automating should usually be the very last step
Title: Re: Solar Power Satellites
Post by: Paul451 on 10/20/2021 05:58 pm
While I like idea of placing rectenna over shallow sea, any underwater structures are likely to benefit fish life, above water structures maybe hazard for seabirds. Something owners of wind turbines found out hard way.

Fixed structures aren't dangerous to birds (unless they are reflective). Quite the contrary, the birds (and their waste) might be harmful to the structure.
Title: Re: Solar Power Satellites
Post by: LMT on 10/26/2021 02:55 am
I like idea of placing rectenna over shallow sea...

Placing the rectenna on a high-altitude platform removes water vapor from the line of sight.  This allows use of high-frequency microwaves:  e.g., 94 GHz.  This change can dramatically shrink rectenna and transmitter (https://forum.nasaspaceflight.com/index.php?topic=45597.msg2161393#msg2161393), with many potential SSP improvements associated.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/26/2021 09:16 am
I like idea of placing rectenna over shallow sea...

Placing the rectenna on a high-altitude platform removes water vapor from the line of sight.  This allows use of high-frequency microwaves:  e.g., 94 GHz.  This change can dramatically shrink rectenna and transmitter (https://forum.nasaspaceflight.com/index.php?topic=45597.msg2161393#msg2161393), with many potential SSP improvements associated.
This relies on light weight superconductors to transfer power ground from floating receiver 20km altitude. Superconductors need to be kept cool, that is 20kms of conductor in pipe surrounded by coolant.
HAP may haclve future but not best place to start. Better to start with less efficient low tech version first.

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Title: Re: Solar Power Satellites
Post by: LMT on 10/26/2021 01:30 pm
I like idea of placing rectenna over shallow sea...

Placing the rectenna on a high-altitude platform removes water vapor from the line of sight.  This allows use of high-frequency microwaves:  e.g., 94 GHz.  This change can dramatically shrink rectenna and transmitter (https://forum.nasaspaceflight.com/index.php?topic=45597.msg2161393#msg2161393), with many potential SSP improvements associated.
This relies on light weight superconductors to transfer power ground from floating receiver 20km altitude. Superconductors need to be kept cool, that is 20kms of conductor in pipe surrounded by coolant.
HAP may haclve future but not best place to start. Better to start with less efficient low tech version first.

Commercial SSP will require high efficiency, so we'll have to look beyond low tech for useful methods.

And yes, an HTS cable needs coolant.  You'd explore ways to minimize coolant there, and overall cable mass.  Notably, HTS tape can deliver extraordinary current today, even 5000 A/mm2 (https://forum.nasaspaceflight.com/index.php?topic=45674.msg2087083#msg2087083).  With high voltage typical of HTS power delivery, e.g., 200,000 V, P = V I gives a 1 GW cable with an HTS core of just 1 mm2.  LN2 coolant for such a tiny HTS core could be supplied readily from a cryocooler on the high-altitude platform. 

Alternately, you might bond a string of optical cryocooler crystals to the core, and dispense with liquid coolant.  Example:  CryoRay coolers (http://cryoraycoolers.com/index.htm)

Quote
CryoRay coolers are solid-state cryogenic refrigerators capable of higher efficiencies at lower temperatures than any other solid-state technology.  Unlike traditional cooling technologies that rely on compressed gasses or the thermoelectric effect, CryoRay coolers extract heat by an optical mechanism.   The active element of a CryoRay device cools by absorbing laser light at one frequency and reemitting it at high frequencies (See Technology (http://cryoraycoolers.com/index_files/Technology.htm)).  By this process CryoRay coolers achieve extremely low temperatures, less than 100 K (-280 F), far colder than is possible with thermoelectric refrigerators.  Because CryoRay coolers are solid-state devices with no moving parts or fluids, they are very reliable, generate no vibrations and require no maintenance.
Title: Re: Solar Power Satellites
Post by: su27k on 11/09/2021 03:02 am
https://twitter.com/Capoglou/status/1457817125960273924
Quote
Join us online on December 9th & 10th from 13:00 to 18:00pm CET for an international workshop to plan ESA’s next steps towards providing clean energy from space for a greener Earth: Space-based Solar Power for Net Zero
 https://indico.esa.int/event/399/ #SBSP #COP26 #ClimateAction #Energy


Space-based Solar Power for Net Zero  (https://indico.esa.int/event/399/)

Quote from: ESA
– An international workshop to plan ESA’s next steps towards providing clean energy from space for a greener Earth.

Want to know about how space could provide clean energy to society to enable the transition to a Net Zero carbon world by 2050?

Interested to find out what the European Space Agency is doing to see if the idea of collecting energy in space and sending it to Earth is credible and realisable?

Then please join us online on December 9th and 10th, from 13:00 to 18:00 pm CET, to meet and hear from international experts in the field and to discuss and learn about the vital role that Space-based Solar Power  (SBSP) could play in the fight against climate change and help ESA shape its future programmes.

Workshop Day 1 Registration https://esait.webex.com/esait/j.php?RGID=r75041ebaac57d45288fae9f38696c376

Workshop Day 2 Registration https://esait.webex.com/esait/j.php?RGID=r715c11a76a817c6d2ab1730c0d92d985
Title: Re: Solar Power Satellites
Post by: Robotbeat on 11/09/2021 06:49 am
SBSP doesn’t need Super high efficiency like HTS cables and stuff. Works fine without it. But if HTS cables win the cost and performance trade, then great. But let’s not just add tech just for the gee-whiz factor.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/09/2021 03:04 pm
I like idea of placing rectenna over shallow sea...

Placing the rectenna on a high-altitude platform removes water vapor from the line of sight.  This allows use of high-frequency microwaves:  e.g., 94 GHz.  This change can dramatically shrink rectenna and transmitter (https://forum.nasaspaceflight.com/index.php?topic=45597.msg2161393#msg2161393), with many potential SSP improvements associated.
This relies on light weight superconductors to transfer power ground from floating receiver 20km altitude. Superconductors need to be kept cool, that is 20kms of conductor in pipe surrounded by coolant.
HAP may haclve future but not best place to start. Better to start with less efficient low tech version first.

Commercial SSP will require high efficiency, so we'll have to look beyond low tech for useful methods.

And yes, an HTS cable needs coolant.  You'd explore ways to minimize coolant there, and overall cable mass.  Notably, HTS tape can deliver extraordinary current today, even 5000 A/mm2 (https://forum.nasaspaceflight.com/index.php?topic=45674.msg2087083#msg2087083).  With high voltage typical of HTS power delivery, e.g., 200,000 V, P = V I gives a 1 GW cable with an HTS core of just 1 mm2.  LN2 coolant for such a tiny HTS core could be supplied readily from a cryocooler on the high-altitude platform. 

Alternately, you might bond a string of optical cryocooler crystals to the core, and dispense with liquid coolant.  Example:  CryoRay coolers (http://cryoraycoolers.com/index.htm)

Quote
CryoRay coolers are solid-state cryogenic refrigerators capable of higher efficiencies at lower temperatures than any other solid-state technology.  Unlike traditional cooling technologies that rely on compressed gasses or the thermoelectric effect, CryoRay coolers extract heat by an optical mechanism.   The active element of a CryoRay device cools by absorbing laser light at one frequency and reemitting it at high frequencies (See Technology (http://cryoraycoolers.com/index_files/Technology.htm)).  By this process CryoRay coolers achieve extremely low temperatures, less than 100 K (-280 F), far colder than is possible with thermoelectric refrigerators.  Because CryoRay coolers are solid-state devices with no moving parts or fluids, they are very reliable, generate no vibrations and require no maintenance.
https://twitter.com/Capoglou/status/1457817125960273924
Quote
Join us online on December 9th & 10th from 13:00 to 18:00pm CET for an international workshop to plan ESA’s next steps towards providing clean energy from space for a greener Earth: Space-based Solar Power for Net Zero
 https://indico.esa.int/event/399/ #SBSP #COP26 #ClimateAction #Energy


Space-based Solar Power for Net Zero  (https://indico.esa.int/event/399/)

Quote from: ESA
– An international workshop to plan ESA’s next steps towards providing clean energy from space for a greener Earth.

Want to know about how space could provide clean energy to society to enable the transition to a Net Zero carbon world by 2050?

Interested to find out what the European Space Agency is doing to see if the idea of collecting energy in space and sending it to Earth is credible and realisable?

Then please join us online on December 9th and 10th, from 13:00 to 18:00 pm CET, to meet and hear from international experts in the field and to discuss and learn about the vital role that Space-based Solar Power  (SBSP) could play in the fight against climate change and help ESA shape its future programmes.

Workshop Day 1 Registration https://esait.webex.com/esait/j.php?RGID=r75041ebaac57d45288fae9f38696c376

Workshop Day 2 Registration https://esait.webex.com/esait/j.php?RGID=r715c11a76a817c6d2ab1730c0d92d985
Nice to see major space powers start to seriously consider SSP. If only it had received few % of what they've invested in fusion research we'd be lot further along. Admittedly high launch costs have been big show stopper to making it financially viable and still are. That doesn't means small demo projects can't be flown to retry lot of technically risks.



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Title: Re: Solar Power Satellites
Post by: su27k on 11/26/2021 02:32 am
Financial Times produced a short video about Space Solar Power, interviewed a few supporters: https://www.ft.com/video/2f48b8e4-bb5a-4d90-b267-e33d9a59804c
Title: Re: Solar Power Satellites
Post by: su27k on 12/22/2021 03:27 am
AFRL and Northrop Grumman test key hardware for space-based solar power experiment (https://spacenews.com/afrl-and-northrop-grumman-test-key-hardware-for-space-based-solar-power-experiment/)

Quote from: SpaceNews
A satellite solar panel designed by Northrop Grumman to harvest energy in space to be beamed back to Earth performed successfully in lab tests, clearing the way for the technology to be launched to orbit in a military experiment planned for 2025.

The demonstration — conducted recently at a Northrop Grumman facility in Linthicum, Maryland — was in support of an experiment funded by the Air Force Research Laboratory to collect solar power in outer space for use on Earth.

AFRL said Dec. 21 that the “sandwich tile” designed by Northrop Grumman for this experiment successfully converted solar energy to radio frequency power, “a fundamental step required to pave the way for a large-scale solar power collection system in space.” To make this work, receiving antennas on Earth would be used to transform the RF energy into usable power.
Title: Re: Solar Power Satellites
Post by: su27k on 12/30/2021 02:08 am
https://twitter.com/Capoglou/status/1457817125960273924
Quote
Join us online on December 9th & 10th from 13:00 to 18:00pm CET for an international workshop to plan ESA’s next steps towards providing clean energy from space for a greener Earth: Space-based Solar Power for Net Zero
 https://indico.esa.int/event/399/ #SBSP #COP26 #ClimateAction #Energy


Space-based Solar Power for Net Zero  (https://indico.esa.int/event/399/)

Video for this meeting is out:

https://www.youtube.com/watch?v=m5iHr5ssVV4&list=PLbyvawxScNbscJ80aDmOPZ-oR0jJ97H8L

https://www.youtube.com/watch?v=-dgtoas0pCU&list=PLbyvawxScNbscJ80aDmOPZ-oR0jJ97H8L&index=2

https://www.youtube.com/watch?v=VTLky82GmdA&list=PLbyvawxScNbscJ80aDmOPZ-oR0jJ97H8L&index=3
Title: Re: Solar Power Satellites
Post by: su27k on 01/26/2022 02:33 am
On National Security | Solar power from space: Will it ever get off the ground? (https://spacenews.com/on-national-security-solar-power-from-space-will-it-ever-get-off-the-ground/)

Quote from: SpaceNews
Satellites in space harvesting sunlight and turning solar energy into usable power for applications on Earth is an idea that has been studied for decades. But even though the United States was a pioneer in this technology, government interest in taking it from the lab to orbit has been tepid at best.

The U.S. military is now trying to revive the effort. The Naval Research Laboratory launched an experiment in 2020 aboard the Air Force’s X-37B space plane that successfully tested hardware to capture sunlight and convert it into direct current electrical energy.

The NRL experiment, however, was only an in-space demonstration and not intended to beam the power captured in space back to the ground. That capability will be attempted by the Air Force Research Laboratory, if all goes as planned, in a $100 million experiment projected to launch in 2025.
Title: Re: Solar Power Satellites
Post by: Paul451 on 01/26/2022 03:45 am
Quote
hardware to capture sunlight and convert it into direct current electrical energy.

Uhhh... a solar panel?

Title: Re: Solar Power Satellites
Post by: gparker on 01/31/2022 02:32 am
Quote
hardware to capture sunlight and convert it into direct current electrical energy.

Uhhh... a solar panel?

Not just a solar panel: a repeatable "sandwich module" with a solar panel on the front, an RF converter in the middle, and an antenna on the back. (The 2020 launch only tested the first two components; the antenna would have caused too much interference for the vehicle and its other experiments.)

NRL PRAM Mission: One Year and Still Going (https://www.navy.mil/Press-Office/Press-Releases/display-pressreleases/Article/2652805/nrl-pram-mission-one-year-and-still-going/)
Title: Re: Solar Power Satellites
Post by: qraal on 01/31/2022 09:01 am
A question not often explored, which I attempt an answer to, is how do ground-based systems compare with space-based:

SPACE BASED SOLAR POWER VS EARTH-BASED-WITH-STORAGE – PART 1 (https://crowlspace.com/?p=3672)

SPACE BASED SOLAR POWER VS EARTH-BASED-WITH-STORAGE – PART 2 (https://crowlspace.com/?p=3693)

I was quite surprised by the results, but I've been made aware I missed one of the major consumables of Starship operations - liquid nitrogen for super-chilling the propellants. I don't think it'll be much different, but something to keep in mind.

The stretched Starship Tanker, able to deliver 220 tons, will alter the number of launches needed to refuel a GEO bound Starship freighter.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 01/31/2022 04:17 pm
A question not often explored, which I attempt an answer to, is how do ground-based systems compare with space-based:

SPACE BASED SOLAR POWER VS EARTH-BASED-WITH-STORAGE – PART 1 (https://crowlspace.com/?p=3672)

SPACE BASED SOLAR POWER VS EARTH-BASED-WITH-STORAGE – PART 2 (https://crowlspace.com/?p=3693)

I was quite surprised by the results, but I've been made aware I missed one of the major consumables of Starship operations - liquid nitrogen for super-chilling the propellants. I don't think it'll be much different, but something to keep in mind.

The stretched Starship Tanker, able to deliver 220 tons, will alter the number of launches needed to refuel a GEO bound Starship freighter.
Here is revenue returns on your 3GW power station.

3(GW)x 8760(hrs year)×$50,000($0.05 kwh) =$1.314B a year.

There is significant amount of labour involved in maintenance of ground solar system. Space system only has rectanna and power station both of which are low maintenance.

Space assets will still need odd launch and robotic repairs. These should be low based on failure rate of GEO satellites

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Title: Re: Solar Power Satellites
Post by: Darkseraph on 02/03/2022 04:47 pm
http://www.parabolicarc.com/2022/02/02/russian-space-systems-developing-space-based-solar-power-satellite/


Apparently Russia is beginning to experiment with space solar power because it has far flung regions
with limited insolation. This scheme seems to be a store and forward strategy using lasers in lower earth
orbits. I can see some of the appeal of space solar power for countries with sparse inaccessible areas
in the same way that it's been proposed as solution to rural broadband. Or for remote military bases in artic
regions instead of having to ship in diesel or deal with the dangers and expenses of nuclear.

It also could be a front for directed energy space weapons though...
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 02/03/2022 08:01 pm


http://www.parabolicarc.com/2022/02/02/russian-space-systems-developing-space-based-solar-power-satellite/


It also could be a front for directed energy space weapons though...

Also good for removing space debris they create from blowing up satellites.



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Title: Re: Solar Power Satellites
Post by: su27k on 03/13/2022 01:25 am
https://twitter.com/ESA_Tech/status/1502255405858177029

Quote
Latest developments in space-based solar power: @esa has charged Frazer-Nash Consultancy & Roland Berger with creating 2 independent cost-benefit analysis studies, evaluating the ‘business case’ of #SBSP for Europe, reporting at the end of summer 2022 https://esa.int/Enabling_Support/Preparing_for_the_Future/Discovery_and_Preparation/ESA_reignites_space-based_solar_power_research
Title: Re: Solar Power Satellites
Post by: su27k on 04/06/2022 02:36 am
A Game Changer in the Fight Against Climate Change | Opinion (https://www.newsweek.com/game-changer-fight-against-climate-change-opinion-1693929)

Quote from: newsweek.com
Elon Musk's Starship rocket is poised for liftoff. The billionaire inventor recently announced that the massive new rocket system developed by his SpaceX corporation is approaching technical readiness—and that many of the remaining hurdles are administrative in nature.

<snip>

All this matters a great deal, not least for environmentalists because it will make the concept of Space Solar Power both technically and economically feasible.

Designs for individual solar power satellite (such as NASA's SPS-ALPHA) weigh in at about 8,000 metric tons, and—once deployed—will deliver about 2 gigawatts of energy back to Earth. And unlike terrestrial solar generation, which is intermittent, Space Solar Power Satellites can deliver constant power appropriate to the 24 hour needs of cities and industry and will be able to compete directly with coal and nuclear.
Title: Re: Solar Power Satellites
Post by: CameronD on 04/06/2022 11:40 pm
A Game Changer in the Fight Against Climate Change | Opinion (https://www.newsweek.com/game-changer-fight-against-climate-change-opinion-1693929)

Quote from: newsweek.com
Elon Musk's Starship rocket is poised for liftoff. The billionaire inventor recently announced that the massive new rocket system developed by his SpaceX corporation is approaching technical readiness—and that many of the remaining hurdles are administrative in nature.

<snip>

All this matters a great deal, not least for environmentalists because it will make the concept of Space Solar Power both technically and economically feasible.

Designs for individual solar power satellite (such as NASA's SPS-ALPHA) weigh in at about 8,000 metric tons, and—once deployed—will deliver about 2 gigawatts of energy back to Earth. And unlike terrestrial solar generation, which is intermittent, Space Solar Power Satellites can deliver constant power appropriate to the 24 hour needs of cities and industry and will be able to compete directly with coal and nuclear.

An interesting segue from Starship via greenies to SBSP, but I guess that's why it's an opinion piece.

Using the words of a beloved but equally fanciful movie character: From reality to beyond!!!
Title: Re: Solar Power Satellites
Post by: su27k on 04/24/2022 02:23 am
US Navy wirelessly beams 1.6 kW of power a kilometer using microwaves (https://newatlas.com/energy/us-navy-beams-1-6-kw-power-kilometer-microwaves/)

Quote from: newatlas.com
In what it describes as the most significant demonstration of its kind in half a century, the US Naval Research Laboratory (NRL) beamed 1.6 kW of power over a kilometer (3,280 ft) using a microwave beam at the US Army Research Field in Maryland.

<snip>

Despite initial doubts, microwave beaming turns out to be surprisingly efficient and the NRL team led by Christopher Rodenbeck, Head of the Advanced Concepts Group, has been tasked by the Defense Department with developing the Safe and Continuous Power bEaming – Microwave (SCOPE-M) project to explore the practicality of fielding the technology.

Using a 10-GHz microwave beam, SCOPE-M set up at two locations. The first was the US Army Research Field at Blossom Point, Maryland, and the second was at the Haystack Ultra Wideband Satellite Imaging Radar (HUSIR) transmitter at MIT in Massachusetts. The frequency was chosen because it was not only able to beam even in heavy rain with a loss of power of under five percent, it's also safe to use under international standards in the presence of birds, animals, and people. This means the system doesn't need the automatic cutouts developed for earlier laser-based systems.
Title: Re: Solar Power Satellites
Post by: LMT on 04/24/2022 09:40 pm
Quote from: Szondy
The frequency [10 GHz] was chosen because it [can] beam even in heavy rain with a loss of power of under five percent...

The paraphrased author, researcher Jaffe (https://www.nrl.navy.mil/Media/News/Article/3005806/nrl-conducts-successful-terrestrial-microwave-power-beaming-demonstration/), has a generous notion of "heavy rain" there. 

Losses are much higher in a typical "heavy" rainstorm, which is why 10 GHz isn't used outside controlled experiment.  Gavan and Tapuchi 2010, Fig. 11.

Quote from: Jaffe et al.
"...we can exploit scattering (https://www.dvidshub.net/video/embed/840238) from terrain in the path of the beam in order to increase power density at the target..."

Speaking of controlled experiment, yes, one can "exploit scattering" off a flat grass strip.

Nice controlled reflection point (https://urgentcomm.com/1998/07/01/microwave-path-design-the-basics-3/) there. 

:)

Refs.

Gavan, J. and Tapuchi, S., 2010. Microwave wireless-power transmission to high-altitude-platform systems. (https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7911078) The Radio Science Bulletin, 334, pp.25-42.
Title: Solar Power Satellites
Post by: Star One on 04/25/2022 08:57 am
Quote
The UK government is reportedly considering a £16 billion proposal to build a solar power station in space.

Yes, you read that right. Space-based solar power is one of the technologies to feature in the government’s Net Zero Innovation Portfolio. It has been identified as a potential solution, alongside others, to enable the UK to achieve net-zero by 2050.

https://thenextweb.com/news/uk-wants-to-build-massive-solar-station-in-space-how
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 04/25/2022 10:37 am
If UK is serious about this then they need to start developing a large domestic RLV. That way all money spent on launch stays in country.



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Title: Re: Solar Power Satellites
Post by: Greg Hullender on 04/25/2022 05:07 pm
It has now been eight years since I made the original post in this thread. It's a little discouraging to see just how little progress has been made--probably because so little has been invested in this technology. No one has even launched a satellite to test the idea at this point.

However, it does seem that the UK is planning to do something--about eight years from now. I guess we'll have to wait and see.
Title: Re: Solar Power Satellites
Post by: LMT on 04/25/2022 09:47 pm
Quote from: TNW
The UK government is reportedly considering a £16 billion proposal to build a solar power station in space.

Notionally ~ 10x the price of an equivalent nuclear plant (South Korean data (https://www.vox.com/2016/2/29/11132930/nuclear-power-costs-us-france-korea)).  Tough numbers.

Also, nuclear plants aren't subject to SSP GEO debris risk (https://forum.nasaspaceflight.com/index.php?topic=45597.msg2158980#msg2158980).  GEO flux is high: a terrible and persistent risk to SSP at, say, 1.7-km scale (https://thenextweb.com/news/uk-wants-to-build-massive-solar-station-in-space-how).  That scale of GEO SSP construction would set up conditions for a Kessler effect cascade (https://www.esa.int/Safety_Security/Space_Debris/ESA_s_Space_Environment_Report_2022), yes?  How to prevent that, and at what (additional) cost? 

https://youtu.be/X9aqfIAJrJo
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/26/2022 12:41 am
Quote from: TNW
The UK government is reportedly considering a £16 billion proposal to build a solar power station in space.

Notionally ~ 10x the price of an equivalent nuclear plant (South Korean data (https://www.vox.com/2016/2/29/11132930/nuclear-power-costs-us-france-korea)).  Tough numbers.

Not at all. Hinkley Point C cost is about £23B for 3.2GW, plus price of the fuel. So £16B for 2GW space based solar is very close to the same price as a large nuclear power plant currently.
Title: Re: Solar Power Satellites
Post by: LMT on 04/26/2022 02:10 am
Quote from: TNW
The UK government is reportedly considering a £16 billion proposal to build a solar power station in space.

Notionally ~ 10x the price of an equivalent nuclear plant (South Korean data (https://www.vox.com/2016/2/29/11132930/nuclear-power-costs-us-france-korea)).  Tough numbers.


Not at all. Hinkley Point C cost is about £23B for 3.2GW, plus price of the fuel. So £16B for 2GW space based solar is very close to the same price as a large nuclear power plant currently.

Fix with SSP, or efficiency consulting?

--

A GEO SSP system's ability to kick-start the Kessler effect (https://www.esa.int/Safety_Security/Space_Debris/ESA_s_Space_Environment_Report_2022) deserves more attention.  Multi-km SSP would be an immense Kessler cascade generator.

And when you consider the present blindness to sub-30-cm debris (and meteoroids) in GEO (https://www.nap.edu/read/4765/chapter/1)...

Quote
In 1993 (https://padeye.news/perseids-and-the-olympus-1-incident-heres-what-happened-in-1993/), a Perseid meteor destroyed a satellite launched four years earlier by the European Space Agency. It was Olympus-1, the largest civilian telecommunications satellite ever built at the time, costing up to $850 million.

The impact generated a plasma cloud that short-circuited the satellite’s attitude control system. The ground technicians were able to prevent it from spiraling out of control, but they had to use up all the fuel, forcing the operations center to take the Olympus-1 out of service permanently.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/26/2022 04:30 am
Start a new thread to fear monger about Kessler Syndrome, please.
Title: Re: Solar Power Satellites
Post by: LMT on 04/26/2022 05:13 am
Start a new thread to fear monger about Kessler Syndrome, please.

Or posters could examine this terrible SSP risk, just as they like. 

SSP risk-reduction ideas from 2014 (https://www.thespacereview.com/article/2602/1):

Quote
In 2009, retired astrophysicist Donald Kessler, who started
NASA’s work on orbital debris more than 30 years ago,
stated, 'large structures such as those considered… for building
solar power stations in Earth orbit could set up a situation
where a single satellite failure could lead to cascading failures
of many satellites.'
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/26/2022 05:19 am
Yeah, you’re just trying to sink the thread by concern trolling it and then ignoring calls to make your own thread about that, using it as an excuse for more concern trolling. Make the thread or I will. I want to actually discuss the broader topic of SBSP.
Title: Re: Solar Power Satellites
Post by: M.E.T. on 04/26/2022 08:12 am
Yeah, you’re just trying to sink the thread by concern trolling it and then ignoring calls to make your own thread about that, using it as an excuse for more concern trolling. Make the thread or I will. I want to actually discuss the broader topic of SBSP.

So does the business case close?

As always, that’s my main focus in almost every thread, being one of those pesky MBA types that Elon quite justifiably takes regular shots at. :) I just happen to be one that is a bit obsessed with space.

So, even with Starship, does SBSP make financial sense? I recall that Elon is doubtful about it.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 04/26/2022 08:56 am


Quote from: TNW
The UK government is reportedly considering a £16 billion proposal to build a solar power station in space.

Notionally ~ 10x the price of an equivalent nuclear plant (South Korean data (https://www.vox.com/2016/2/29/11132930/nuclear-power-costs-us-france-korea)).  Tough numbers.

Not at all. Hinkley Point C cost is about £23B for 3.2GW, plus price of the fuel. So £16B for 2GW space based solar is very close to the same price as a large nuclear power plant currently.

There is also decommissioning costs for nuclear power station. SSP station shouldn't ever need decommissioning, most likely be upgraded overtime.

I wouldn't of thought debris would be that much of issue in GEO as all satellites are nearly stationary relative to each other.  LEO is different as there a satellites crossing paths at 90degrees with impact speeds of 1000s kmh.

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Title: Re: Solar Power Satellites
Post by: edzieba on 04/26/2022 10:58 am
SSP station shouldn't ever need decommissioning, most likely be upgraded overtime.
Decomissioning for a gEO-slot SSP station would require a similar sort of graveyard orbit raise to decommissioning any other end-of-life GEO satellite. Plus contingency planning for disposal of a failed uncommandable SSP station (visiting it to shove it out of the way). Hopefully less than a whole-cycle fission reactor decommissioning effort, but not zero.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/26/2022 12:28 pm
Yeah, you’re just trying to sink the thread by concern trolling it and then ignoring calls to make your own thread about that, using it as an excuse for more concern trolling. Make the thread or I will. I want to actually discuss the broader topic of SBSP.

So does the business case close?

As always, that’s my main focus in almost every thread, being one of those pesky MBA types that Elon quite justifiably takes regular shots at. :) I just happen to be one that is a bit obsessed with space.

So, even with Starship, does SBSP make financial sense? I recall that Elon is doubtful about it.
im not sure it does close. At least with Starship, it has a chance, but…

With renewables and batteries already pretty cheap, even nuclear struggles financially.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 04/26/2022 04:17 pm


SSP station shouldn't ever need decommissioning, most likely be upgraded overtime.
Decomissioning for a gEO-slot SSP station would require a similar sort of graveyard orbit raise to decommissioning any other end-of-life GEO satellite. Plus contingency planning for disposal of a failed uncommandable SSP station (visiting it to shove it out of the way). Hopefully less than a whole-cycle fission reactor decommissioning effort, but not zero.

Gigawatt SSP will be huge robotically assembled and maintained structure. No need for end of life as its completely modular. Solar panels and electronics will most likely need regular upgrades. Booms and cabling should only need replacing if damaged.





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Title: Re: Solar Power Satellites
Post by: DanClemmensen on 04/26/2022 04:32 pm


SSP station shouldn't ever need decommissioning, most likely be upgraded overtime.
Decomissioning for a gEO-slot SSP station would require a similar sort of graveyard orbit raise to decommissioning any other end-of-life GEO satellite. Plus contingency planning for disposal of a failed uncommandable SSP station (visiting it to shove it out of the way). Hopefully less than a whole-cycle fission reactor decommissioning effort, but not zero.

Gigawatt SSP will be huge robotically assembled and maintained structure. No need for end of life as its completely modular. Solar panels and electronics will most likely need regular upgrades. Booms and cabling should only need replacing if damaged.

This assumes ongoing maintenance in space. I think this is a perfectly reasonable assumption, but it depends on cheap access to space for large payloads. There is still a "decommisioning" component: what to do with the old modules you replace? I think the answer in implicit in your model: you return the old modules to Earth for recycling or disposal.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/26/2022 04:39 pm
Deorbiting chunks to burn up in the atmosphere, or impacting the Moon, or going to a heliocentric disposal orbit.

For large enough structures, recycling in orbit starts to make sense. At least grinding it up and using it as radiation shielding or something.
Title: Re: Solar Power Satellites
Post by: LMT on 04/26/2022 06:22 pm
I wouldn't of thought debris would be that much of issue in GEO as all satellites are nearly stationary relative to each other. 

There are many inclined geosync orbits, e.g., RADUGA 29 (https://www.n2yo.com/satellite/?s=22557), at 14.6°.

Beyond that, what speed would an exploding tank acquire?  Think of Olympus-1 (https://forum.nasaspaceflight.com/index.php?topic=35013.msg2363335#msg2363335) with a (fortunately, hypothetical) Perseid hit on bipropellant tanks.

Kessler has reason to worry about SSP in GEO (https://forum.nasaspaceflight.com/index.php?topic=35013.msg2363366#msg2363366), yes?

what to do with the old modules you replace? I think the answer in implicit in your model: you return the old modules to Earth for recycling or disposal.

If you can get your GEO debris hazard under control, somehow, then the scale of your structure and its expense suggest on-site refurb. 

Conceivably, you could rotate some segment of that SSP structure and its docked crew facility, with AG factory floor.  You'd be shipping refurb components, or raw materials for printed refurb components, instead of massive replacement systems.

You might think to optimize SSP system design for ease of refurb.
Title: Re: Solar Power Satellites
Post by: high road on 04/27/2022 12:54 pm
It has now been eight years since I made the original post in this thread. It's a little discouraging to see just how little progress has been made--probably because so little has been invested in this technology. No one has even launched a satellite to test the idea at this point.

The problem is the high risk of massive cost overruns due to necessary technology not being ready. In space assembly, robotic maintenance, can't plan a big sat until those have proven to work. And even before building a sat, beaming microwave over long distances is hardly tested on earth either. Last I heard was a km. That's not a lot. And you need to get rid of the waste heat of the 40% energy lost during transformation to microwaves. That's a considerable extra effort in space
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/27/2022 01:02 pm
Beaming microwave is regularly done over 10s of thousands of kilometers. :) my phone is receiving microwaves from thousands of kilometers right at this moment.

As far as waste heat, you don’t generate a full 40% as waste heat on the satellite. A magnetron, for instance, is typically 82% efficient and can be as high as 90% or more. Some of the losses you see aren’t manifested as waste heat on the satellite but in stray/absorbed beam (which has its own problems) or on the rectenna side.
Title: Re: Solar Power Satellites
Post by: CameronD on 04/28/2022 01:08 am
Beaming microwave is regularly done over 10s of thousands of kilometers. :) my phone is receiving microwaves from thousands of kilometers right at this moment.

You have a sat phone?  Cool!  They don't require a receive power in the gigawatt range to operate though.

I seem to remember proposals way back in the 70's to simply use mirrors - no need for inefficient, short-life and potentially polluting* solar panels in space, just focus a GEO mirror on a relatively tiny spot on earth and hey presto it's daylight 24/7.


*= With tree-huggers the world over currently hassling the aviation sector about their 2% of global emissions, just wait until they do the calculations on atmospheric pollution from discarded satellites!! :-X
Title: Re: Solar Power Satellites
Post by: Robotbeat on 04/28/2022 01:27 am
Beaming microwave is regularly done over 10s of thousands of kilometers. :) my phone is receiving microwaves from thousands of kilometers right at this moment.

You have a sat phone?  Cool!  They don't require a receive power in the gigawatt range to operate though.

I seem to remember proposals way back in the 70's to simply use mirrors - no need for inefficient, short-life and potentially polluting* solar panels in space, just focus a GEO mirror on a relatively tiny spot on earth and hey presto it's daylight 24/7.


*= With tree-huggers the world over currently hassling the aviation sector about their 2% of global emissions, just wait until they do the calculations on atmospheric pollution from discarded satellites!! :-X
GPS.

The problem with mirrors is you can't focus the Sun smaller than like 200 miles in diameter on the surface of the Earth from geosynchronous orbit.
Title: Re: Solar Power Satellites
Post by: LMT on 04/28/2022 03:02 am
High-efficiency power transmission in the Fresnel zone (within fraunhofer distance (https://forum.nasaspaceflight.com/index.php?topic=45597.msg2161393#msg2161393)) is simulated in MATLAB, in Hutson and Rodenbeck 2021 (https://apps.dtic.mil/sti/pdfs/AD1128170.pdf).  See source code in appendices.

Quote
This program allows the calculation of the electromagnetic fields a specified distance away from a transmitting antenna aperture, and the power incident upon a receiving array at that range. The simulated transmitter may be a continuous antenna or a phased array, each of which will produce slightly different models...

The application also possesses the ability to perform power transfer optimization. The 'Autofocus' switch enables or disables phase focusing at the specified distance, while the 'Optimize' option performs a simple optimization algorithm on the source amplitude distribution...

Fig. 8:  Fraunhofer distance?

Refs.

Hutson, J.V. and Rodenbeck, C.T., 2021. Computation of Power Beaming Efficiency in the Fresnel Zone with Application to Amplitude and Phase Optimization. (https://apps.dtic.mil/sti/pdfs/AD1128170.pdf) Naval Research Laboratory.
Title: Re: Solar Power Satellites
Post by: su27k on 05/28/2022 01:14 pm
https://twitter.com/jeff_foust/status/1530179283360092165

Quote
At #ISDC2022 (Int’l Space Development Conference), Nikolai Joseph of NASA’s Office of Technology, Policy and Strategy said the office is starting a new study to revisit space-based solar power. Idea it to revisit existing proposals, updating technology, cost, policy issues.



Not many details about the study itself, which is scheduled to be completed and rolled out at IAC in September, but he said NASA will be updating existing proposed architectures for space-based solar, rather than developing new ones.


NASA to reexamine space-based solar power (https://spacenews.com/nasa-to-reexamine-space-based-solar-power/)

Quote from: SpaceNews
In his speech, Joseph said the study, besides looking at costs and policy issues, will also examine public perception of space-based solar power. “Public perception is something we don’t talk much about,” he said, noting that when he explains how such systems would beam power back to Earth, people ask what that would mean for birds flying through those beams. “I don’t think it’s going to be a problem, but I don’t fully know and I need to understand that.”

He said the study could provide benefits even if it concludes SBSP isn’t feasible. “It’s a wonderful strawman for understanding how we attack big problems like this,” he said. “It’s also a great way to look at how you build policy around big projects.”

“I feel there’s something of an obligation within NASA to look at this,” he added, “because it’s been around for so long and this idea hasn’t been destroyed yet. It’s persisted.”
Title: Re: Solar Power Satellites
Post by: Asteroza on 05/29/2022 10:05 pm
https://twitter.com/jeff_foust/status/1530179283360092165

Quote
At #ISDC2022 (Int’l Space Development Conference), Nikolai Joseph of NASA’s Office of Technology, Policy and Strategy said the office is starting a new study to revisit space-based solar power. Idea it to revisit existing proposals, updating technology, cost, policy issues.



Not many details about the study itself, which is scheduled to be completed and rolled out at IAC in September, but he said NASA will be updating existing proposed architectures for space-based solar, rather than developing new ones.

Would that be limited to previous NASA proposed architectures only? As a baseline, updating the old butterfly design is not unreasonable, but some new non-NASA ones have come out that would be interesting to flesh out a little. Though you can bet Mankins is going to busy trotting out SPS-ALPHA again.
Title: Re: Solar Power Satellites
Post by: su27k on 05/30/2022 03:40 am
Would that be limited to previous NASA proposed architectures only? As a baseline, updating the old butterfly design is not unreasonable, but some new non-NASA ones have come out that would be interesting to flesh out a little. Though you can bet Mankins is going to busy trotting out SPS-ALPHA again.

Sounds like it would be NASA proposed architecture only, basically update their old study to take into account recent developments such as launch cost. I think the idea is to see if this is feasible at all, if it is they can starting funding new architectures.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 05/30/2022 03:08 pm
Would that be limited to previous NASA proposed architectures only? As a baseline, updating the old butterfly design is not unreasonable, but some new non-NASA ones have come out that would be interesting to flesh out a little. Though you can bet Mankins is going to busy trotting out SPS-ALPHA again.

Sounds like it would be NASA proposed architecture only, basically update their old study to take into account recent developments such as launch cost. I think the idea is to see if this is feasible at all, if it is they can starting funding new architectures.
Lower cost for solar panels, etc, matter too. Not just for the competition but for actual orbital hardware costs. SpaceX, for instance, used basically commercial silicon solar cells for Dragon and early Starlink (don't know what they use now).

But I suspect looking at past studies will be inadequate to take this into account. A new, cost-engineered architecture is necessary.
Title: Re: Solar Power Satellites
Post by: Markstark on 05/30/2022 11:31 pm
https://spacenews.com/nasa-to-reexamine-space-based-solar-power/
Title: Re: Solar Power Satellites
Post by: Asteroza on 06/16/2022 11:50 pm
The chinese have built a test stand tower to simulate an end-to-end SPS system, with a pseudo-satellite collecting solar power, conversion to microwaves, then firing down about 50m to a rectenna. Tower allows swapping out the pseudo-sat and rectenna parts for easier testing. They achieved an initial full end-to-end demo with their first build so far, and plan to continue testing with various technology bits. Looks like the pseudo-sat uses an interesting parabolic mirror/PV config, but that may have been the easiest breadboard config to get started. Maybe they'll want to test a sandwich panel next?


https://news.xidian.edu.cn/info/2106/220926.htm (https://news.xidian.edu.cn/info/2106/220926.htm)
Title: Re: Solar Power Satellites
Post by: CameronD on 06/23/2022 02:26 am
Whilst travelling recently I noticed this one-pager in the latest Qantas (Australia) in-flight magazine.  Here's the first few paras - the full article is attached:
Quote
Melbourne architect Serdar Baycan's mission to build solar power generation satellites (SPS) is so out there that you might dismiss it as pie in the sky - until you realise that the UK government is already backing it. At the Space Summit, Australia's first astronaut, Paul Scully-Power, told the audience that the US, China and Russia are also on the move to get into space-based solar power.

"Conceptually, it's pretty simple - the sun always shines up there, it's got a lot of energy and will be around for a few billion years yet so let's get aboard," said Scully-Power, who is also a highly regarded expert in the private technology sector. "It's really going to happen."

Baycan has partnered with awardwinning former NASA physicist John Mankins to form an Australian company, Solar Space Technologies (SST), to develop and commercialise SPSs. "Space solar power will provide continuous, low-cost energy with zero carbon emissions for Australia and to export to the world," says Baycan. "As well as mitigating climate change, it will create thousands of well-paid jobs for Australians in urban and regional centres and partner countries."

https://www.solarspacetechnologies.com.au/

They make it sound sooo easy!  ::)
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 06/23/2022 10:44 am
Why would they build satellites in Australia, don't even have LV let alone large RLV.
Title: Re: Solar Power Satellites
Post by: SweetWater on 06/23/2022 11:28 am
Why would they build satellites in Australia, don't even have LV let alone large RLV.


Possibly they would be interested in developing the technology and then licensing it to others or partnering with another company for production and/or launch.

SPS is a long way off, and I would think there would be more short- and mid-term blue sky in developing traditional solar power in Australia, a country which has a lot of undeveloped land, a small population relative to that undeveloped land, and overall a relatively sunny climate.
Title: Re: Solar Power Satellites
Post by: su27k on 07/20/2022 12:41 pm
UK government invests £3 million in space-based solar power: https://www.gov.uk/government/news/intergalactic-investment-government-boosts-space-tech-funding-to-cut-carbon-emissions-and-improve-energy-security
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 07/20/2022 07:34 pm
UK government invests £3 million in space-based solar power: https://www.gov.uk/government/news/intergalactic-investment-government-boosts-space-tech-funding-to-cut-carbon-emissions-and-improve-energy-security
Not going build lot HW with £3m, but its a start as long as its used for HW development not reports.
Title: Re: Solar Power Satellites
Post by: su27k on 07/28/2022 05:30 am
https://twitter.com/Capoglou/status/1552392397480513537

Quote
⚡ @ESA has just released a new Request for Information for Breakthrough Technologies for Space-based Solar Power (#SBSP)👉🏻 https://lnkd.in/dk3Ev6_D



⚡️To prepare Europe for decision-making on a potential SBSP programme for Net Zero @ESA is proposing a SBSP preparatory programme for Europe named SOLARIS for the upcoming ESA Ministerial Council in November 2022 that addresses this imperative 👉🏻 https://lnkd.in/dk3Ev6_D



🌞#SOLARIS would be structured around the key development axes needed to establish the technical, political & programmatic basis of a decision on a European #SBSP development programme in 2025.  Also address potential challenges related to regulation & international space policy



#Solaris would undertake system-level studies & technology developments, in partnership with European industry, to mature the technical feasibility & assess benefits, implementation options, commercial opportunities, costs & risks of #SBSP.



Keep an eye here for more announcements next month. ESA is currently running two parallel industrial studies to assess the costs and benefits of SBSP for Europe as a whole. These studies will report by the end of summer 2022.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 08/16/2022 07:49 pm
Results of ESA studies, looks like they are going to invest more into SSP.
NB not read studies yet.

https://twitter.com/AschbacherJosef/status/1559553177598435328?t=yUhknLuHrxpyYbcKjoN2dA&amp;s=19
Title: Re: Solar Power Satellites
Post by: Asteroza on 08/16/2022 11:04 pm
Results of ESA studies, looks like they are going to invest more into SSP.
NB not read studies yet.

https://twitter.com/AschbacherJosef/status/1559553177598435328?t=yUhknLuHrxpyYbcKjoN2dA&amp;s=19


Superficially resembles the CASSIOPeiA  spinning windchime design, though functionally a folded brane aggregate of individual powersats
Title: Re: Solar Power Satellites
Post by: Comga on 08/16/2022 11:33 pm
Results of ESA studies, looks like they are going to invest more into SSP.
NB not read studies yet.

https://twitter.com/AschbacherJosef/status/1559553177598435328?t=yUhknLuHrxpyYbcKjoN2dA&amp;s=19 (https://twitter.com/AschbacherJosef/status/1559553177598435328?t=yUhknLuHrxpyYbcKjoN2dA&amp;s=19)


Superficially resembles the CASSIOPeiA  spinning windchime design, though functionally a folded brane aggregate of individual powersats

The CGI includes launching on a reusable ESA rocket with Falcon 9 style legs and fold-down gridfins but some form of vertical assembly.
Not particularly "near term"
Title: Re: Solar Power Satellites
Post by: SweetWater on 08/17/2022 12:00 am
The CGI includes launching on a reusable ESA rocket with Falcon 9 style legs and fold-down gridfins but some form of vertical assembly.
Not particularly "near term"

The not particularly near term part may be by design. This announcement has shades of Kennedy's 'We choose to go to the moon' speech in 1962; the reason the moon was chosen as a goal was that the US had been beaten by the Soviets to the first satellite and first human in space, and Kennedy needed a goal that was far enough out that the US might be able to catch up with and eventually beat the Soviets.

Europe has been largely left behind by other countries/launch providers when it comes to reuse, small launch, commercial launch, commercial human spaceflight, and satellite internet constellations, and it will probably be left behind in terms of commercial space stations. If Europe wants to get out ahead on anything they need to pick a long-term goal.

Space-based solar power isn't going to be practical for public power generation purposes for the foreseeable future - I wouldn't want to bet on a timeline, but Europe is no closer or farther away on this than anyone else. Yes, to make it practical they probably will need a heavy/super-heavy reusable launch vehicle, but that's hardly the long pole in this. Given enough investment, this is something they could conceivably get out in front of the rest of the world on. 
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 08/17/2022 12:45 am




Space-based solar power isn't going to be practical for public power generation purposes for the foreseeable future - I wouldn't want to bet on a timeline, but Europe is no closer or farther away on this than anyone else. Yes, to make it practical they probably will need a heavy/super-heavy reusable launch vehicle, but that's hardly the long pole in this. Given enough investment, this is something they could conceivably get out in front of the rest of the world on.

SSP is long way from being competitive with bulk power generation in western countries but need to start somewhere. We didn't go from first transatlantic flight to $500 seats overnight.

 
Title: Re: Solar Power Satellites
Post by: Asteroza on 08/17/2022 03:10 am
The CGI includes launching on a reusable ESA rocket with Falcon 9 style legs and fold-down gridfins but some form of vertical assembly.
Not particularly "near term"

Maiaspace is still touting a pretty aggressive dev schedule, but even that isn't fully reusable or heavy lift...
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 08/17/2022 03:15 am
The CGI includes launching on a reusable ESA rocket with Falcon 9 style legs and fold-down gridfins but some form of vertical assembly.
Not particularly "near term"

Maiaspace is still touting a pretty aggressive dev schedule, but even that isn't fully reusable or heavy lift...
NB this SSP thread not RLV.
Title: Re: Solar Power Satellites
Post by: Vultur on 08/17/2022 11:19 pm
For most places I can't see space solar being competitive with regular solar+battery storage, but for some European nations (really low insolation especially in winter) maybe.
Title: Re: Solar Power Satellites
Post by: DanClemmensen on 08/17/2022 11:33 pm
For most places I can't see space solar being competitive with regular solar+battery storage, but for some European nations (really low insolation especially in winter) maybe.
There, it must compete against long-distance transport of electricity via HVDC cables. An undersea HVDC cable is currently being run from Morocco to the UK to transport electricity from solar PV and wind. The Sahara is really big, and fairly close to Europe.
    https://electrek.co/2022/04/21/the-worlds-longest-subsea-cable-will-send-clean-energy-from-morocco-to-the-uk/
Title: Re: Solar Power Satellites
Post by: Vultur on 08/17/2022 11:51 pm
For most places I can't see space solar being competitive with regular solar+battery storage, but for some European nations (really low insolation especially in winter) maybe.
There, it must compete against long-distance transport of electricity via HVDC cables. An undersea HVDC cable is currently being run from Morocco to the UK to transport electricity from solar PV and wind. The Sahara is really big, and fairly close to Europe.
    https://electrek.co/2022/04/21/the-worlds-longest-subsea-cable-will-send-clean-energy-from-morocco-to-the-uk/
True, but that doesn't give energy independence. Depends on how certain they are of continued good relations with the sunnier nation.
Title: Re: Solar Power Satellites
Post by: Proponent on 08/18/2022 12:13 am
SSP is long way from being competitive with bulk power generation in western countries but need to start somewhere. We didn't go from first transatlantic flight to $500 seats overnight.

Unlike air transportation, however, SSP does not scale down well.
Title: Re: Solar Power Satellites
Post by: Asteroza on 08/18/2022 01:07 am
For most places I can't see space solar being competitive with regular solar+battery storage, but for some European nations (really low insolation especially in winter) maybe.
There, it must compete against long-distance transport of electricity via HVDC cables. An undersea HVDC cable is currently being run from Morocco to the UK to transport electricity from solar PV and wind. The Sahara is really big, and fairly close to Europe.
    https://electrek.co/2022/04/21/the-worlds-longest-subsea-cable-will-send-clean-energy-from-morocco-to-the-uk/

Jebus, is the Xlinks project real? It's like a mini-DESERTEC just for the UK, to snub the EU. Though it could also be a host to a SPS rectenna farm in Morocco if the UK is too NIMBY to put a 5km rectenna field somewhere north of London, I guess...

Though that brings up the point, that if the EU wants SPS for energy independence, where were they planning on hosting the rectenna fields? Finding a 5km circle that is open for rectenna install, that isn't too far from existing transmission infrastructure, that won't be crawling with NIMBY's is gonna be real interesting. Or were they planning on laser transmission to allow smaller receivers?
Title: Re: Solar Power Satellites
Post by: edzieba on 08/18/2022 11:05 am
For most places I can't see space solar being competitive with regular solar+battery storage, but for some European nations (really low insolation especially in winter) maybe.
There, it must compete against long-distance transport of electricity via HVDC cables. An undersea HVDC cable is currently being run from Morocco to the UK to transport electricity from solar PV and wind. The Sahara is really big, and fairly close to Europe.
    https://electrek.co/2022/04/21/the-worlds-longest-subsea-cable-will-send-clean-energy-from-morocco-to-the-uk/

Jebus, is the Xlinks project real? It's like a mini-DESERTEC just for the UK, to snub the EU. Though it could also be a host to a SPS rectenna farm in Morocco if the UK is too NIMBY to put a 5km rectenna field somewhere north of London, I guess...

Though that brings up the point, that if the EU wants SPS for energy independence, where were they planning on hosting the rectenna fields? Finding a 5km circle that is open for rectenna install, that isn't too far from existing transmission infrastructure, that won't be crawling with NIMBY's is gonna be real interesting. Or were they planning on laser transmission to allow smaller receivers?
Float them in the middle of lakes and reservoirs, or offshore for coastal areas. Nice big thermal sump for spillover energy, minimal sunlight obstruction more tolerable than for croplands, and don't get in the way of anyone other than recreational boaters (don't stick your rectennas outside of busy ports or in major shipping lanes).
Title: Re: Solar Power Satellites
Post by: Asteroza on 08/19/2022 03:19 am
For most places I can't see space solar being competitive with regular solar+battery storage, but for some European nations (really low insolation especially in winter) maybe.
There, it must compete against long-distance transport of electricity via HVDC cables. An undersea HVDC cable is currently being run from Morocco to the UK to transport electricity from solar PV and wind. The Sahara is really big, and fairly close to Europe.
    https://electrek.co/2022/04/21/the-worlds-longest-subsea-cable-will-send-clean-energy-from-morocco-to-the-uk/

Jebus, is the Xlinks project real? It's like a mini-DESERTEC just for the UK, to snub the EU. Though it could also be a host to a SPS rectenna farm in Morocco if the UK is too NIMBY to put a 5km rectenna field somewhere north of London, I guess...

Though that brings up the point, that if the EU wants SPS for energy independence, where were they planning on hosting the rectenna fields? Finding a 5km circle that is open for rectenna install, that isn't too far from existing transmission infrastructure, that won't be crawling with NIMBY's is gonna be real interesting. Or were they planning on laser transmission to allow smaller receivers?
Float them in the middle of lakes and reservoirs, or offshore for coastal areas. Nice big thermal sump for spillover energy, minimal sunlight obstruction more tolerable than for croplands, and don't get in the way of anyone other than recreational boaters (don't stick your rectennas outside of busy ports or in major shipping lanes).

5km+ diameter circular lakes are in short supply in the EU though. I don't think anybody has ever seriously proposed an independent floating rectenna farm for open ocean offshore. Most sea/coastal proposals are coral lagoons or in marsh/tidal flats that are uninhabited (but the greens will scream bloody murder) or a manmade island (rectenna on built land, but some more advanced ones are a closed dyke reservoir in the sea which is kept at a lower elevation, like a reverse pumped hydro plant, and somehow stringing up the rectenna over the depressed reservoir, but even those were avoiding floating rectennas). I believe the EU, either in the Netherlands or Belgium, were proposing building such a reverse hydro plant in the ocean (sometimes called low head seawater pumped hydro), as the sea is not too deep to make building the offshore dyke horrendously expensive.
Title: Re: Solar Power Satellites
Post by: su27k on 08/19/2022 05:15 am
https://spacenews.com/esa-to-request-funding-for-space-based-solar-power-study/

Quote
The Frazer-Nash study estimated that the net present value of a European SBSP system from 2022 to 2070 would range between 149 billion and 262 billion euros ($150–264 billion). A central case of 54 “gigawatt-class” SBSP satellites would produce 601 billion euros in benefits in that period, primarily from avoided costs of producing energy terrestrially along with its carbon dioxide emissions, with 418 billion euros in costs to develop and operate the SBSP system.

The Roland Berger study concluded that a single SBSP satellite, based on an existing design, could cost as little as 8.1 billion euros to build and 7.5 billion euros to operate for 30 years, assuming “substantial advances” in key technologies. In a worst-case scenario without those advances, the same design would cost 33.4 billion euros to build and 31.1 billion euros to operate. Despite the uncertainty, it concluded SBSP “has strong potential to become a competitive renewable technology.”
Title: Re: Solar Power Satellites
Post by: Asteroza on 08/19/2022 11:15 pm
ESA seems to be running their SPS stuff under the SOLARIS program name banner

https://www.esa.int/Enabling_Support/Space_Engineering_Technology/SOLARIS (https://www.esa.int/Enabling_Support/Space_Engineering_Technology/SOLARIS)

as a side development, ESA is starting a study program called PROTEIN for designing a new European Heavy Lift Launcher (EHLL), aiming for 10,000t a year to support SPS deployment, with EHLL possibly targeting 2035.

https://esastar-publication-ext.sso.esa.int/ESATenderActions/details/45216 (https://esastar-publication-ext.sso.esa.int/ESATenderActions/details/45216)
Title: Re: Solar Power Satellites
Post by: su27k on 08/20/2022 12:37 pm
https://twitter.com/DrPhiltill/status/1560657509215395846

Quote
I saw a bunch of Twitter criticism yesterday of ESA’s announcement that they want to develop tech for Space Based Solar Power. The criticism was not valid because it missed the entire point. Europe wants to move to 100% renewable energy — no dispatchable power for topping off. /1



2/ The closer you get to 100% renewable energy the more expensive it is to get the next percent. At close to 100% market penetration the cost is much higher than typical LCOE in today’s markets. This creates an economic space for a more expensive renewable that is baseload.



3/ You might ask, why not just use nuclear? Nuclear would be a great option, but for cultural and political reasons that is a non-starter in Europe 🤷‍♂️. Why not hydroelectric? Europe doesn’t have nearly enough hydro electric sites. There aren’t many options.



4/ So as long as Europe is committed to going 100% carbon-free — and they are — then SBSP fits the economic niche even though it will be more expensive than other energy sources.



5/ The situation for renewable energy in Europe is much worse than in the US due to Europe’s low capacity factor on wind and solar. The *combined* wind and solar averages about 15%. That’s for the entire continent.



6/ So the @elonmusk quote that ‘solar is only 3x better in space than on Earth’ is factually incorrect. For all of Europe Space is 6x better. And the cost is nonlinear so it is far more than 6x cost, especially when trying to get 100% market penetration, as Europe wants to do.



7/ Another major error critics make (repeatedly even after you explain their error), is they think space solar competes against terrestrial solar. It does not. It competes against terrestrial energy storage and excess generation capacity to recharge the deep storage.



8/ So the facile arguments comparing space vs terrestrial PV efficiency are missing the point. It’s a good idea never to believe facile arguments. The proponents of SBSP in Europe know all the facile arguments, and know why they aren’t valid. They aren’t stupid. I mean HONESTLY🤦‍♂️



9/ So you can get into arguments whether the cost estimates are accurate or whether the government subsidies will be economically justified or enough — that’s all good. That’s why ESA commissioned independent studies to augment their internal studies. The debate should continue.



10/ But drop the facile arguments that entirely miss the point, OK? And please don’t give them airtime because it promotes poor thinking. /end. We now return to the original happy programming 🚀🌖😉
Title: Re: Solar Power Satellites
Post by: libra on 08/20/2022 02:56 pm
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Life is full of surprises, really. Would never, ever have thought I would see SBSP been seriously considered in my lifetime.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 08/20/2022 09:24 pm
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Life is full of surprises, really. Would never, ever have thought I would see SBSP been seriously considered in my lifetime.
There are still lot technologies that need maturing before it becomes financially viable but not unrealistic with speed that commercial space is growing.
RLVs have a way to go but should see them mature fast over next decade. Early versions of robotic inspace assembly and manufacturing by end of decade.

There is still issue of transporting all that tonnage from LEO to GEO which is 3.8km/s. That requires lot of tanker launches and also puts lot of stress on RLV from high reentry velocities. The alternative is using lunar or asteriod ISRU fuel.

LEO to GEO leg can be done with SEP which will reduce fuel required but means travel time of few months. SSP component launches to LEO will be 2-3 times are week.
Title: Re: Solar Power Satellites
Post by: daedalus1 on 08/20/2022 09:35 pm
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Life is full of surprises, really. Would never, ever have thought I would see SBSP been seriously considered in my lifetime.

Really?
I've seen proposals and studies going back decades. They all come to nothing because launch costs are astronomical, whereas putting something in a field is zero cost.
Title: Re: Solar Power Satellites
Post by: edzieba on 08/22/2022 07:52 am
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Life is full of surprises, really. Would never, ever have thought I would see SBSP been seriously considered in my lifetime.

Really?
I've seen proposals and studies going back decades. They all come to nothing because launch costs are astronomical, whereas putting something in a field is zero cost.
That depends on the cost of your fields: not a lot of 'spare' land an Europe that is easy and cheap to construct on (or it would already have been).
Title: Solar Power Satellites
Post by: Star One on 08/22/2022 04:30 pm
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Life is full of surprises, really. Would never, ever have thought I would see SBSP been seriously considered in my lifetime.
The climate collapsing under your nose tends to focus minds. The massive drought across Europe makes that point.
Title: Re: Solar Power Satellites
Post by: libra on 08/22/2022 05:16 pm
Europe heats up 4 times faster than the rest of the northern hemisphere. I turned 40 the years Bordeaux went past 40°C, and this year was even worse - 41°C, 42°C, 43°C... southern Spain in the meantime has hit 48°C.

I once red: +1°C in the global climate, means Marocco / Spain climate cross into France by 150 km, direction the north. +2°C = 300 km... it's happening. Frack.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 08/22/2022 06:18 pm
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Life is full of surprises, really. Would never, ever have thought I would see SBSP been seriously considered in my lifetime.

Really?
I've seen proposals and studies going back decades. They all come to nothing because launch costs are astronomical, whereas putting something in a field is zero cost.
That depends on the cost of your fields: not a lot of 'spare' land an Europe that is easy and cheap to construct on (or it would already have been).
Can still grow crops under rectanna receivers, unlike solar.
Renewable take up far more land and don't provide steady base load 24/7 regards of weather? Existing base load generators are fossil fuel powered or Nuclear. Fusion is the only alternative to SSP, decades and 100s $B later still don't have working fusion power station.

SSP isn't just about reliable power but what spinoff technologies give us. Inspace assembly,  cheap launch by RLVs and ISRU to help build and lower cost of SSP.
At 50,000t per 1GW launching everything from   earth ain't going cut it for Terrawatts of generation needed. We need large industrial base inspace which will happen if market is there.

Currently 3/5 of our electricity generation is fossil fuels. By 2040 we need additional 30% more electricity generation, probably higher if most vehicle fleet move to EVs. Higher again if we replace a some of huge quantities of fossil fuels used for home and industrial heating.

Title: Re: Solar Power Satellites
Post by: Robotbeat on 08/22/2022 07:17 pm
The land use thing is really unimportant (as long as you’re not using biofuels), but it’ll take about an hour of dedicated arguing to prove it to anyone who doesn’t already think so (but is still open minded enough to change their mind) because it is such a commonly repeated meme.

Just look at the price of farmland per acre vs the cost of a solar array on that same land area and the amount of electricity revenue it generates from that area. AND that’s for farmland. Solar (or whatever) doesn’t have any need to use actual good farmland (unless also growing crops underneath, as is sometimes done), so they could get even cheaper prices. Dry land with crappy soil (or no soil) is fine and would be even cheaper.

The price of that farmland is far, far less than the price of the solar array. That just wouldn’t be true if land usage was such a huge constraint. (& there are lots of ways we could reduce farmland use if the land was really secretly super valuable, but we don’t bother because it’s not).

Again, I don’t expect any of you to be convinced because the meme has been repeated so often without actually doing this kind of comparative calculation.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 08/22/2022 07:18 pm
I still think we should try SBSP.
Title: Re: Solar Power Satellites
Post by: Welsh Dragon on 08/23/2022 09:18 am
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Life is full of surprises, really. Would never, ever have thought I would see SBSP been seriously considered in my lifetime.

Really?
I've seen proposals and studies going back decades. They all come to nothing because launch costs are astronomical, whereas putting something in a field is zero cost.
That depends on the cost of your fields: not a lot of 'spare' land an Europe that is easy and cheap to construct on (or it would already have been).
Can still grow crops under rectanna receivers, unlike solar.
Renewable take up far more land and don't provide steady base load 24/7 regards of weather? Existing base load generators are fossil fuel powered or Nuclear. Fusion is the only alternative to SSP, decades and 100s $B later still don't have working fusion power station.
Offshore wind would like a word. An average of 25% and up to 50% of UK power alone.
Title: Re: Solar Power Satellites
Post by: edzieba on 08/23/2022 09:44 am
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Life is full of surprises, really. Would never, ever have thought I would see SBSP been seriously considered in my lifetime.

Really?
I've seen proposals and studies going back decades. They all come to nothing because launch costs are astronomical, whereas putting something in a field is zero cost.
That depends on the cost of your fields: not a lot of 'spare' land an Europe that is easy and cheap to construct on (or it would already have been).
Can still grow crops under rectanna receivers, unlike solar.
Renewable take up far more land and don't provide steady base load 24/7 regards of weather? Existing base load generators are fossil fuel powered or Nuclear. Fusion is the only alternative to SSP, decades and 100s $B later still don't have working fusion power station.
Offshore wind would like a word. An average of 25% and up to 50% of UK power alone.
Does have the added pain of offshore infrastructure: needs to be cited in relatively shallow water (or spend $$$$$$$ on foundation work), all equipment needs to be able to survive in a marine environment, and inspection and maintenance has all the fun of working at height and of working offshore at the same time. NIMBY-resistant, but not a panacea and onshore wind of the same capacity will be cheaper to construct (with the assumption of dual-use land).

The 25% TWh/annum generated figure is for all UK wind power, not just offshore.
Title: Re: Solar Power Satellites
Post by: Welsh Dragon on 08/23/2022 09:59 am
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Life is full of surprises, really. Would never, ever have thought I would see SBSP been seriously considered in my lifetime.

Really?
I've seen proposals and studies going back decades. They all come to nothing because launch costs are astronomical, whereas putting something in a field is zero cost.
That depends on the cost of your fields: not a lot of 'spare' land an Europe that is easy and cheap to construct on (or it would already have been).
Can still grow crops under rectanna receivers, unlike solar.
Renewable take up far more land and don't provide steady base load 24/7 regards of weather? Existing base load generators are fossil fuel powered or Nuclear. Fusion is the only alternative to SSP, decades and 100s $B later still don't have working fusion power station.
Offshore wind would like a word. An average of 25% and up to 50% of UK power alone.
Does have the added pain of offshore infrastructure: needs to be cited in relatively shallow water (or spend $$$$$$$ on foundation work), all equipment needs to be able to survive in a marine environment, and inspection and maintenance has all the fun of working at height and of working offshore at the same time. NIMBY-resistant, but not a panacea and onshore wind of the same capacity will be cheaper to construct (with the assumption of dual-use land).

The 25% TWh/annum generated figure is for all UK wind power, not just offshore.
Don't disagree with any of that, but it doesn't take up land, which was the original point.
Title: Re: Solar Power Satellites
Post by: Genial Precis on 08/23/2022 01:34 pm
Robotbeat has the right of it. Four things are true:

1) Solar PV and wind have small demands for land compared to agriculture
2) They can use land that isn't suited for agriculture, such as desert.
3) They can use land simultaneously with agriculture
4) Agricultural productivity is growing faster than population, there is a lot of slop in agricultural land use in wealthy countries, and there is a lot of room for improvement of yields in poor countries with more capital, so that you could grow more food with less land even if 1-3 were not true.

It is overdetermined, by a lot, that land use is a nonissue for solar/wind. Contingent on obtaining better legal protection from NIMBYs there is no technical showstopper to depending heavily on them, and nuclear power is also contingent on protection from NIMBYs. There are no showstopper obstacles to strategies based on solar+wind+storage only, nuclear only, or all of the above, although solar+wind inclusive strategies will have much more nondispatchable capacity if you have anything useful to do with partially available but extremely cheap electricity.

I find arguments that selectively ignore pieces of the above to argue for one positive action while deriding others very tiresome and foolish. The NIMBYs are aligned. Don't divide your own coalition. There is no future without beating the NIMBYs, not with any technology because they oppose them all.

I support some exploration of SBSP, but as a bet, in the sense of "don't bet money you can't afford to lose", rather than something to count on. Which means it's no excuse to neglect practical energy policy.
Title: Re: Solar Power Satellites
Post by: Vultur on 08/23/2022 09:39 pm
I support some exploration of SBSP, but as a bet, in the sense of "don't bet money you can't afford to lose", rather than something to count on.

Yeah, I agree here. Worth looking into, but if it makes sense, it would be to go from "mostly renewable" to "all renewable"* in high latitude regions, or to provide
a domestic non-seasonal source of renewable energy in high latitude nations.

Assuming battery manufacturing can be sufficiently scaled up (not sure of the limits on that) earth solar+batteries is probably better in most places.

it should be studied, and perhaps demonstrated on a small scale, but not time to build it yet.

*though arguably it might work out better (in terms of carbon removal per money) to do offsets rather than get those last few percent... with offsets, Europe could remove carbon being emitted elsewhere, which might be more cost effective than going from 95% to 100% renewable

4) Agricultural productivity is growing faster than population

Is this still true? I know it's generally true averaged over say the last 75 years (since WWII) but is that still happening?
Even if so it may not remain true with increased extreme weather
Title: Re: Solar Power Satellites
Post by: Robotbeat on 08/24/2022 02:23 am
Robotbeat has the right of it. Four things are true:

1) Solar PV and wind have small demands for land compared to agriculture
2) They can use land that isn't suited for agriculture, such as desert.
3) They can use land simultaneously with agriculture
4) Agricultural productivity is growing faster than population, there is a lot of slop in agricultural land use in wealthy countries, and there is a lot of room for improvement of yields in poor countries with more capital, so that you could grow more food with less land even if 1-3 were not true.

It is overdetermined, by a lot, that land use is a nonissue for solar/wind. Contingent on obtaining better legal protection from NIMBYs there is no technical showstopper to depending heavily on them, and nuclear power is also contingent on protection from NIMBYs. There are no showstopper obstacles to strategies based on solar+wind+storage only, nuclear only, or all of the above, although solar+wind inclusive strategies will have much more nondispatchable capacity if you have anything useful to do with partially available but extremely cheap electricity.

I find arguments that selectively ignore pieces of the above to argue for one positive action while deriding others very tiresome and foolish. The NIMBYs are aligned. Don't divide your own coalition. There is no future without beating the NIMBYs, not with any technology because they oppose them all.

I support some exploration of SBSP, but as a bet, in the sense of "don't bet money you can't afford to lose", rather than something to count on. Which means it's no excuse to neglect practical energy policy.
*PRECISELY*
Title: Re: Solar Power Satellites
Post by: Robotbeat on 08/24/2022 02:41 am
I support some exploration of SBSP, but as a bet, in the sense of "don't bet money you can't afford to lose", rather than something to count on.

Yeah, I agree here. Worth looking into, but if it makes sense, it would be to go from "mostly renewable" to "all renewable"* in high latitude regions, or to provide
a domestic non-seasonal source of renewable energy in high latitude nations.

Assuming battery manufacturing can be sufficiently scaled up (not sure of the limits on that) earth solar+batteries is probably better in most places.

it should be studied, and perhaps demonstrated on a small scale, but not time to build it yet.

*though arguably it might work out better (in terms of carbon removal per money) to do offsets rather than get those last few percent... with offsets, Europe could remove carbon being emitted elsewhere, which might be more cost effective than going from 95% to 100% renewable

4) Agricultural productivity is growing faster than population

Is this still true? I know it's generally true averaged over say the last 75 years (since WWII) but is that still happening?
Even if so it may not remain true with increased extreme weather
Yes, it seems to be true. Data is consistent at least through 2019 in the US and given usual statistical variances. The US is a western country, so has much less catch-up growth in agricultural productivity while our population increase is slowing (as we restrict immigration while our fertility rate falls AND our life expectancy falls/stagnates). I think it's reasonable to suggest this will be true in 3rd world countries as well, as their fertility rate is falling dramatically as they develop.

(I just mashed up two graphs, with the red squares being US population and the other stuff being corn yield per acre. Both graphs start at 0 on the bottom, and I adjusted the scale of the population graph so that both datasets lined up roughly at 1950. Corn yields seem to be continuing their upward growth, but you can see US population growth starting to stagnate.)
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 08/24/2022 02:41 am
I support some exploration of SBSP, but as a bet, in the sense of "don't bet money you can't afford to lose", rather than something to count on.

Yeah, I agree here. Worth looking into, but if it makes sense, it would be to go from "mostly renewable" to "all renewable"* in high latitude regions, or to provide
a domestic non-seasonal source of renewable energy in high latitude nations.

Assuming battery manufacturing can be sufficiently scaled up (not sure of the limits on that) earth solar+batteries is probably better in most places.

it should be studied, and perhaps demonstrated on a small scale, but not time to build it yet.

*though arguably it might work out better (in terms of carbon removal per money) to do offsets rather than get those last few percent... with offsets, Europe could remove carbon being emitted elsewhere, which might be more cost effective than going from 95% to 100% renewable

4) Agricultural productivity is growing faster than population

Is this still true? I know it's generally true averaged over say the last 75 years (since WWII) but is that still happening?
Even if so it may not remain true with increased extreme weather
A pilot system of few MWs would be great place to start. Going cost fortune but should prove out technology one way or another.
Title: Re: Solar Power Satellites
Post by: su27k on 10/06/2022 03:16 am
Pretty good overview article: Space-based solar power: could beaming sunlight back to Earth meet our energy needs? (https://physicsworld.com/a/space-based-solar-power-could-beaming-sunlight-back-to-earth-meet-our-energy-needs/)

Quote from: physicsworld.com
The notion of capturing sunlight in space and beaming it to Earth has long been the stuff of science fiction. But as Jon Cartwright discovers, governments around the world are now taking “space-based solar power” seriously as a potential solution to our energy needs
Title: Re: Solar Power Satellites
Post by: Asteroza on 10/06/2022 03:58 am
Pretty good overview article: Space-based solar power: could beaming sunlight back to Earth meet our energy needs? (https://physicsworld.com/a/space-based-solar-power-could-beaming-sunlight-back-to-earth-meet-our-energy-needs/)

Quote from: physicsworld.com
The notion of capturing sunlight in space and beaming it to Earth has long been the stuff of science fiction. But as Jon Cartwright discovers, governments around the world are now taking “space-based solar power” seriously as a potential solution to our energy needs

Article had an interesting newer variation pic of SPS-Alpha

The UK consortium working on a 12 year plan for SPS

https://spaceenergyinitiative.org.uk/ (https://spaceenergyinitiative.org.uk/)


Ian Cash and the CASSIOPeiA design (a descendant of his earlier HESPeruS design)

https://www.internationalelectric.com/ (https://www.internationalelectric.com/)

The bit about the chinese working on the MR-SPS, a multi rotary joint design that tries to brute force the rotary joint vacuum electric arcing problem by splitting the difference, didn't mention another chinese design, the SSPS-OMEGA

https://www.sciencedirect.com/science/article/abs/pii/S0094576515300680 (https://www.sciencedirect.com/science/article/abs/pii/S0094576515300680)

Title: Re: Solar Power Satellites
Post by: lamontagne on 10/07/2022 01:39 pm
So the real fundamental competition to solar power satellites if good and cheap recyclable batteries?  If these exist solar power satellites are not cost effective?
Title: Re: Solar Power Satellites
Post by: edzieba on 10/07/2022 03:54 pm
So the real fundamental competition to solar power satellites if good and cheap recyclable batteries?  If these exist solar power satellites are not cost effective?
Depends on what you want your SPS for. If you want to roll an antenna into place in the middle of nowhere (or after a disaster that has damaged local infrastructure) and have access to several MW immediately, then battery buffers are of no value.
Or as an emergency diesel generator alternative: no emissions, no ongoing maintenance (other than keeping pigeons form nesting in the idle receiver), takes up some amount of roof area (with a sparse array, possibly just installed over top of part of a solar array).
Not all power generating methods need to be directly price-competitive with minimum baseload generation.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/07/2022 04:35 pm
So the real fundamental competition to solar power satellites if good and cheap recyclable batteries?  If these exist solar power satellites are not cost effective?
First generation stations won't be cost competitive with terrestrial alternative same as early solar and wind weren't. Build a few and costs will drop dramatically.

High demand for launch will drive prices down. Given enough demand and potential demand then sourcing some materials from moon along with fuel becomes viable.

World needs a few TWs of generation over next few decades. Assume 250W per Kg and that is 4,000,000t a TW.

Title: Re: Solar Power Satellites
Post by: lamontagne on 10/07/2022 05:26 pm
So the real fundamental competition to solar power satellites if good and cheap recyclable batteries?  If these exist solar power satellites are not cost effective?
First generation stations won't be cost competitive with terrestrial alternative same as early solar and wind weren't. Build a few and costs will drop dramatically.

High demand for launch will drive prices down. Given enough demand and potential demand then sourcing some materials from moon along with fuel becomes viable.

World needs a few TWs of generation over next few decades. Assume 250W per Kg and that is 4,000,000t a TW.

Is that 250 W/kg the power density of the batteries?  Because the world has way over one billion cars, all of which will be replaced eventually.  So just there you get 500 000 000 t of storage, at 500 kg per car.  I put the world energy requirements to replace everything else at about 10 TW.  So you have 40 000 000 t of storage for one hour.  All those cars can cover about 20 hours.  You would want a fair amount of backup so perhaps one billion tonnes would be good enough?

I have a few calculations on that, joined.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/07/2022 08:24 pm


So the real fundamental competition to solar power satellites if good and cheap recyclable batteries?  If these exist solar power satellites are not cost effective?
First generation stations won't be cost competitive with terrestrial alternative same as early solar and wind weren't. Build a few and costs will drop dramatically.

High demand for launch will drive prices down. Given enough demand and potential demand then sourcing some materials from moon along with fuel becomes viable.

World needs a few TWs of generation over next few decades. Assume 250W per Kg and that is 4,000,000t a TW.

Is that 250 W/kg the power density of the batteries?  Because the world has way over one billion cars, all of which will be replaced eventually.  So just there you get 500 000 000 t of storage, at 500 kg per car.  I put the world energy requirements to replace everything else at about 10 TW.  So you have 40 000 000 t of storage for one hour.  All those cars can cover about 20 hours.  You would want a fair amount of backup so perhaps one billion tonnes would be good enough?

I have a few calculations on that, joined.

Best satellite panels are 165wkg but they need to fold up and structure survive launch

GigaWatt arrays will be assembled in space and structure ultra light as it lives in 0g.


Title: Re: Solar Power Satellites
Post by: Asteroza on 10/10/2022 05:52 am
Emrod is back with a joint press release with Airbus and ESA regarding improvements in power beaming, applicable to SPS

https://emrod.energy/press-release-emrod-successfully-demonstrates-power-beaming-technology-to-unlock-space-based-solar-power/ (https://emrod.energy/press-release-emrod-successfully-demonstrates-power-beaming-technology-to-unlock-space-based-solar-power/)

https://emrod.energy/emrod-partners-with-airbus-and-the-european-space-agency-for-demonstration/ (https://emrod.energy/emrod-partners-with-airbus-and-the-european-space-agency-for-demonstration/)


They also seem to think their technology may be applicable to applying receiver surfaces on aircraft, to potentially allow SPS to power flying electric aircraft.

Title: Re: Solar Power Satellites
Post by: Star One on 10/10/2022 09:31 am
Pretty good overview article: Space-based solar power: could beaming sunlight back to Earth meet our energy needs? (https://physicsworld.com/a/space-based-solar-power-could-beaming-sunlight-back-to-earth-meet-our-energy-needs/)

Quote from: physicsworld.com
The notion of capturing sunlight in space and beaming it to Earth has long been the stuff of science fiction. But as Jon Cartwright discovers, governments around the world are now taking “space-based solar power” seriously as a potential solution to our energy needs
Frustrating to read that conspiracy minded thinking of some in society maybe a barrier to this technology. Seen first hand recently how much problem this can cause in populations with the Covid vaccination roll out.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/10/2022 10:17 am
Emrod is back with a joint press release with Airbus and ESA regarding improvements in power beaming, applicable to SPS

https://emrod.energy/press-release-emrod-successfully-demonstrates-power-beaming-technology-to-unlock-space-based-solar-power/ (https://emrod.energy/press-release-emrod-successfully-demonstrates-power-beaming-technology-to-unlock-space-based-solar-power/)

https://emrod.energy/emrod-partners-with-airbus-and-the-european-space-agency-for-demonstration/ (https://emrod.energy/emrod-partners-with-airbus-and-the-european-space-agency-for-demonstration/)


They also seem to think their technology may be applicable to applying receiver surfaces on aircraft, to potentially allow SPS to power flying electric aircraft.
"
Held at Airbus’ Munich Area Site, Emrod’s indoor demonstration system wirelessly beamed power over 36m at a frequency of 5.8GHz, using a square phased-array transmitting antenna of 1.92m in diameter and a similarly sized receiving antenna
"

36m isn't much of a demonstration.
Title: Re: Solar Power Satellites
Post by: CameronD on 10/10/2022 10:25 pm
"Held at Airbus’ Munich Area Site, Emrod’s indoor demonstration system wirelessly beamed power over 36m at a frequency of 5.8GHz, using a square phased-array transmitting antenna of 1.92m in diameter and a similarly sized receiving antenna
"

36m isn't much of a demonstration.

Of more interest would be the losses: presumably non-zero but hopefully a precise "36" meters doesn't mean they were 100%!
Title: Re: Solar Power Satellites
Post by: Asteroza on 10/10/2022 11:23 pm
Emrod is back with a joint press release with Airbus and ESA regarding improvements in power beaming, applicable to SPS

https://emrod.energy/press-release-emrod-successfully-demonstrates-power-beaming-technology-to-unlock-space-based-solar-power/ (https://emrod.energy/press-release-emrod-successfully-demonstrates-power-beaming-technology-to-unlock-space-based-solar-power/)

https://emrod.energy/emrod-partners-with-airbus-and-the-european-space-agency-for-demonstration/ (https://emrod.energy/emrod-partners-with-airbus-and-the-european-space-agency-for-demonstration/)


They also seem to think their technology may be applicable to applying receiver surfaces on aircraft, to potentially allow SPS to power flying electric aircraft.
"
Held at Airbus’ Munich Area Site, Emrod’s indoor demonstration system wirelessly beamed power over 36m at a frequency of 5.8GHz, using a square phased-array transmitting antenna of 1.92m in diameter and a similarly sized receiving antenna
"

36m isn't much of a demonstration.

"Held at Airbus’ Munich Area Site, Emrod’s indoor demonstration system wirelessly beamed power over 36m at a frequency of 5.8GHz, using a square phased-array transmitting antenna of 1.92m in diameter and a similarly sized receiving antenna
"

36m isn't much of a demonstration.

Of more interest would be the losses: presumably non-zero but hopefully a precise "36" meters doesn't mean they were 100%!

They have a 200m test site and the power company demo is supposedly going to 2km at first. The big point is claiming 96% efficiency, with a path to 99%, due to some sort of extended near field tricks. Which I suppose works out when the receiver is still small and fancy, but scale up costs may still make it lose compared to a traditional wire mesh rectenna.
Title: Re: Solar Power Satellites
Post by: Tywin on 10/11/2022 03:26 pm
This company could revolutionize the game...

https://solestial.com/

https://spacenews.com/solestial-seed-round/

Quote
Even including this efficiency penalty, Solestial panels reduce the cost of solar by 90% vs. traditional III-V panels.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 10/11/2022 03:32 pm
It’s worth pointing out that SpaceX spends probably even less than that on their Starlink solar panels.
Title: Re: Solar Power Satellites
Post by: alexterrell on 10/11/2022 03:51 pm
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Europe makes sense for an initial market as it has high latitudes and large demand for clean energy. Above about 50 degrees North, terrestrial solar is pretty useless in the winter.

I could see a solution where a power sat beams to the North Sea from September to March, and to Argentina or southern Australia from April to August.
Title: Re: Solar Power Satellites
Post by: Tywin on 10/11/2022 03:55 pm
It’s worth pointing out that SpaceX spends probably even less than that on their Starlink solar panels.

Source?
Title: Re: Solar Power Satellites
Post by: alexterrell on 10/11/2022 03:59 pm
The land use thing is really unimportant (as long as you’re not using biofuels), but it’ll take about an hour of dedicated arguing to prove it to anyone who doesn’t already think so
Actually it is important because there is an inherent belief that farm land should be used for farming.
Example: https://www.theguardian.com/environment/2022/oct/10/ministers-hope-to-ban-solar-projects-from-most-english-farms

That will probably persist even if we have Solar Foods (https://solarfoods.com/) making food out of solar power.

The belief is quite strong in Italy, where there is a romantic attachment to the land.

I think a solution will be to put 100GW "farms" in the Adriatic and Aegean seas.

Likewise, if we want 5km diameter rectennas, we can put those in the Thames Estuary or similar places.

Title: Re: Solar Power Satellites
Post by: RedLineTrain on 10/11/2022 03:59 pm
https://spacenews.com/nasa-to-reexamine-space-based-solar-power/

From that May article...

Quote
The goal is to finish the study and present it at the International Astronautical Congress in Paris in September.

Was the study finished and presented at IAC?
Title: Re: Solar Power Satellites
Post by: Tywin on 10/11/2022 04:03 pm
https://twitter.com/Capoglou/status/1579823532586176513
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/11/2022 07:50 pm
The land use thing is really unimportant (as long as you’re not using biofuels), but it’ll take about an hour of dedicated arguing to prove it to anyone who doesn’t already think so
Actually it is important because there is an inherent belief that farm land should be used for farming.
Example: https://www.theguardian.com/environment/2022/oct/10/ministers-hope-to-ban-solar-projects-from-most-english-farms

That will probably persist even if we have Solar Foods (https://solarfoods.com/) making food out of solar power.

The belief is quite strong in Italy, where there is a romantic attachment to the land.

I think a solution will be to put 100GW "farms" in the Adriatic and Aegean seas.

Likewise, if we want 5km diameter rectennas, we can put those in the Thames Estuary or similar places.
Can and most likely would be crop farm under the receiver.

Using that power to grow indoor crops 365 days of year would be far more productive use of the land. The other benefits is more secure food supply that isn't vulnerable to fickle weather patterns. Also makes country's food production more self sufficient.
These reasons alone could justify higher energy costs.



Title: Re: Solar Power Satellites
Post by: Asteroza on 10/11/2022 11:02 pm
The land use thing is really unimportant (as long as you’re not using biofuels), but it’ll take about an hour of dedicated arguing to prove it to anyone who doesn’t already think so
Actually it is important because there is an inherent belief that farm land should be used for farming.
Example: https://www.theguardian.com/environment/2022/oct/10/ministers-hope-to-ban-solar-projects-from-most-english-farms

That will probably persist even if we have Solar Foods (https://solarfoods.com/) making food out of solar power.

The belief is quite strong in Italy, where there is a romantic attachment to the land.

I think a solution will be to put 100GW "farms" in the Adriatic and Aegean seas.

Likewise, if we want 5km diameter rectennas, we can put those in the Thames Estuary or similar places.
Can and most likely would be crop farm under the receiver.

Using that power to grow indoor crops 365 days of year would be far more productive use of the land. The other benefits is more secure food supply that isn't vulnerable to fickle weather patterns. Also makes country's food production more self sufficient.
These reasons alone could justify higher energy costs.

If productivity was the primary measure, we would all be eating more quorn from bioreactors rather than proper vegetables.

Still, that's an interesting point, in so much that as the demographics change to more senior people, the need for specialist foods increases. Former clean rooms are being used to manufacture low/no potassium vegetables via indoor 365 farming (sometimes hydroponically) for people with dietary restrictions currently, and that market is expanding beyond hospitals and care homes.

There could also be a case made for other kinds of specialist/niche food. A recent twitter thread I had read was talking about the stereotypical image of british food being bland, but that is actually a symptom of other macro-economic issues, as older british foods had quite a variety and inventiveness, but loss of local land access due to estate fencing reduced the number of enacted recipes from lack of ingredient access, and the rationing post world war 2 effectively killed off the institutional/generation memory as recipes weren't being practiced. Resurrecting those niche ingredients (which were previously foraged) for production would result in a very weird intersection of solar power advocates. indoor agriculture researchers, and culinary historians. If you could get the government to fund it under cultural preservation mandates, all the better.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/11/2022 11:53 pm
World is just one large volcanic eruption from food crisis. Europe has had few mass starvations due to loss of 1-2 summer growing seasons. Its not matter of if but when next eruption will happen.

Growing staple food crops is long way from being economical but given choice between cost and starvation.

https://krishi.outlookindia.com/story/wheat-may-be-grown-indoors-but-the-cost/381382
Title: Re: Solar Power Satellites
Post by: Lampyridae on 10/12/2022 09:08 am
The land use thing is really unimportant (as long as you’re not using biofuels), but it’ll take about an hour of dedicated arguing to prove it to anyone who doesn’t already think so
Actually it is important because there is an inherent belief that farm land should be used for farming.
Example: https://www.theguardian.com/environment/2022/oct/10/ministers-hope-to-ban-solar-projects-from-most-english-farms

That will probably persist even if we have Solar Foods (https://solarfoods.com/) making food out of solar power.

The belief is quite strong in Italy, where there is a romantic attachment to the land.

I think a solution will be to put 100GW "farms" in the Adriatic and Aegean seas.

Likewise, if we want 5km diameter rectennas, we can put those in the Thames Estuary or similar places.
Can and most likely would be crop farm under the receiver.

Using that power to grow indoor crops 365 days of year would be far more productive use of the land. The other benefits is more secure food supply that isn't vulnerable to fickle weather patterns. Also makes country's food production more self sufficient.
These reasons alone could justify higher energy costs.

Would be interesting to see the cost-benefit analysis of a greenhouse material that warms and fluoresces under microwave irradiation. Some quantum dot materials already convert excess UV (which plants don't really use) and turn that into photosynthesis-friendly bands of light like orange. (Or just go the wire-mesh route and string some LEDs underneath the mesh canopy)

On-topic: TheRadicalModerate made a good point about peaking power. Hell, you could probably build rectennas into solar farms. Use the same DC conversion system. Peak power output is much more expensive because you are tapping gas turbines, pumped storage etc to cope with the extra demand, and that's where SBSP can step in.

Say you have an SBSP satellite over the Atlantic, beaming to Europe, say France because it's more central. It does so from 18:00 to midnight, Central European Time (ie Paris). That corresponds to a block of six hours, and it coincides with peak energy demand. At 0:00 CET, it's 18:00 in Washington. The satellite feeds the East Coast grid for six hours. Then it effectively twiddles its thumbs for 12 hours, selling daytime power to Europe, the Americas and Africa as needed.

But with agile beam steering, there's no need to stick to a geostationary equatorial orbit, or even a 24-hour one. Demand peaks for about 6 hours, so you could probably design a highly inclined orbit that arranges to be over the poles and providing on-demand power to a whole continent while it's in the night period.

You could also make it elliptical, and coming in low and fast over the Southern Hemisphere (not a huge energy market). They could benefit from smaller rectenna farms and get a burst of power on the cheap. At apogee, your footprint is larger than the market's standard rectenna size and then you have a maintenance period for an hour or so while you retarget the next customer. With an elliptical 12-hour or 8-hour orbit, the apogee is still lower than GEO, and your footprint is smaller.
Title: Re: Solar Power Satellites
Post by: Lampyridae on 10/12/2022 09:21 am
There could also be a case made for other kinds of specialist/niche food. A recent twitter thread I had read was talking about the stereotypical image of british food being bland, but that is actually a symptom of other macro-economic issues, as older british foods had quite a variety and inventiveness, but loss of local land access due to estate fencing reduced the number of enacted recipes from lack of ingredient access, and the rationing post world war 2 effectively killed off the institutional/generation memory as recipes weren't being practiced. Resurrecting those niche ingredients (which were previously foraged) for production would result in a very weird intersection of solar power advocates. indoor agriculture researchers, and culinary historians. If you could get the government to fund it under cultural preservation mandates, all the better.

It is quite bizarre how rapidly food habits change. Not even half a century after WWII, this sushi food from Japan shows up. Raw fish! Wrapped in seaweed! Who would eat that? Oh, it's actually quite clever! What an exotic food! Well, that's exactly what people on the British coasts actually ate before rationing, as you say, killed off the institutional memory. Dulce, a red seaweed, used to be a wildly popular snack because it tastes like bacon. Charles Dickens wrote about it.

Now it's time to forget about luxuries such as sushi and for us to learn to love eating ze bugs.
Title: Re: Solar Power Satellites
Post by: CameronD on 10/13/2022 12:24 am
Wait, this mean that all of sudden, SBSP makes some sense - even if only for Europe, and only on a niche ?

Europe makes sense for an initial market as it has high latitudes and large demand for clean energy. Above about 50 degrees North, terrestrial solar is pretty useless in the winter.

I could see a solution where a power sat beams to the North Sea from September to March, and to Argentina or southern Australia from April to August.

If you're going to do that, why not dispense with the power sat and put up a mirror instead?  Sunlight focussed on your solar farm all year round!  Interestingly enough, even though proposed as a solution way back in the 70's (or perhaps earlier) space mirrors aren't yet a thing either.  Probably for many of the same reasons we have yet to see a power sat in orbit.
 
Title: Re: Solar Power Satellites
Post by: Asteroza on 10/13/2022 02:43 am
Would be interesting to see the cost-benefit analysis of a greenhouse material that warms and fluoresces under microwave irradiation. Some quantum dot materials already convert excess UV (which plants don't really use) and turn that into photosynthesis-friendly bands of light like orange. (Or just go the wire-mesh route and string some LEDs underneath the mesh canopy)

On-topic: TheRadicalModerate made a good point about peaking power. Hell, you could probably build rectennas into solar farms. Use the same DC conversion system. Peak power output is much more expensive because you are tapping gas turbines, pumped storage etc to cope with the extra demand, and that's where SBSP can step in.

Say you have an SBSP satellite over the Atlantic, beaming to Europe, say France because it's more central. It does so from 18:00 to midnight, Central European Time (ie Paris). That corresponds to a block of six hours, and it coincides with peak energy demand. At 0:00 CET, it's 18:00 in Washington. The satellite feeds the East Coast grid for six hours. Then it effectively twiddles its thumbs for 12 hours, selling daytime power to Europe, the Americas and Africa as needed.

But with agile beam steering, there's no need to stick to a geostationary equatorial orbit, or even a 24-hour one. Demand peaks for about 6 hours, so you could probably design a highly inclined orbit that arranges to be over the poles and providing on-demand power to a whole continent while it's in the night period.

You could also make it elliptical, and coming in low and fast over the Southern Hemisphere (not a huge energy market). They could benefit from smaller rectenna farms and get a burst of power on the cheap. At apogee, your footprint is larger than the market's standard rectenna size and then you have a maintenance period for an hour or so while you retarget the next customer. With an elliptical 12-hour or 8-hour orbit, the apogee is still lower than GEO, and your footprint is smaller.

Cassiopeia was talking about utilizing non-GEO orbits. Tundra/Molynia orbits might be candidates at first glance, but the high apogee imposes the same distance problems as GEO for the target region, if relying on the apogee dwell. If not, then other suitable MEO styles exist that match the capabilities of a highly active steerable phased array but there would be a whole lot of constellation tweaking to match up to customer regions better.
Title: Re: Solar Power Satellites
Post by: Lampyridae on 10/13/2022 03:10 pm
Cassiopeia was talking about utilizing non-GEO orbits. Tundra/Molynia orbits might be candidates at first glance, but the high apogee imposes the same distance problems as GEO for the target region, if relying on the apogee dwell. If not, then other suitable MEO styles exist that match the capabilities of a highly active steerable phased array but there would be a whole lot of constellation tweaking to match up to customer regions better.

Ha, look at me, foolishly reinventing the wheel. This is basically what SICA Designs was saying near the start of the thread. The Cassiopeia design is really smart - and pretty cool-looking to boot. I must try and get that article from them.
Title: Re: Solar Power Satellites
Post by: su27k on 10/15/2022 12:48 pm
https://twitter.com/jeff_foust/status/1580649793634045953

Quote
NASA’s Bhavya Lal says the space-based solar power study her Office of Technology, Policy, and Strategy has been performing is going through the review process; plan to make it public once that is complete.
Title: Re: Solar Power Satellites
Post by: Asteroza on 10/20/2022 04:58 am
Slight update from Caltech on their SPS tile efforts, including a target of a space orbital demo in december of 2022?

https://www.caltech.edu/about/news/space-solar-power-atwater-hajimiri-pellegrino (https://www.caltech.edu/about/news/space-solar-power-atwater-hajimiri-pellegrino)


Apparently they disclosed last year a $100 million donation from 2013 for SPS work
https://www.caltech.edu/about/news/caltech-announces-breakthrough-100-million-gift-to-fund-space-based-solar-power-project (https://www.caltech.edu/about/news/caltech-announces-breakthrough-100-million-gift-to-fund-space-based-solar-power-project)
Title: Re: Solar Power Satellites
Post by: su27k on 10/21/2022 01:10 pm
Another overview article from Science, focused on recent development: Space-based solar power is getting serious—can it solve Earth’s energy woes? (https://www.science.org/content/article/space-based-solar-power-getting-serious-can-it-solve-earth-s-energy-woes)

Quote
Late last month in Munich, engineers at the European aerospace firm Airbus showed off what might be the future of clean energy. They collected sunlight with solar panels, transformed it into microwaves, and beamed the energy across an aircraft hangar, where it was turned back to electricity that, among other things, lit up a model of a city. The demo delivered just 2 kilowatts over 36 meters, but it raised a serious question: Is it time to resurrect a scheme long derided as science fiction and launch giant satellites to collect solar energy in space? In a high orbit, liberated from clouds and nighttime, they could generate power 24 hours a day and beam it down to Earth.

“It’s not new science, it’s an engineering problem,” says Airbus engineer Jean-Dominique Coste. “But it’s never been done at [large] scale.”

The urgent need for green energy, cheaper access to space, and improvements in technology could finally change that, proponents of space solar power believe. “Once someone makes the commercial investment, it will bloom. It could be a trillion-dollar industry,” says former NASA researcher John Mankins, who evaluated space solar power for the agency a decade ago.
Title: Re: Solar Power Satellites
Post by: su27k on 10/21/2022 01:14 pm
https://twitter.com/DrPhiltill/status/1583106346538311680

Quote
This is article is a good overview of current thinking on SBSP. I will add a little about how I was changed from skepticism to cautious optimism to actual optimism. A short 🧵/1



2/ Maybe 20 years ago I was skeptical simply because I was always skeptical of every idea and especially those which come from enthusiasts, since enthusiasts are more likely to suffer cognitive bias. I was careful to *never* suggest that SBSP may be a benefit of space. But…



3/ …the skepticism of another skeptic shook me out of that funk because I could see he went too far. It was Pete Worden, former head of Reagan’s Star Wars program and later head of NASA Ames. Pete was never known for technological timidity, and yet he was a disbeliever in SBSP.



4/ But one time I heard him give a talk where he said that SBSP is too expensive by five orders of magnitude (100,000x more costly) compared to putting solar on the ground — e.g., by coating a desert with PV to supply national or regional energy needs. So I checked his numbers…



5/ It turns out he made a basic mistake, one which most skeptics of SBSP still routinely make. He was comparing the cost of SBSP, which is 24/7 100% market penetration baseload power, vs PV without storage or a smart grid to turn it into baseload, at ~30% market penetration.



6/ And he was using Space Shuttle or similar launch costs since newer heavy lifts were not available back then. And he was assuming no technological progress in SBSP. When you correct those, you get to within an order of magnitude of terrestrial renewables, where the latter…



7/ …are still at less than 100% market penetration — which is really hard and costly with renewables since they are mostly intermittent. (Exceptions like hydro are geographically limited and power-limited.) So if we are within 1-2 orders of magnitude, then maybe it is possible.



8/ So about 15 years ago I began to argue that SBSP is still not economically viable until after we have a full industrial supply chain operating outside Earth’s gravity well, but then it should become viable. That still pushes SBSP decades into the future.



9/ Then I was part of a very large proposal team for a gargantuan project (that was surprisingly *almost* funded) to directly work on that off-Earth supply chain with the goal of making SBSP viable. I worked with pro-SBSP John Mankins on that team, and got to hear his arguments.



10/ Mankins argues for hyper-modularity of the system so that large reductions in manufacturing cost can occur. If 90% of the mass consists of a small number of low-cost, easily manufactured modules, then we may get a 1-2 order of magnitude cost reduction, easily.



11/ About 4 years ago I was at a conference luncheon where Mankins was the speaker. He argued that SBSP is economically viable. Pete Worden was in the audience. After the talk, Worden immediately raised his hand and said, “I think you have convinced me.”



12/ Mankins was (and is) arguing for a version of SBSP where we don’t have to wait for off-Earth industry. The story only gets better as we add off-Earth industry. I gave a talk on this at @esa’s recent workshop.



13/ When we have lunar propellant manufacturing, the cost of boosting SBSP from LEO to GEO is cheaper. I know there are skeptics of that, too, but I have a paper that proves it currently in peer review. I will share that ASAP.



14/ Another early application of space resources for SBSP could be structural elements. That is only about 20% of the mass, so it may be a real business opportunity for metal production but by itself it is not a major reason to be optimistic or pessimistic of SBSP.



15/ In the long-run, I am very optimistic about SBSP and I think it will be crucial to health of our planet. Studies predict that energy use on Earth will continue to increase *despite* calls for sustainability.



16/ The 1-sigma estimate of published studies is that power demand may increase by a factor of 5 by 2100. That means the entire supply chain, making and then using the power, will increase by a factor of 5. Very bad for planet Earth! But we are a short-sighted & divisive species.



17/ (image in prior: education.nationalgeographic.org/resource/pollu…) A practical solution to solving Earth’s climate and environment problems should not expect a magical rewriting or human nature to succeed. We should plan for increased energy use. But make it clean, and move the supply chain off-Earth



18/ To make that approach really sustainable, we will need even more recycling, which requires even more energy! The beauty of SBSP is that, in the long run, about 95% of the energy sector *and the supply chain that supports it* can be moved off planet. And with it…



19/ …most of the computing sector and its supply chain can be moved off-planet. By 2100 that could be ~half of our environmental burden moved off planet. One thing will become inexorably more costly: real estate on Earth. Everything else drops in cost. SBSP becomes viable.



20/ But that is really long-term, decades in the future requiring ongoing progress in robotics and AI for off-Earth industry. I am convinced we will get there in the long term. But what about near term? Should we be convinced of SBSP like Mankins and now apparently Pete Worden?



21/ I think we need continued tech progress to really prove it — that’s the way it always is with technology —, but ESA just commissioned two studies which both came back with positive responses that it is achievable. It may help the climate crisis so it is a tiny cost to try it.



22/ I am convinced it is a no-brainer to place this bet. Even if it takes a bit longer to become economic than what we think, programs like SBSP communicate confidence in the future. This motivates education among young people and a more optimistic world.



23/ And because it is a space project focused on saving Earth instead of a minority of people settling on Mars, it is likely to gain broader political support, which helps space overall (and therefore also helps the economics of settling Mars). End 🧵
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/21/2022 01:51 pm
Lunar ISRU and SBSP go hand in hand they will make each other cheaper but its a chicken and egg thing. If we can start building SBSP without ISRU then market is there to commercially drive ISRU. Launch demand will also go through roof resulting cheaper RLVs.

Low cost ISRU requires access to large quantities of low consumption cost power ie SBSP. Cheaper lunar fuel becomes then cheaper in space transport becomes. Given GW power stations and lasers its possible to move goods around in space without using any fuel, but that is long way off.

Title: Re: Solar Power Satellites
Post by: CameronD on 10/25/2022 04:44 am
Another overview article from Science, focused on recent development: Space-based solar power is getting serious—can it solve Earth’s energy woes? (https://www.science.org/content/article/space-based-solar-power-getting-serious-can-it-solve-earth-s-energy-woes)

Quote
Late last month in Munich, engineers at the European aerospace firm Airbus showed off what might be the future of clean energy. They collected sunlight with solar panels, transformed it into microwaves, and beamed the energy across an aircraft hangar, where it was turned back to electricity that, among other things, lit up a model of a city. The demo delivered just 2 kilowatts over 36 meters, but it raised a serious question: Is it time to resurrect a scheme long derided as science fiction and launch giant satellites to collect solar energy in space? In a high orbit, liberated from clouds and nighttime, they could generate power 24 hours a day and beam it down to Earth.

“It’s not new science, it’s an engineering problem,” says Airbus engineer Jean-Dominique Coste. “But it’s never been done at [large] scale.”

Well.. I've been following along for a while and as impressive as that is, as an engineer, I'm still a skeptic.  Perhaps when someone demonstrates delivering 2kW from GEO down to a rectenna on earth I'll reconsider,  but until then I can think of several problems that aren't predominantly "engineering" at all... they're just basic physics:

1. Our atmosphere contains significant and randomly-varying amounts of water vapour and folks world-wide speak of Global Warming with horror.  What will heating up water vapour in the atmosphere between the ground and the Power Sat (like a giant microwave oven) do exactly?

2. They claim the link could run 24/7, providing base-load power to anywhere you like.  Does this mean the beam is immune from external environmental effects (eg. wide-spectrum electrical storms/lightning)? Have they tested that??

3. What about airline traffic?  Presumably there would need to be a fixed no-fly zone from the ground upwards, because I'd sure not like to be on any plane that happens to fly through the beam.

4. Whilst I'm on the subject of EMI, there are basic IEC (internationally-recognised) regs to stop people doing exactly what the SBSP people propose to do.  Is there a workable way around that that doesn't (quite literally) fry everything nearby??

As if satellite up-links aren't bad enough!...
 
Title: Re: Solar Power Satellites
Post by: Asteroza on 10/25/2022 07:54 am
Another overview article from Science, focused on recent development: Space-based solar power is getting serious—can it solve Earth’s energy woes? (https://www.science.org/content/article/space-based-solar-power-getting-serious-can-it-solve-earth-s-energy-woes)

Quote
Late last month in Munich, engineers at the European aerospace firm Airbus showed off what might be the future of clean energy. They collected sunlight with solar panels, transformed it into microwaves, and beamed the energy across an aircraft hangar, where it was turned back to electricity that, among other things, lit up a model of a city. The demo delivered just 2 kilowatts over 36 meters, but it raised a serious question: Is it time to resurrect a scheme long derided as science fiction and launch giant satellites to collect solar energy in space? In a high orbit, liberated from clouds and nighttime, they could generate power 24 hours a day and beam it down to Earth.

“It’s not new science, it’s an engineering problem,” says Airbus engineer Jean-Dominique Coste. “But it’s never been done at [large] scale.”

Well.. I've been following along for a while and as impressive as that is, as an engineer, I'm still a skeptic.  Perhaps when someone demonstrates delivering 2kW from GEO down to a rectenna on earth I'll reconsider,  but until then I can think of several problems that aren't predominantly "engineering" at all... they're just basic physics:

1. Our atmosphere contains significant and randomly-varying amounts of water vapour and folks world-wide speak of Global Warming with horror.  What will heating up water vapour in the atmosphere between the ground and the Power Sat (like a giant microwave oven) do exactly?

2. They claim the link could run 24/7, providing base-load power to anywhere you like.  Does this mean the beam is immune from external environmental effects (eg. wide-spectrum electrical storms/lightning)? Have they tested that??

3. What about airline traffic?  Presumably there would need to be a fixed no-fly zone from the ground upwards, because I'd sure not like to be on any plane that happens to fly through the beam.

4. Whilst I'm on the subject of EMI, there are basic IEC (internationally-recognised) regs to stop people doing exactly what the SBSP people propose to do.  Is there a workable way around that that doesn't (quite literally) fry everything nearby??

As if satellite up-links aren't bad enough!...

Are you aware that RF power beaming for SPS is generally slated for a power density so low it qualifies as a light sunburn if you stay out all day under it? The whole microwave deathray fear is a significant public relations factor that shaped that part of SPS design (the other being available atmospheric windows and the distances involved for GEO SPS). It's why a sub-MW GEO demo is functionally not possible because of the required transmitter area (because by that point, you may as well build the full 1GW powerstation). Most transmission demos proposed are for LEO sats when passing briefly over a testing receiver ground station.

Laser SPS is always going to have an image problem though, even if you managed to make the light intensity at the receiver something sunburn level. That, and by definition you want to crank a laser setup to heat ray levels, when feeding high concentration PV or some sort of molten salt receiver if delivering thermal power.
Title: Re: Solar Power Satellites
Post by: CameronD on 10/27/2022 02:04 am
Are you aware that RF power beaming for SPS is generally slated for a power density so low it qualifies as a light sunburn if you stay out all day under it? The whole microwave deathray fear is a significant public relations factor that shaped that part of SPS design (the other being available atmospheric windows and the distances involved for GEO SPS). It's why a sub-MW GEO demo is functionally not possible because of the required transmitter area (because by that point, you may as well build the full 1GW powerstation). Most transmission demos proposed are for LEO sats when passing briefly over a testing receiver ground station.

Laser SPS is always going to have an image problem though, even if you managed to make the light intensity at the receiver something sunburn level. That, and by definition you want to crank a laser setup to heat ray levels, when feeding high concentration PV or some sort of molten salt receiver if delivering thermal power.

Yes, that's the issue isn't it?  Due to power density limitation, the only way SPS-to-Earth can practically work is at efficiencies so low that it (almost) becomes pointless to do so in the first place.  To my mind, Microwave Laser SPS from GEO is the only system that really makes engineering sense - but then perhaps augmenting existing solar farms with a visible light laser SPS in LEO, tuned to the PV's optimum frequency, would be a better idea??  Even then EMI would still be somewhat of an issue and it's hard to imagine there'd be much cost benefit over directly using that ultimate spread-spectrum SPS power source, the Sun.

Off-earth SPS for a Moon or Mars base is a different story, but I don't see anyone trying to sell that as and end game in itself - they all seem to want to 'save the world'.. probably because that's where they see an existing market.
 
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/27/2022 04:33 am
Are you aware that RF power beaming for SPS is generally slated for a power density so low it qualifies as a light sunburn if you stay out all day under it? The whole microwave deathray fear is a significant public relations factor that shaped that part of SPS design (the other being available atmospheric windows and the distances involved for GEO SPS). It's why a sub-MW GEO demo is functionally not possible because of the required transmitter area (because by that point, you may as well build the full 1GW powerstation). Most transmission demos proposed are for LEO sats when passing briefly over a testing receiver ground station.

Laser SPS is always going to have an image problem though, even if you managed to make the light intensity at the receiver something sunburn level. That, and by definition you want to crank a laser setup to heat ray levels, when feeding high concentration PV or some sort of molten salt receiver if delivering thermal power.

Yes, that's the issue isn't it?  Due to power density limitation, the only way SPS-to-Earth can practically work is at efficiencies so low that it (almost) becomes pointless to do so in the first place.  To my mind, Microwave Laser SPS from GEO is the only system that really makes engineering sense - but then perhaps augmenting existing solar farms with a visible light laser SPS in LEO, tuned to the PV's optimum frequency, would be a better idea??  Even then EMI would still be somewhat of an issue and it's hard to imagine there'd be much cost benefit over directly using that ultimate spread-spectrum SPS power source, the Sun.

Off-earth SPS for a Moon or Mars base is a different story, but I don't see anyone trying to sell that as and end game in itself - they all seem to want to 'save the world'.. probably because that's where they see an existing market.
 
The beaming efficiencies of 50% is what I've seen. That is why we need pilot 1MW project which would give us real world results. Most important thing with SSP is its 24/7 unlike terrestrial wind and solar.
With current launch costs there is no way SSP is going be economically competitive with other green solutions. Then again terrrestrial solar was very expensive 30 years ago and air travel 70 years ago.
Cost of building SSP will fall dramatically as more are built just need to get ball rolling.
Title: Re: Solar Power Satellites
Post by: Asteroza on 10/27/2022 06:04 am
Are you aware that RF power beaming for SPS is generally slated for a power density so low it qualifies as a light sunburn if you stay out all day under it? The whole microwave deathray fear is a significant public relations factor that shaped that part of SPS design (the other being available atmospheric windows and the distances involved for GEO SPS). It's why a sub-MW GEO demo is functionally not possible because of the required transmitter area (because by that point, you may as well build the full 1GW powerstation). Most transmission demos proposed are for LEO sats when passing briefly over a testing receiver ground station.

Laser SPS is always going to have an image problem though, even if you managed to make the light intensity at the receiver something sunburn level. That, and by definition you want to crank a laser setup to heat ray levels, when feeding high concentration PV or some sort of molten salt receiver if delivering thermal power.

Yes, that's the issue isn't it?  Due to power density limitation, the only way SPS-to-Earth can practically work is at efficiencies so low that it (almost) becomes pointless to do so in the first place.  To my mind, Microwave Laser SPS from GEO is the only system that really makes engineering sense - but then perhaps augmenting existing solar farms with a visible light laser SPS in LEO, tuned to the PV's optimum frequency, would be a better idea??  Even then EMI would still be somewhat of an issue and it's hard to imagine there'd be much cost benefit over directly using that ultimate spread-spectrum SPS power source, the Sun.

Off-earth SPS for a Moon or Mars base is a different story, but I don't see anyone trying to sell that as and end game in itself - they all seem to want to 'save the world'.. probably because that's where they see an existing market.
 

You're conflating some things here. The old SPS studies focused on a specific SPS configuration (GEO, low frequency) so that basically defined the headspace for a long time.

GEO made pointing relatively easy. Early transmitter designs were just huge arrays of parabolic dishes driven by big gyrotrons, not fancy pants ESA's. They also expected to use a giant rotary joint pushing the whole 1GW+ through them though, which is an enormous pain.

Once you have a specific frequency, the physics of the transmission are largely locked in based on transmitter aperture size and distance. Bigger transmitter antenna allows small spot size (thus receiver power density), down to the limits imposed by the chosen frequency itself. The 1km transmitter and 5km receiver designs of the past were reasonable compromises given the frequencies chosen, side lobes, and the desired power density. The efficiency of the rectenna is pretty good, and gyrotron efficiency hasn't really changed over the years (if you go the gyrotron route).

The RF power density limitation isn't necessarily a huge downer either, since it keeps some aspects simpler/cheaper. Getting excessively obsessed with end-to-end efficiency is dumb, when the only valid metric is $/kw delivered all-in (since that is what you will be compared with to terrestrial sources)(compared to terrestrial PV also needs to factor in storage). Yes, efficiency plays into that as poor efficiency increases required mass to orbit, and percent levels of efficiency change can cut whole launches.

There are valid non-GEO arrangements for SPS now (typically MEO or HEEO), along with some higher frequency choices opened up by new electronics and electronically steered phased arrays. There are still atmospheric windows to contend with, but generally nicer in RF than optical. There was that wacky space grid proposal from india, involving MEO orbital microwave reflectors (think solar sails) getting fired on by oddball SPS in SSO along with terrestrial power generators to relay power to markets.

Laser SPS firing on tuned PV is a thing, just as much as a thermal receiver. The ideal starting market being for the island power market where it's almost impossible to setup a large rectenna in a suitable place. For any place that can accomodate a full size rectenna though, running PV under the rectenna seems to be an easy win, especially with the solar cofarming setups to run agriculture underneath a less than 100% coverage solar arrays.


In any event the chinese are serious about a LEO beaming demo in the kilowatt range, so the real results from that will drive any further funding if the Caltech demo doesn't do it first. Or the results will show real world efficiency is much worse, killing off RF SPS research for the foreseeable future (laser is still open to debate, as lasers are still improving at significant rates, unlike RF transmitter technology).
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/27/2022 10:01 am


Or the results will show real world efficiency is much worse, killing off RF SPS research for the foreseeable future (laser is still open to debate, as lasers are still improving at significant rates, unlike RF transmitter technology).
Laser does result in considerably smaller receiver ie solar panel which is big plus for lunar assets that need power during lunar night. To be useful on earth receiver has to have lot of clear skies at night in which its ideal location for terrestrial solar and battery backup.

Title: Re: Solar Power Satellites
Post by: edzieba on 10/27/2022 12:15 pm
Laser also has the nice property that it meshes with any existing investment with groundside solar arrays. Groundside arrays capture solar directly during the day, and are illuminated by laser 24/7 (or dusk-night-dawn if you are somehow hitting panel thermal limits). That way, you can think of SBSS as an alternative to local battery-based (or pumped hydro or similar) power buffers with bonus daytime power generation augmentation, rather than needing to 'compete' with renewables directly (though since most renewables are variable-supply, you'd still need a fully burdened cost for comparison that includes power buffering, rather than just peak daytime return).
Title: Re: Solar Power Satellites
Post by: lamontagne on 10/27/2022 04:14 pm
Laser also has the nice property that it meshes with any existing investment with groundside solar arrays. Groundside arrays capture solar directly during the day, and are illuminated by laser 24/7 (or dusk-night-dawn if you are somehow hitting panel thermal limits). That way, you can think of SBSS as an alternative to local battery-based (or pumped hydro or similar) power buffers with bonus daytime power generation augmentation, rather than needing to 'compete' with renewables directly (though since most renewables are variable-supply, you'd still need a fully burdened cost for comparison that includes power buffering, rather than just peak daytime return).
If there is no storage, then solar power satellites would need to be significantly overbuilt to meet peak load?  You could not sell all your potential production but only a variable portion?
Plus there will eventually be significant battery storage built for transportation, plus some storage for short term peaks and load balancing, already a small existent market?
Title: Re: Solar Power Satellites
Post by: edzieba on 10/27/2022 05:22 pm
Laser also has the nice property that it meshes with any existing investment with groundside solar arrays. Groundside arrays capture solar directly during the day, and are illuminated by laser 24/7 (or dusk-night-dawn if you are somehow hitting panel thermal limits). That way, you can think of SBSS as an alternative to local battery-based (or pumped hydro or similar) power buffers with bonus daytime power generation augmentation, rather than needing to 'compete' with renewables directly (though since most renewables are variable-supply, you'd still need a fully burdened cost for comparison that includes power buffering, rather than just peak daytime return).
If there is no storage, then solar power satellites would need to be significantly overbuilt to meet peak load?  You could not sell all your potential production but only a variable portion?
Plus there will eventually be significant battery storage built for transportation, plus some storage for short term peaks and load balancing, already a small existent market?
You don't need to compete with an extreme "zero storage" setup, but compete with the amount of storage needed (and panel overprovisioning to handle limited capacity factor, too) needed to meet 24/7 baseload demands.
IIRC rough rule of thumb is 12x the average demand over 24h = the required battery storage needed if supply is purely from intermittent solar (e.g. if average demand over a 24h cycle is 2MW, you need 24MWh battery capacity to ensure no dropouts) along with sufficient provisioning of solar panels to charge that battery bank during daylight hours. With SBSP supplying that 2MW during the night hours (in reality a bit lower, due to reduced demand through the night), then your daytime solar farm can be substantially shrunk (no longer needs to charge the batteries) along with eliminating most of the battery storage requirements.
IIRC current grid-scale battery installations are on the order of ~$200/KWh, so SBSP would be roughly competitive somewhere on the order of ~$2400/KW. Possibly higher as you can eliminate some extra costs of grid switching gear (to handle load and unload of the batteries), land area needed for the batteries, and geopolitical costs associated with mass Lithium mining. Batteries will probably continue to drop in price, but mass SBSP installs should also see economics of scale benefits too.
Title: Re: Solar Power Satellites
Post by: CameronD on 10/28/2022 12:00 am
You don't need to compete with an extreme "zero storage" setup, but compete with the amount of storage needed (and panel overprovisioning to handle limited capacity factor, too) needed to meet 24/7 baseload demands.
IIRC rough rule of thumb is 12x the average demand over 24h = the required battery storage needed if supply is purely from intermittent solar (e.g. if average demand over a 24h cycle is 2MW, you need 24MWh battery capacity to ensure no dropouts) along with sufficient provisioning of solar panels to charge that battery bank during daylight hours. With SBSP supplying that 2MW during the night hours (in reality a bit lower, due to reduced demand through the night), then your daytime solar farm can be substantially shrunk (no longer needs to charge the batteries) along with eliminating most of the battery storage requirements.

If you intend to keep the lights on 24/7, then no matter what sized power system you're looking at you need some level of storage - like perpetual motion machines, "zero storage" is a myth.

Traditional power stations provide continuous (both base-load and peak) power by converting the stored energy they have on tap (in the form of coal, fuel, hydro, nuclear, etc) into electricity.  With no stored energy to draw on, solar, wind and wave power cannot provide electricity 100% of the time hence they need some form of power storage to hold up the output voltage/frequency - even if only for a few milliseconds -  or the power system fails.  "Zero storage" proponents typically ignore this fact and rely on "The Grid" (in reality, a nearby power station's complex and expensive control systems) to provide the "storage" for them.

AIUI, all of the SPS proposals discussed thus far cannot provide continuous power by themselves because the link between the satellite and ground station isn't immune to interference, meaning that, just like solar, some amount of instant power retrieval and suitably-sized storage (ie. a lithium or similar battery bank) is required to keep the power system alive.
Title: Re: Solar Power Satellites
Post by: edzieba on 10/28/2022 10:40 am
You don't need to compete with an extreme "zero storage" setup, but compete with the amount of storage needed (and panel overprovisioning to handle limited capacity factor, too) needed to meet 24/7 baseload demands.
IIRC rough rule of thumb is 12x the average demand over 24h = the required battery storage needed if supply is purely from intermittent solar (e.g. if average demand over a 24h cycle is 2MW, you need 24MWh battery capacity to ensure no dropouts) along with sufficient provisioning of solar panels to charge that battery bank during daylight hours. With SBSP supplying that 2MW during the night hours (in reality a bit lower, due to reduced demand through the night), then your daytime solar farm can be substantially shrunk (no longer needs to charge the batteries) along with eliminating most of the battery storage requirements.
If you intend to keep the lights on 24/7, then no matter what sized power system you're looking at you need some level of storage - like perpetual motion machines, "zero storage" is a myth.

Traditional power stations provide continuous (both base-load and peak) power by converting the stored energy they have on tap (in the form of coal, fuel, hydro, nuclear, etc) into electricity.  With no stored energy to draw on, solar, wind and wave power cannot provide electricity 100% of the time hence they need some form of power storage to hold up the output voltage/frequency - even if only for a few milliseconds -  or the power system fails.  "Zero storage" proponents typically ignore this fact and rely on "The Grid" (in reality, a nearby power station's complex and expensive control systems) to provide the "storage" for them.
If you're counting unburnt hydrocarbon fuels as 'stored energy' then we can also point at the Sun's fusion fuel as 'stored energy'. Both rely on your power plant (gas turbine or SPSS) operating at below nominal capacity in order to have some 'reserve' available to be called upon. At least you don't ever need to truck in more Sun!

And since the literal first line of my post was eschewing 'zero storage' setups, no further need to tilt that that particular windmill.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 10/29/2022 04:53 am
Recent webinar on SBSP. Mankins has good point about solar power being critical for accessing lunar resources. Those resources will make construction of SBSP stations cheaper.

https://youtu.be/eixRMWH-c1k
Title: Re: Solar Power Satellites
Post by: su27k on 11/21/2022 02:44 am
DARPA powerbeaming RFI: https://sam.gov/opp/33e1fb52f3a04aeb8f099d71c85aca41/view

Tactical Wireless Power Beaming Technologies for Energy Web Dominance Request for Information

This Request for Information (RFI) from the Defense Advanced Research Projects Agency (DARPA)’s Tactical Technology Office (TTO) seeks technologies and innovative solutions for efficient, kilometer-range radio frequency (RF) kilowatt-class power beaming, distributed apertures for dynamic coherent beamforming, the conversion of RF to electrical energy, and RF energy relays in a lightweight, size-limited payload.

Responses to this RFI will be used to inform and explore future programs within the Tactical Technology Office that advance the ability of multiple ground assets to dynamically move energy across a network of small aircraft equipped with energy receiving and relay technologies. This RF power beaming and relay concept is expected to serve as a component of a more expansive energy web of power generation, transfer relays and receiving solutions, enabling the DoD to dynamically distribute energy resources to more flexibly deliver military effects.

Intellectual or other privileged or proprietary information contained in responses to this RFI will not be distributed outside of the Department of Defense (DoD) or U.S. Government employees from other Government agencies who are working with DARPA on this RFI. In the event that a new DARPA program is developed in response to this RFI and a solicitation is issued, no intellectual or other proprietary information received in response to this RFI will be divulged to  entities outside the U.S. Government.
Title: Re: Solar Power Satellites
Post by: su27k on 11/21/2022 02:51 am
Another overview article from Scientific American: Is Space-Based Solar Power Ready for Its Moment in the Sun? (https://www.scientificamerican.com/article/is-space-based-solar-power-ready-for-its-moment-in-the-sun/)

Quote
When inventor Charles Fritts created the first crude solar photovoltaic cells in the 1880s, one might have thought the achievement would rapidly revolutionize global electricity production. There is, after all, no power source cheaper, cleaner and more ubiquitous than sunlight. Yet despite enormous (and ongoing) technical advances making solar power ever more capable and affordable, some 140 years on it still supplies less than 5 percent of the world’s electricity. For all its benefits, solar power does have drawbacks that can limit its use—chief among them the fact that half the planet’s surface is in darkness at any given time.
Title: Re: Solar Power Satellites
Post by: CameronD on 11/21/2022 03:36 am
DARPA powerbeaming RFI: https://sam.gov/opp/33e1fb52f3a04aeb8f099d71c85aca41/view

Tactical Wireless Power Beaming Technologies for Energy Web Dominance Request for Information

This Request for Information (RFI) from the Defense Advanced Research Projects Agency (DARPA)’s Tactical Technology Office (TTO) seeks technologies and innovative solutions for efficient, kilometer-range radio frequency (RF) kilowatt-class power beaming, distributed apertures for dynamic coherent beamforming, the conversion of RF to electrical energy, and RF energy relays in a lightweight, size-limited payload.

Maybe it's something else, but I read in passing that the recently-returned X-37B had a prototype SPS payload on board:

Quote
For example, we know that OTV-6 tested the U.S. Naval Research Laboratory's Photovoltaic Radio-frequency Antenna Module. This device, about the size of a pizza box, is designed to convert solar energy into microwaves, which can then be beamed down to Earth. Its work could help bring space-based solar power closer to reality, experiment team members have said.

https://www.space.com/space-force-x-37b-space-plane-otv-6-mission-ends
https://www.space.com/x-37b-space-plane-solar-power-beaming
Title: Re: Solar Power Satellites
Post by: Asteroza on 11/21/2022 03:51 am
DARPA powerbeaming RFI: https://sam.gov/opp/33e1fb52f3a04aeb8f099d71c85aca41/view

Tactical Wireless Power Beaming Technologies for Energy Web Dominance Request for Information

This Request for Information (RFI) from the Defense Advanced Research Projects Agency (DARPA)’s Tactical Technology Office (TTO) seeks technologies and innovative solutions for efficient, kilometer-range radio frequency (RF) kilowatt-class power beaming, distributed apertures for dynamic coherent beamforming, the conversion of RF to electrical energy, and RF energy relays in a lightweight, size-limited payload.

Responses to this RFI will be used to inform and explore future programs within the Tactical Technology Office that advance the ability of multiple ground assets to dynamically move energy across a network of small aircraft equipped with energy receiving and relay technologies. This RF power beaming and relay concept is expected to serve as a component of a more expansive energy web of power generation, transfer relays and receiving solutions, enabling the DoD to dynamically distribute energy resources to more flexibly deliver military effects.

Intellectual or other privileged or proprietary information contained in responses to this RFI will not be distributed outside of the Department of Defense (DoD) or U.S. Government employees from other Government agencies who are working with DARPA on this RFI. In the event that a new DARPA program is developed in response to this RFI and a solicitation is issued, no intellectual or other proprietary information received in response to this RFI will be divulged to  entities outside the U.S. Government.

I get the feeling DARPA feels an RF based tactical wireless power beaming solution is preferred, as it allows easier timesharing and split ops, compared to the 1-to-1 relationship of laser systems. Also, in theory it could just be another mode of advanced ESA radars, meaning any airplane with a substantial radar could provide power if it can be programmed for it (from fighters to AWACS), beaming power to small drones (kilowatt class is pretty small all things considered)
Title: Re: Solar Power Satellites
Post by: LMT on 11/21/2022 04:50 am
Still, commercial GEO SSP must be a multi-km structure in a zone that's radar-blind to objects under 30 cm.  Impacts would be frequent and unavoidable.  Impact debris would not deorbit, but would continually intersect GEO, setting up further GEO impacts, most especially with the immense SSP structure itself:  i.e., a Kessler cascade generator. 

Choi and Choi are developing an SSP disposal patent (https://iafastro.directory/iac/paper/id/62932/abstract-pdf/IAC-21,C3,1,9,x62932.brief.pdf) which aims to transfer the retired structure to a distant Sun-Earth L4 / L5 graveyard.

Their patent development is ongoing, so one can only speculate.  Given the structure's great dry mass, a very-high-ISP electric propulsion system might be needed to limit propellant mass.  In that hypothetical case, high ISP corresponds with low thrust per kW, unavoidably (https://forum.nasaspaceflight.com/index.php?topic=51387.msg2278064#msg2278064), so disposal is slow; i.e., a spiraling orbit.  That leaves a risk on the table:  if a significant impact occurred while the structure were still in GEO, a Kessler cascade could kick off long before the structure reached safety.

Quote from: Choi and Choi 2021
...at present, [GEO satellites] are moved to the graveyard orbit by increasing their altitudes by 200-300 km. However, this approach is not applicable for giga watt-class space solar power satellites whose dimensions are several kilometers because it is highly possible for space solar power satellites to collide with other satellites in the graveyard orbit and cause Domino-like collisions (Kessler Syndrome). For this reason, the disposal of space solar power satellites could be the biggest dilemma...

What GEO SSP disposal methods might be both efficient and also robust against Kessler cascade?

Posts:  1 (https://forum.nasaspaceflight.com/index.php?topic=35013.msg2363275#msg2363275) 2 (https://forum.nasaspaceflight.com/index.php?topic=35013.msg2363335#msg2363335) 3 (https://forum.nasaspaceflight.com/index.php?topic=35013.msg2363366#msg2363366)

Video:  ESA:  Space debris 2017 - a journey to Earth (https://dlmultimedia.esa.int/download/public/videos/2017/04/001/1704_001_AR_EN.mp4)
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/21/2022 07:15 am
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Title: Re: Solar Power Satellites
Post by: LMT on 11/21/2022 03:24 pm
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean (https://www.powerengineeringint.com/solar/novel-robotics-for-solar-pv-construction-and-maintenance/), but actually repair?

-

The unaddressed, blocking GEO SSP issue looms large.  Does it emerge from the blind spot, or does the blind spot grow around it?
Title: Re: Solar Power Satellites
Post by: lamontagne on 11/21/2022 05:37 pm
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean (https://www.powerengineeringint.com/solar/novel-robotics-for-solar-pv-construction-and-maintenance/), but actually repair?

-

The unaddressed, blocking GEO SSP issue looms large.  Does it emerge from the blind spot, or does the blind spot grow around it?
On Earth, people are still much cheaper than robots.  So there is no user case.
In space, it should be the other way around, but the space robots don't exist yet.  SO it's all a bit theoretical.
Title: Re: Solar Power Satellites
Post by: LMT on 11/21/2022 08:30 pm
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean (https://www.powerengineeringint.com/solar/novel-robotics-for-solar-pv-construction-and-maintenance/), but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
Title: Re: Solar Power Satellites
Post by: jdon759 on 11/22/2022 01:45 am
To deal with disposal Kessler issues, instead of having in the actual GEO belt,  why not have it a few 10s of km above, between GEO and graveyard? Make use of the impressive SEP array it will need for disposal to keep it orbiting at the right period.  Bonus is that if there is a debris-generating event, the debris will be flung into a higher orbit because it will be unpowered.  Disadvantage is being closer to GEO graveyard.  But if the SEP array was powerful enough, it could be above the graveyard instead.

The station would need to carry a lot more fuel though.  Probably need refuelling fairly regularly, and would be hard to rendezvous with.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 11/22/2022 04:44 am
Yes, space debris (or more accurately MMOD) is the main problem with SBSP, as I outlined here (https://forum.nasaspaceflight.com/index.php?topic=45597.msg2157048#msg2157048):

Not sure if this has been covered, but this thread seems a good place for it:

https://www.fnc.co.uk/discover-frazer-nash/news/frazer-nash-exploring-viability-of-space-based-solar-power-to-help-deliver-net-zero

The UK Government is looking for risky ventures, perhaps to try and compensate for the Brexit damage. They have now commissioned a study into Space Solar Power.

This is relevant to SpaceX because if the cost of launching a solar power station is less than the cost of building the solar arrays, then it might be possible to make a business case for it.

Launch cost = System Weight x Cost per unit mass
Quote
As part of the study, we are looking at the leading three SBSP concepts, from the USA (SPS Alpha), UK (CASSIOPeiA) and China (MR-SPS). SBSP experts John Mankins (USA) and Ian Cash (UK) – the inventors of the first two concepts – are supporting our study.

Problem with using SBSP en-masse is and always has been MMOD.

Micrometeoroid impacts blast away ~100x as much mass as the original impactor, and SBSP offers a huge target (you almost couldn't design something worse for MMOD unless you launch buckets of sand or something). So even if you dodge the big chunks, your solar panels will slowly get "eroded away" by untrackable MMOD. Since each impact multiplies the amount of tiny debris, you don't need too many SBSP installations before you're substantially increasing the MMOD environment in your chosen orbit.

Note that while the Kessler syndrome runaway threshold depends only on the total mass in a certain orbit, a large area satellites will be eroded away into fragments faster than a compact satellite.

One reaction at the time was that radiation pressure would take care of it, but apparently this is not the case (https://conference.sdo.esoc.esa.int/proceedings/sdc5/paper/116/SDC5-paper116.pdf).

Quote from: The Small Size Debris Population in the GEO Belt
The particles with the highest [area-mass ratios] show the largest spread in eccentricity and inclination. Many of the 6 µ objects had even decayed or were ejected from orbit. The debris of 50 μ size and larger, however, formed a fairly stable ring around GEO. The denser parts of that ring extended to about +/- 30° in declination (high ARM particles typically exceeded the maximum increase in inclination of 15°) and spreadover a radial distance of 500-1000 km.



In short, without non-conserved forces (eg drag), the radiation pressure causes the debris objects to "boomerang" back to the original orbit, then oscillate back and forth.
Title: Re: Solar Power Satellites
Post by: LMT on 11/22/2022 02:29 pm
Yes, space debris (or more accurately MMOD) is the main problem with SBSP...

For delicate structures like GEO SSP, artificial debris is already the greater problem.  As the paper stated (https://conference.sdo.esoc.esa.int/proceedings/sdc5/paper/116/SDC5-paper116.pdf),

Quote
...in the sub-mm size range, [artificial] debris fluxes exceed the fluxes of natural meteoroids by at least a factor of 5.

And that debris is slower, at max ~ 800 m/s relative speed; therefore, unlike meteoroids, it can't eject impact debris from GEO-crossing orbits, e.g., to lunar apogee.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 11/22/2022 03:12 pm
Indeed. "MMOD" includes both artificial and natural objects, but my point was more the micro- part (ie specifically referring to debris within that size range).
Title: Re: Solar Power Satellites
Post by: Asteroza on 11/23/2022 06:55 am
Chinese SPS technology maturation marching along...

https://twitter.com/CNSpaceflight/status/1595134353524535296 (https://twitter.com/CNSpaceflight/status/1595134353524535296)
Title: Re: Solar Power Satellites
Post by: lamontagne on 11/23/2022 01:00 pm
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean (https://www.powerengineeringint.com/solar/novel-robotics-for-solar-pv-construction-and-maintenance/), but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
There are window cleaner robots. https://solarcleano.com/en/gallery
There are no repair robots.  Anywhere.  Robots cannot yet repair things autonomously.
Title: Re: Solar Power Satellites
Post by: edzieba on 11/23/2022 01:44 pm
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean (https://www.powerengineeringint.com/solar/novel-robotics-for-solar-pv-construction-and-maintenance/), but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
There are window cleaner robots. https://solarcleano.com/en/gallery
There are no repair robots.  Anywhere.  Robots cannot yet repair things autonomously.
If you accept remote operation is possible, then the existing fleets of underwater ROVs that have replaced humans in many deep-sea installation, maintenance and repair roles are active real-world examples of robotic construction and repair of large structures and complex equipment.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 11/23/2022 02:17 pm
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean (https://www.powerengineeringint.com/solar/novel-robotics-for-solar-pv-construction-and-maintenance/), but actually repair?

-

The unaddressed, blocking GEO SSP issue looms large.  Does it emerge from the blind spot, or does the blind spot grow around it?
On Earth, people are still much cheaper than robots.  So there is no user case.
In space, it should be the other way around, but the space robots don't exist yet.  SO it's all a bit theoretical.
I maintain that with launch cheap enough to make SBSP feasible, humans would be cheaper than robots. And this isn’t bad. We want people to live and work in space, right? Not just take tourist flights?
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 11/23/2022 03:53 pm
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean (https://www.powerengineeringint.com/solar/novel-robotics-for-solar-pv-construction-and-maintenance/), but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
There are window cleaner robots. https://solarcleano.com/en/gallery
There are no repair robots.  Anywhere.  Robots cannot yet repair things autonomously.
If you accept remote operation is possible, then the existing fleets of underwater ROVs that have replaced humans in many deep-sea installation, maintenance and repair roles are active real-world examples of robotic construction and repair of large structures and complex equipment.
Not good example as these ROVs are attached to very expensive manned surface ship. Still lot cheaper than deepsea divers to operate.
Title: Re: Solar Power Satellites
Post by: edzieba on 11/23/2022 04:36 pm
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean (https://www.powerengineeringint.com/solar/novel-robotics-for-solar-pv-construction-and-maintenance/), but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
There are window cleaner robots. https://solarcleano.com/en/gallery
There are no repair robots.  Anywhere.  Robots cannot yet repair things autonomously.
If you accept remote operation is possible, then the existing fleets of underwater ROVs that have replaced humans in many deep-sea installation, maintenance and repair roles are active real-world examples of robotic construction and repair of large structures and complex equipment.
Not good example as these ROVs are attached to very expensive manned surface ship. Still lot cheaper than deepsea divers to operate.
That's a technical limitation due to lack of high-bandwidth wireless communication through several hundred metres of water, rather than a fundamental requirement. Some ROVs now use the tether for comms only, with power being entirely on-board (to allow for a single optical fibre as the link several kilometres long, rather than a bulky copper cable of much more limited length), which is directly analogous to a remotely operated spacecraft with on-board power and a wireless communication link.
Northop Grumman's Mission Extension Vehicles (and later the MRV and MEPs) are also operational remotely operated robotic spacecraft intended purely for servicing satellites.
Title: Re: Solar Power Satellites
Post by: su27k on 11/24/2022 02:43 am
China to use space station to test space-based solar power (https://spacenews.com/china-to-use-space-station-to-test-space-based-solar-power/)

Quote from: SpaceNews
China intends to use its newly-completed Tiangong space station to test key technologies required for space-based polar power, according to a senior space official.

Robotic arms already operating on the outside of Tiangong will be used to test on-orbit assembly of modules for a space-based solar power test system, Yang Hong, chief designer of the Tiangong space station said in a presentation at the ongoing China Space Conference.

The test system will then orbit independently and deploy its solar arrays and other systems. It is likely to test and verify capabilities such as power generation, conversion and transmission.
Title: Re: Solar Power Satellites
Post by: Asteroza on 11/28/2022 10:14 pm
Ian Cash, of CASIOPeiA fame, appears to be putting his money where his mouth is, and starting a company to ride the recent wind of ESA SPS studies.

https://www.spacesolar.co.uk (https://www.spacesolar.co.uk)
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 12/23/2022 05:42 pm
Podcast with founders of Emrod. This is New Zealand startup company (10-20 staff) that specializes in microwave power beaming. Their initial target market is cell towers that need 10kw. NB don't having install products yet, still in development phase and being startup cash poor.
ESA's sudden interest in SBSP had them knocking on Emrod's door as power beaming is most critical technology of SBSP. Looks like they maybe getting some funding from ESA or European aerospace companies. Being Auckland based would be curious to know if they've talked to Rocket Lab.

https://emrod.energy/emrods-vision-for-the-future-on-space-cafe-radio/
Title: Re: Solar Power Satellites
Post by: su27k on 12/24/2022 02:48 am
Northrop Grumman clears key hurdle for space-based solar power (https://spacenews.com/northrop-grumman-tests-space-solar-power/)

Quote from: SpaceNews
Northrop Grumman has completed ground-based tests to demonstrate critical technology required for a 2025 demonstration of space-based solar power.

“As far as the technologies go, we’re very confident in our design and we’ve proven it out,” Tara Theret, Northrop Grumman’s Space Solar Power Incremental Demonstrations and Research (SSPIDR) program director, told SpaceNews. “Now, it’s just building, testing and integrating the rest of the hardware on a challenging timeline.”

Northrop Grumman announced Dec. 15 the successful demonstration of a key element of SSPIDR, the ability to beam radio frequency energy toward various antennas by steering the beam. The testing was conducted in one of Northrop Grumman’s anechoic test chambers in Baltimore.
Title: Re: Solar Power Satellites
Post by: LMT on 12/28/2022 01:44 pm
Scaled solar, from a terrestrial design for comparison (2005).

Refs.

May, N., 2005. Eco-balance of a solar electricity transmission from North Africa to Europe. (https://www.dlr.de/tt/Portaldata/41/Resources/dokumente/institut/system/projects/Ecobalance_of_a_Solar_Electricity_Transmission.pdf) Unpublished Diploma thesis, Technical University of Braunschweig.
 
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 12/28/2022 05:10 pm
Relying on a North Africa country's political stability for your critical energy supplies.
What could possibly go wrong?.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 12/28/2022 05:42 pm
Relying on a North Africa country's political stability for your critical energy supplies.
What could possibly go wrong?.
It’s just an illustration. As mUsk said, Spain would work fine. Also… is Russia better? No.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 12/28/2022 07:33 pm
Relying on a North Africa country's political stability for your critical energy supplies.
What could possibly go wrong?.
It’s just an illustration. As mUsk said, Spain would work fine. Also… is Russia better? No.
What was spainish reaction to have 1000s km2 of their country covered in solar panels.

UK is building large solar farm in Morocco and laying undersea cable. This project will cost $Bs.
Title: Re: Solar Power Satellites
Post by: daedalus1 on 12/28/2022 07:47 pm
Solar power Sat's require large area of land also for the receiver equipment. Not to mention the danger of power transmission microwaves flooding the atmosphere.  The cost of panels on the ground is insignificant compared to the equivalent in GEO.
Title: Re: Solar Power Satellites
Post by: Robotbeat on 12/28/2022 08:31 pm
Relying on a North Africa country's political stability for your critical energy supplies.
What could possibly go wrong?.
It’s just an illustration. As mUsk said, Spain would work fine. Also… is Russia better? No.
What was spainish reaction to have 1000s km2 of their country covered in solar panels.

UK is building large solar farm in Morocco and laying undersea cable. This project will cost $Bs.
The impact of solar panels is less than agriculture; it’s not a big deal. (Not saying that people won’t be dramatic and innumerate about this, though… after all, look at how idiotic people are about nuclear.)
Title: Re: Solar Power Satellites
Post by: TheRadicalModerate on 12/28/2022 08:40 pm
Solar power Sat's require large area of land also for the receiver equipment. Not to mention the danger of power transmission microwaves flooding the atmosphere.  The cost of panels on the ground is insignificant compared to the equivalent in GEO.

What's the state of the art with respect to shorter wavelengths for beaming power?  At optical wavelengths, receivers can be quite small, because diffraction isn't that big a problem from GEO.

Last I heard, there was some discussion about using stratospheric aerostats to collect short-wavelength stuff (because the mid-stratosphere and mesosphere are very dry, and therefore transparent to optical), but it was really hard to do heat rejection with high-power optical lasers in space.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 12/29/2022 09:25 am
Solar power Sat's require large area of land also for the receiver equipment. Not to mention the danger of power transmission microwaves flooding the atmosphere.  The cost of panels on the ground is insignificant compared to the equivalent in GEO.
One study had receiver at 10km2 for 1GW output with average microwave power density of 100Wm2. More like 300Wm2 in center and reduced further from centre. Land under receiver can be used from crop growing. Only danger is to humans and animals that spend a bit of time in middle. Keeping wild life out maybe and issue.
Title: Re: Solar Power Satellites
Post by: daedalus1 on 12/29/2022 10:25 am
Solar power Sat's require large area of land also for the receiver equipment. Not to mention the danger of power transmission microwaves flooding the atmosphere.  The cost of panels on the ground is insignificant compared to the equivalent in GEO.
One study had receiver at 10km2 for 1GW output with average microwave power density of 100Wm2. More like 300Wm2 in center and reduced further from centre. Land under receiver can be used from crop growing. Only danger is to humans and animals that spend a bit of time in middle. Keeping wild life out maybe and issue.


And my other significant points?
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 12/29/2022 04:58 pm
Solar power Sat's require large area of land also for the receiver equipment. Not to mention the danger of power transmission microwaves flooding the atmosphere.  The cost of panels on the ground is insignificant compared to the equivalent in GEO.
One study had receiver at 10km2 for 1GW output with average microwave power density of 100Wm2. More like 300Wm2 in center and reduced further from centre. Land under receiver can be used from crop growing. Only danger is to humans and animals that spend a bit of time in middle. Keeping wild life out maybe and issue.


And my other significant points?
Nobody is denying SSP is more expensive today but should fall dramatically with time as  launch and inspace assembly technology advances.

SSP big advantage is it provides reliable 24/7 power close to where it is needed. Northern european countries can't rely on terrestrial solar due to days to weeks of outages from cloudy weather in winter. Place solar panels in sunny north Africa and they are at mercy of local political situation.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 12/31/2022 01:24 am
The impact of solar panels is less than agriculture

I don't think comparing this to one of the single most impactful human activities is the sales pitch you think it is...



That said, I do agree that SBSP is still worse, if for no other reason than cascading Kessler micro-erosion. Remember that while mass determines whether the debris environment is stable, it's the surface area that determines how fast the chain reaction progresses.  :(

(incidentally, it's amazing how few go back and look at Kessler's original papers...)

Right now there's a lot of mass but little surface area, largely because most stuff hasn't broken up yet. If we add large surface area objects into an orbit, any debris too small to dodge suddenly has its spawn rate "turbo-charged."

Since MMOD impacts kick off hundreds of times the original impactor mass, the exponential multiplier is extreme. Just imagine if splitting one Uranium atom produced 100+ fissile neutrons*!  :o




* most of which can't/don't rapidly escape from the "assembly" because they come around once per orbit

Title: Re: Solar Power Satellites
Post by: TrevorMonty on 12/31/2022 03:32 pm
Large space based lasers would deal with lot of smaller debris. Larger objects will need space tugs.
Title: Re: Solar Power Satellites
Post by: TheRadicalModerate on 01/01/2023 09:34 pm
The impact of solar panels is less than agriculture
That said, I do agree that SBSP is still worse, if for no other reason than cascading Kessler micro-erosion. Remember that while mass determines whether the debris environment is stable, it's the surface area that determines how fast the chain reaction progresses.  :(

Isn't it more volumetric density (objects/km³) that drives stability, rather than mass?  All objects larger than a couple of centimeters have roughly the same effect.

GEO is a much more benign environment than LEO, for several reasons:

1) It's just bigger.  That makes threshold volumetric density harder to achieve.

2) More debris is caused by explosions than collisions.  Exploded debris will have a real RAAN and a non-zero inclination, but you're looking at no more than 100m/s closing velocities.  If you get a secondary collision, that's not going to produce the same number of fragments, and their speeds will be even slower.

3) And last but not least, the fact that all nominal objects have RAAN=N/A and inclination=0º is a big help.  Anything that spalls off will have more complicated orbital parameters, but from an energy standpoint, the environment is a lot more benign.

All that said, increasing surface area by 4-5 orders of magnitude isn't going to help matters.  But maybe that's a design issue for your SBSP birds:  If you have thin-film mirrors concentrating light on relatively small photovoltaic arrays, you take some debris damage to the mirrors, but it doesn't really generate any appreciable secondary debris.
Title: Re: Solar Power Satellites
Post by: LMT on 01/01/2023 09:59 pm
[In GEO] you're looking at no more than 100m/s closing velocities...

No, as noted (https://forum.nasaspaceflight.com/index.php?topic=35013.msg2433348#msg2433348), GEO debris hits at up to 800 m/s (https://conference.sdo.esoc.esa.int/proceedings/sdc5/paper/116/SDC5-paper116.pdf), before explosion delta-v factors in.

VLEO is the only low-debris-risk orbit (https://forum.nasaspaceflight.com/index.php?topic=34036.msg1835562#msg1835562) for commercial SSP.  That by itself is reason to focus on VLEO SSP methods.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 01/01/2023 10:51 pm
Large space based lasers would deal with lot of smaller debris.

Geopolitically and astronomically infeasible.

The cheapest way to deal with small debris is to remove big debris.

Larger objects will need space tugs.

Sounds great, but the problem has always been funding.

This, too, has geopolitical problems. 19 of the top 20 high-risk debris objects are Russian upper stages.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 01/01/2023 10:56 pm
The impact of solar panels is less than agriculture
That said, I do agree that SBSP is still worse, if for no other reason than cascading Kessler micro-erosion. Remember that while mass determines whether the debris environment is stable, it's the surface area that determines how fast the chain reaction progresses.  :(

Isn't it more volumetric density (objects/km³) that drives stability, rather than mass?

Massive objects are proportionally harder for aerodynamic drag / radiation pressure to "sweep out." That's why stability is determined by mass.

Aggregate surface area does determine the collision rate. to clarify, aggregate area determines how fast the system "tips over," but aggregate mass determines whether it tips over.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 01/01/2023 11:14 pm
All objects larger than a couple of centimeters have roughly the same effect.

Even the smaller (and far more numerous) objects are problematic.

They still blast off 100s of times their mass in new debris, and they still pose risks and degrade operations. Whipple shields help but they're not 100%. And since there are already vastly more objects in the existing population, the exponential chain reaction moves that much faster.

Don't picture the movie Gravity. Picture a slow-motion "sandblasting" that goes on ceaselessly for the entire 20+ year spacecraft lifespan, and gets worse and worse with each passing decade.


GEO is a much more benign environment than LEO, for several reasons:

1) It's just bigger.  That makes threshold volumetric density harder to achieve.

...

3) And last but not least, the fact that all nominal objects have RAAN=N/A and inclination=0º is a big help.

Point #3 largely counteracts Point #1. LEO is a sphere, but GEO is a ring. That has important (and unaccounted for) implications for density.

Collision rate scales with density squared, so it makes a huge difference.


2) More debris is caused by explosions than collisions.

Partly that's selection bias, because we have inferior radar surveillance in GEO. A debris strike from an untracked object and a mysterious explosion look largely identical.

Exploded debris will have a real RAAN and a non-zero inclination, but you're looking at no more than 100m/s closing velocities.  If you get a secondary collision, that's not going to produce the same number of fragments, and their speeds will be even slower.

...

  Anything that spalls off will have more complicated orbital parameters, but from an energy standpoint, the environment is a lot more benign.

The Moon's orbit is tilted ~5.15°, so debris is perturbed into an inclination up to 10.3°. That means debris strikes at up to ~550 m/s, or ~1.6 Mach at sea level. Not hypersonic, but still "fast as a speeding bullet."  :-\

There are also populations of objects in GEO-crossing orbits (eg GTO) that can collide at up to 4 km/s. See the link below.


You also forgot

4) GEO has much less drag then LEO, so there's less free cleanup of small debris.

5) GEO is much farther away, so radar and optical surveys of debris objects are much less sensitive (by 1/r4 and 1/r2, respectively).


https://physicsworld.com/a/space-debris-threat-to-geosynchronous-satellites-has-been-drastically-underestimated/


In general I concur with your mitigations. Low mass thin film reflectors (and PV itself) is a must! Probably that would remain true if only for economic reasons.
Title: Re: Solar Power Satellites
Post by: LMT on 01/02/2023 12:21 am
The Moon's orbit is tilted ~5.15°, so debris is perturbed into an inclination up to 10.3°. That means debris strikes at up to ~550 m/s...

Or notice the posted (https://forum.nasaspaceflight.com/index.php?topic=35013.msg2445543#msg2445543) study:  max inclinations and impact speeds are actually higher.  For the highest area-to-mass debris, inclination increase can pass 15° -- the actual case for "thin film" SSP Kessler cascades.

There's no real debris solution for commercial GEO SSP.  At present, it's VLEO or nothing.
Title: Re: Solar Power Satellites
Post by: LMT on 01/05/2023 09:42 pm
Launch of Caltech's Space Solar Power Demonstrator (https://www.popsci.com/technology/caltech-solar-energy-power-satellite-prototype-launch/)

Note the camera boom deployment.  In a commercial SSP design, the boom can be enlarged, and the boom tip can be fitted with a field emitter array (FEA) to close the electrical circuit in the space environment.  This would enable electrodynamic drag cancellation (https://forum.nasaspaceflight.com/index.php?topic=45674) without propellant, even in VLEO.  A commercial SSP structure in VLEO sidesteps the crippling debris risk present in other orbits.


https://www.youtube.com/watch?v=c2mgpMy-_mU

https://www.youtube.com/watch?v=jhA39mqS9D8
Title: Re: Solar Power Satellites
Post by: su27k on 01/28/2023 02:29 am
US can’t afford to dawdle on investing in space-based solar power (https://thehill.com/opinion/technology/3831460-us-cant-afford-to-dawdle-on-investing-in-space-based-solar-power/)

Quote from: thehill.com
Is a limitless source of green energy within reach? With unrelenting global reliance on fossil fuels, a worsening climate, and growing dependency on (often-unreliable) renewables, the world desperately needs a solution.

Scientists in the U.S. appeared to come close to one with a recent breakthrough in fusion technology. Unfortunately, while a positive technological advancement, several decades of development are still necessary before fusion becomes a commercially viable energy alternative. Yet there may be another way to alleviate our energy dilemma — and soon. The answer lies in space-based solar power (SSP).
Title: Re: Solar Power Satellites
Post by: InterestedEngineer on 01/31/2023 12:30 am
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Title: Re: Solar Power Satellites
Post by: Twark_Main on 01/31/2023 12:41 am
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?

What math would that be?

An effective counter-argument would have to show that the economic assumptions Elon Musk was making are wrong, and persuasively demonstrating that some other set of cost assumptions should hold.
Title: Re: Solar Power Satellites
Post by: InterestedEngineer on 01/31/2023 01:14 am
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
What math would that be?

The math that compares to ground-based solar.

The math that says the electricity would be competitive in price.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 01/31/2023 01:57 am
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
What math would that be?

The math that compares to ground-based solar.

The math that says the electricity would be competitive in price.
Ground based solar is cheaper per unit but it can't be relied on for baseload even with battery banks.

Title: Re: Solar Power Satellites
Post by: edzieba on 01/31/2023 10:39 am
Ground-based will be cheaper by unit installed capacity (I can't think of any way it couldn't be, apart from land prices spiralling by several hundred thousand times, or some new solar cell technology that only works in vacuum and microgravity).
Ground based is probably cheaper by unit energy actually delivered to the grid (this may trade back and forth depending on location, inclination, local cloud cover, panel install angle, install scale, etc).
Space-based may be cheaper per average unit energy actually available for grid end use when variability is taken into account and compensated for (e.g. with grid-scale battery storage, or adding the fully burdened cost of fossil-fuel-based backup generation capacity). 'Just' massively overprovisioning ground based solar capacity (e.g. spending the SBSP launch costs on more ground panels) is not sufficient itself to guarantee stable generation, as even multinational power grid interconnects cannot help if everyone's panels are obstructed - as happened late last year in Europe, and then later the US. Cessation of subsidisation of fossil fuel generation and incorporation of externality costs of fossil fuel generation into pricing would push the needle further towards SBSP (along with nice side-benefits like energy independence and improved air quality).
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 01/31/2023 03:58 pm
Ground-based will be cheaper by unit installed capacity (I can't think of any way it couldn't be, apart from land prices spiralling by several hundred thousand times, or some new solar cell technology that only works in vacuum and microgravity).
Ground based is probably cheaper by unit energy actually delivered to the grid (this may trade back and forth depending on location, inclination, local cloud cover, panel install angle, install scale, etc).
Space-based may be cheaper per average unit energy actually available for grid end use when variability is taken into account and compensated for (e.g. with grid-scale battery storage, or adding the fully burdened cost of fossil-fuel-based backup generation capacity). 'Just' massively overprovisioning ground based solar capacity (e.g. spending the SBSP launch costs on more ground panels) is not sufficient itself to guarantee stable generation, as even multinational power grid interconnects cannot help if everyone's panels are obstructed - as happened late last year in Europe, and then later the US. Cessation of subsidisation of fossil fuel generation and incorporation of externality costs of fossil fuel generation into pricing would push the needle further towards SBSP (along with nice side-benefits like energy independence and improved air quality).
For Northern countries no avoiding need for  alternative power generation for those cloudy periods. These will typically be fossil fuel powered. Some lucky countries can use hydro which would already exist.
Title: Re: Solar Power Satellites
Post by: LMT on 01/31/2023 05:33 pm
A terrestrial project for baseline comparison:  Xlinks FAQ (https://xlinks.co/faq/)
 
Title: Re: Solar Power Satellites
Post by: LMT on 01/31/2023 07:53 pm
In the same vein as Xlinks:

https://twitter.com/elonmusk/status/1620516627254231040

https://twitter.com/alex_avoigt/status/1620421663333695490
 
Title: Re: Solar Power Satellites
Post by: Asteroza on 02/01/2023 01:38 am
A terrestrial project for baseline comparison:  Xlinks FAQ (https://xlinks.co/faq/)

Xlinks, where Brexit met DESERTEC...
Title: Re: Solar Power Satellites
Post by: su27k on 02/04/2023 04:06 am
Could solar panels in space supply Earth with clean energy? (https://www.nature.com/articles/d41586-023-00279-8)

Quote from: nature.com
Nature looks at five big questions that researchers must answer to make space-based solar power a reality.

1. How can a solar farm be built in space?

2. What kind of solar cells would be used?

3. How will the solar power reach Earth?

4. Will it all be worth the effort?

5. Will it be safe?
Title: Re: Solar Power Satellites
Post by: Twark_Main on 02/04/2023 04:22 am
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
What math would that be?

An effective counter-argument would have to show that the economic assumptions Elon Musk was making are wrong, and persuasively demonstrating that some other set of cost assumptions should hold.

The math that compares to ground-based solar.

The math that says the electricity would be competitive in price.

Yes, the primary "economic assumption" Musk is making is that the electricity would be sold at grid prices. I restored the part of my quote you cut off so you can read it again.  ;)

The obvious way to get around that is to market toward applications where electricity is substantially more expensive than grid electricity. This is why most proposals I've seen are targeting island nations, forward military bases, or times of peak demand when electricity prices spike.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 02/04/2023 04:47 am
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.
Title: Re: Solar Power Satellites
Post by: su27k on 02/04/2023 04:50 am
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.

While I agree that Elon needs to show his work, technically electricity from SBSP is not generated in the country either. If the country is dependent on energy from SBSP, then SBSP too needs to be defended.
Title: Re: Solar Power Satellites
Post by: lamontagne on 02/04/2023 02:14 pm
Ground-based will be cheaper by unit installed capacity (I can't think of any way it couldn't be, apart from land prices spiralling by several hundred thousand times, or some new solar cell technology that only works in vacuum and microgravity).
Ground based is probably cheaper by unit energy actually delivered to the grid (this may trade back and forth depending on location, inclination, local cloud cover, panel install angle, install scale, etc).
Space-based may be cheaper per average unit energy actually available for grid end use when variability is taken into account and compensated for (e.g. with grid-scale battery storage, or adding the fully burdened cost of fossil-fuel-based backup generation capacity). 'Just' massively overprovisioning ground based solar capacity (e.g. spending the SBSP launch costs on more ground panels) is not sufficient itself to guarantee stable generation, as even multinational power grid interconnects cannot help if everyone's panels are obstructed - as happened late last year in Europe, and then later the US. Cessation of subsidisation of fossil fuel generation and incorporation of externality costs of fossil fuel generation into pricing would push the needle further towards SBSP (along with nice side-benefits like energy independence and improved air quality).
For Northern countries no avoiding need for  alternative power generation for those cloudy periods. These will typically be fossil fuel powered. Some lucky countries can use hydro which would already exist.
They can use combustion but it doesn't have to be fossil fuels.  You could use methane or hydrogen generated in off peak periods and that would be CO2 neutral.  The natural gas grid in most countries already stores enough energy for a number of days of operation.  There already are significant storage installations for natural gas that could be used for methane storage. 
Title: Re: Solar Power Satellites
Post by: lamontagne on 02/04/2023 02:19 pm
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.
-I expect Elon is more concerned with the US, that already has the required deserts and lithium resources. 
-Northern Europe needs to make peace with North Africa, problem solved ;-) 
-But also Northern Europe has access to a lot of wind, that can be used in conjugation with batteries (daily storage) and methane, (monthly load spreading using storage).
Title: Re: Solar Power Satellites
Post by: DanClemmensen on 02/04/2023 02:40 pm
Ground-based will be cheaper by unit installed capacity (I can't think of any way it couldn't be, apart from land prices spiralling by several hundred thousand times, or some new solar cell technology that only works in vacuum and microgravity).
Ground based is probably cheaper by unit energy actually delivered to the grid (this may trade back and forth depending on location, inclination, local cloud cover, panel install angle, install scale, etc).
Space-based may be cheaper per average unit energy actually available for grid end use when variability is taken into account and compensated for (e.g. with grid-scale battery storage, or adding the fully burdened cost of fossil-fuel-based backup generation capacity). 'Just' massively overprovisioning ground based solar capacity (e.g. spending the SBSP launch costs on more ground panels) is not sufficient itself to guarantee stable generation, as even multinational power grid interconnects cannot help if everyone's panels are obstructed - as happened late last year in Europe, and then later the US. Cessation of subsidisation of fossil fuel generation and incorporation of externality costs of fossil fuel generation into pricing would push the needle further towards SBSP (along with nice side-benefits like energy independence and improved air quality).
For Northern countries no avoiding need for  alternative power generation for those cloudy periods. These will typically be fossil fuel powered. Some lucky countries can use hydro which would already exist.
They can use combustion but it doesn't have to be fossil fuels.  You could use methane or hydrogen generated in off peak periods and that would be CO2 neutral.  The natural gas grid in most countries already stores enough energy for a number of days of operation.  There already are significant storage installations for natural gas that could be used for methane storage.
Europe has NG storage for more than 60 days usage, mostly in underground depleted NG fields. The problem with methane is that the NG system as a whole is not perfect, so some of it leaks, and it is a powerful greenhouse gas. This would be true even for "green" methane unless the infrastructure was rebuilt. The problem with hydrogen is that the existing NG system cannot accommodate more than about 10% hydrogen, so an entirely new system would need to be put in place before NG could be retired.  Pumped Hydro is really boring, but is probably the best technology for long-term energy storage.  Most stored energy will use short-term (battery) storage, so only "excess" energy goes to long-term storage. This means that the round-trip efficiency is relatively unimportant.

This all relates to "energy independence", which feeds into the SBSP equation. "independence" in a connected world is a slippery concept. In a rational world, we would expect economics to drive the decisions, but in this world, formerly rational partners can do stupid stuff. We used to believe that Russia, the UK, and the USA would remain reliable, rational economic partners. Except for countries like Denmark and the Netherlands that are relatively flat, there is usually a place for pumped hydro.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 02/04/2023 04:12 pm
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.
-I expect Elon is more concerned with the US, that already has the required deserts and lithium resources. 
-Northern Europe needs to make peace with North Africa, problem solved ;-) 
-But also Northern Europe has access to a lot of wind, that can be used in conjugation with batteries (daily storage) and methane, (monthly load spreading using storage).

Terrestrial Solar ONLY. No alternative backup generators using different fuel source. Batteries and pumped Hydro are OK as still powered by solar.
Title: Re: Solar Power Satellites
Post by: DanClemmensen on 02/04/2023 04:25 pm
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.
-I expect Elon is more concerned with the US, that already has the required deserts and lithium resources. 
-Northern Europe needs to make peace with North Africa, problem solved ;-) 
-But also Northern Europe has access to a lot of wind, that can be used in conjugation with batteries (daily storage) and methane, (monthly load spreading using storage).

Terrestrial Solar ONLY. No alternative backup generators using different fuel source. Batteries and pumped Hydro are OK as still powered by solar.
Stored "green" hydrogen is carbon neutral and can be used in "alternative backup generators". Stored "green" methane is carbon neutral, but IMO in practice methane leaks disqualify it.
Title: Re: Solar Power Satellites
Post by: lamontagne on 02/04/2023 04:36 pm
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.
-I expect Elon is more concerned with the US, that already has the required deserts and lithium resources. 
-Northern Europe needs to make peace with North Africa, problem solved ;-) 
-But also Northern Europe has access to a lot of wind, that can be used in conjugation with batteries (daily storage) and methane, (monthly load spreading using storage).

Terrestrial Solar ONLY. No alternative backup generators using different fuel source. Batteries and pumped Hydro are OK as still powered by solar.
Why the limitation?  Are there contest rules somewhere?  Solar produced methane is powered by solar. And displaces fossil fuel methane.
Using methane do go through a dip will use a tiny fraction of the actual energy usage, even if the instant power needs to be high.  And let's not forget that if we do have a solar/wind power base we do away with more than half the world energy use that is lost in combustion in vehicles and power stations.
Title: Re: Solar Power Satellites
Post by: mandrewa on 02/04/2023 04:46 pm
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.
-I expect Elon is more concerned with the US, that already has the required deserts and lithium resources. 
-Northern Europe needs to make peace with North Africa, problem solved ;-) 
-But also Northern Europe has access to a lot of wind, that can be used in conjugation with batteries (daily storage) and methane, (monthly load spreading using storage).

Terrestrial Solar ONLY. No alternative backup generators using different fuel source. Batteries and pumped Hydro are OK as still powered by solar.
Stored "green" hydrogen is carbon neutral and can be used in "alternative backup generators". Stored "green" methane is carbon neutral, but IMO in practice methane leaks disqualify it.

"How green is blue hydrogen?" Robert Howarth, Mark Jacobson
Energy Sci. Eng. 2021

Greatly simplified:

Greenhouse gas footprint per unit of heat energy
(grams CO2 equivalents per MJ)
------------------------------------------------
160 gray hydrogen
150 blue hydrogen
130 natural gas
130 coal
100 diesel oil

"Life-cycle greenhouse gas emissions and net energy assessment of large-scale
hydrogen production via electrolysis and solar PV", Palmer et al

Greatly simplified:

Under realistic, current conditions greenhouse gas emissions from making green hydrogen
with solar cells are roughly the same as making hydrogen from natural gas or coal.

So putting these two papers together, we have:

Greenhouse gas footprint per unit of heat energy
(grams CO2 equivalents per MJ)
------------------------------------------------
160 gray hydrogen
150 blue hydrogen
130 natural gas
130 coal
130 green hydrogen (current practice. This could be greatly improved.)
110 gasoline (estimate from an anonymous source)
100 diesel oil

Note the only thing being compared here is greenhouse gas emissions.  Cost doesn't figure into it. 

I don't know what the greenhouse gas footprint of solar-power satellites would be.  But I'm pretty sure it's not zero.  (Now it might be zero if we mined the resources from the Moon, but that's a distant scenario.)  But I would guess that the greenhouse gas emissions per MJ of electricity generated by solar power satellite and received on the Earth would be considerably less than these other options.
Title: Re: Solar Power Satellites
Post by: lamontagne on 02/04/2023 04:48 pm
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.
-I expect Elon is more concerned with the US, that already has the required deserts and lithium resources. 
-Northern Europe needs to make peace with North Africa, problem solved ;-) 
-But also Northern Europe has access to a lot of wind, that can be used in conjugation with batteries (daily storage) and methane, (monthly load spreading using storage).

Terrestrial Solar ONLY. No alternative backup generators using different fuel source. Batteries and pumped Hydro are OK as still powered by solar.
Stored "green" hydrogen is carbon neutral and can be used in "alternative backup generators". Stored "green" methane is carbon neutral, but IMO in practice methane leaks disqualify it.
Interesting point.  I am curious as to what the leaks would become if we just used the methane for backup power stations and did away with most of the distribution network.  No more gas heating, cooking or base load power generation.  It's really a question of how much energy you can get into a leak proof tank, isn't it?
Because solar is naturally distributed, the methane generation systems would need to be distributed as well, and probably be a mostly new infrastructure?
I guess another alternative is to overbuild solar to such an extent that the backup required becomes quite small, and limited to large installations such as city centers and power hungry industries?
Title: Re: Solar Power Satellites
Post by: lamontagne on 02/04/2023 04:53 pm
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.
-I expect Elon is more concerned with the US, that already has the required deserts and lithium resources. 
-Northern Europe needs to make peace with North Africa, problem solved ;-) 
-But also Northern Europe has access to a lot of wind, that can be used in conjugation with batteries (daily storage) and methane, (monthly load spreading using storage).

Terrestrial Solar ONLY. No alternative backup generators using different fuel source. Batteries and pumped Hydro are OK as still powered by solar.
Stored "green" hydrogen is carbon neutral and can be used in "alternative backup generators". Stored "green" methane is carbon neutral, but IMO in practice methane leaks disqualify it.

"How green is blue hydrogen?" Robert Howarth, Mark Jacobson
Energy Sci. Eng. 2021

Greatly simplified:

Greenhouse gas footprint per unit of heat energy
(grams CO2 equivalents per MJ)
------------------------------------------------
160 gray hydrogen
150 blue hydrogen
130 natural gas
130 coal
100 diesel oil

"Life-cycle greenhouse gas emissions and net energy assessment of large-scale
hydrogen production via electrolysis and solar PV", Palmer et al

Greatly simplified:

Under realistic, current conditions greenhouse gas emissions from making green hydrogen
with solar cells are roughly the same as making hydrogen from natural gas or coal.

So putting these two papers together, we have:

Greenhouse gas footprint per unit of heat energy
(grams CO2 equivalents per MJ)
------------------------------------------------
160 gray hydrogen
150 blue hydrogen
130 natural gas
130 coal
130 green hydrogen (current practice. This could be greatly improved.)
110 gasoline (estimate from an anonymous source)
100 diesel oil

Note the only thing being compared here is greenhouse gas emissions.  Cost doesn't figure into it. 

I don't know what the greenhouse gas footprint of solar-power satellites would be.  But I'm pretty sure it's not zero.  (Now it might be zero if we mined the resources from the Moon, but that's a distant scenario.)  But I would guess that the greenhouse gas emissions per MJ of electricity generated by solar power satellite and received on the Earth would be considerably less than these other options.
Yes but isn't the basic assumption flawed?  We will not be producing hydrogen using fossil fuels once we produce hydrogen using exclusively solar and wind.  Right now blue hydrogen isn't blue, as the solar cells/metals for turbines, etc aren't produced using clean energy.  But eventually they will be.
In Quebec, the blue hydrogen is produced using hydraulic electricity. for example.  Although hydro has a large sunk environmental cost at construction time, for Quebec it has been absorbed for some time now.
Title: Re: Solar Power Satellites
Post by: lamontagne on 02/04/2023 05:10 pm
The two most logical uses for solar hydrogen would be steel production and ammonia production, rather than storage.  This would replace methane as a feedstock for the Haber Bosh process and coal for the steel production process.  There already is an aluminum production process that does away with carbon anodes and produces oxygen rather than CO2.
Thise two application reduce demand significantly, makinf th case for solar more interesting.
Title: Re: Solar Power Satellites
Post by: mandrewa on 02/04/2023 05:13 pm

"How green is blue hydrogen?" Robert Howarth, Mark Jacobson
Energy Sci. Eng. 2021

Greatly simplified:

Greenhouse gas footprint per unit of heat energy
(grams CO2 equivalents per MJ)
------------------------------------------------
160 gray hydrogen
150 blue hydrogen
130 natural gas
130 coal
100 diesel oil

"Life-cycle greenhouse gas emissions and net energy assessment of large-scale
hydrogen production via electrolysis and solar PV", Palmer et al

Greatly simplified:

Under realistic, current conditions greenhouse gas emissions from making green hydrogen
with solar cells are roughly the same as making hydrogen from natural gas or coal.

So putting these two papers together, we have:

Greenhouse gas footprint per unit of heat energy
(grams CO2 equivalents per MJ)
------------------------------------------------
160 gray hydrogen
150 blue hydrogen
130 natural gas
130 coal
130 green hydrogen (current practice. This could be greatly improved.)
110 gasoline (estimate from an anonymous source)
100 diesel oil

Note the only thing being compared here is greenhouse gas emissions.  Cost doesn't figure into it. 

I don't know what the greenhouse gas footprint of solar-power satellites would be.  But I'm pretty sure it's not zero.  (Now it might be zero if we mined the resources from the Moon, but that's a distant scenario.)  But I would guess that the greenhouse gas emissions per MJ of electricity generated by solar power satellite and received on the Earth would be considerably less than these other options.
Yes but isn't the basic assumption flawed?  We will not be producing hydrogen using fossil fuels once we produce hydrogen using exclusively solar and wind.  Right now blue hydrogen isn't blue, as the solar cells/metals for turbines, etc aren't produced using clean energy.  But eventually they will be.
In Quebec, the blue hydrogen is produced using hydraulic electricity. for example.  Although hydro has a large sunk environmental cost at construction time, for Quebec it has been absorbed for some time now.

I've thought along the same lines.  But that raises an interesting question.  Over 80% of the world's solar cells are being made in China.  Part of the reason that the current greenhouse emissions from solar cells are so high is because China burns a lot of coal in the process of making those solar cells.

So why don't the Chinese use their solar cells to make the energy to make solar cells?

The answer must be that it is a question of cost.  Getting energy from coal is cheaper than getting it from solar cells.  And cost is the main thing they care about in China.

And that's the problem in a nutshell, and the reason that global greenhouse gas emissions are steadily increasing.  It's not just China but it's most of the world for which cost is what decides what will be built.

To really make a difference we have to have energy technologies that are cheaper than coal.  It's obvious that solar power satellites are going to start off being more expensive.  But it's a baby-in-the-bathwater situation.

Meanwhile we do know that coal is cheaper than solar cells or windmills because China dominates the production of both of these things, and if either was cheaper than coal that would be what they were using.
Title: Re: Solar Power Satellites
Post by: DanClemmensen on 02/04/2023 05:35 pm
I'm curious, did anyone do the math to couner Elon's claim that power conversion and transmission inefficiencies would economically kill the idea of solar power satellites?
Elon needs to show how he can deliver power 24/7 365 days a year reliably and economicially to North Europe country using terrestrial solar power only that is generated in the country.
That is what SSP should be capable of.
-I expect Elon is more concerned with the US, that already has the required deserts and lithium resources. 
-Northern Europe needs to make peace with North Africa, problem solved ;-) 
-But also Northern Europe has access to a lot of wind, that can be used in conjugation with batteries (daily storage) and methane, (monthly load spreading using storage).

Terrestrial Solar ONLY. No alternative backup generators using different fuel source. Batteries and pumped Hydro are OK as still powered by solar.
Stored "green" hydrogen is carbon neutral and can be used in "alternative backup generators". Stored "green" methane is carbon neutral, but IMO in practice methane leaks disqualify it.
Interesting point.  I am curious as to what the leaks would become if we just used the methane for backup power stations and did away with most of the distribution network.  No more gas heating, cooking or base load power generation.  It's really a question of how much energy you can get into a leak proof tank, isn't it?
Because solar is naturally distributed, the methane generation systems would need to be distributed as well, and probably be a mostly new infrastructure?
I guess another alternative is to overbuild solar to such an extent that the backup required becomes quite small, and limited to large installations such as city centers and power hungry industries?
Europe's 60-day supply of NG is stored primarily underground in depleted oil and NG fields. I have no insight into leaks there. Here in California, we had a huge leak from such a field
    https://en.wikipedia.org/wiki/Aliso_Canyon_gas_leak
and by "huge", I mean an appreciable percentage of California's annual methane leakage.  I have no confidence in distributed storage of methane, but that's a personal opinion.

Closing the loop, again: SBSP will not compete economically it we have viable long-term "green" energy storage.
If you can overbuild your Solar power systems enough to reduce the long-term storage requirement, maybe go ahead and store a heavier hydrocarbon like ethanol or kerosene that is less leak-prone. Kerosene is a good choice because it is "green" jet fuel. IMO it will be quite a while before we have a viable alternative to jet turbines, and even longer before we can retire the jet fleet. Given the infrastructure to produce "green" jet fuel, using it with distributed kerosene-fueled turbo generators is viable. Again, here in California (in Oakland) one of our power plants uses these, albeit with fossil kerosene. They are basically slightly-modified jet engines.

Title: Re: Solar Power Satellites
Post by: lamontagne on 02/04/2023 05:58 pm

I've thought along the same lines.  But that raises an interesting question.  Over 80% of the world's solar cells are being made in China.  Part of the reason that the current greenhouse emissions from solar cells are so high is because China burns a lot of coal in the process of making those solar cells.

So why don't the Chinese use their solar cells to make the energy to make solar cells?

The answer must be that it is a question of cost.  Getting energy from coal is cheaper than getting it from solar cells.  And cost is the main thing they care about in China.

And that's the problem in a nutshell, and the reason that global greenhouse gas emissions are steadily increasing.  It's not just China but it's most of the world for which cost is what decides what will be built.

To really make a difference we have to have energy technologies that are cheaper than coal.  It's obvious that solar power satellites are going to start off being more expensive.  But it's a baby-in-the-bathwater situation.

Meanwhile we do know that coal is cheaper than solar cells or windmills because China dominates the production of both of these things, and if either was cheaper than coal that would be what they were using.
Because they are not there yet.
China has 3000 GW of installed power, but only 300 GW of solar power.  So they use coal, and studies attribute that coal to the solar panel production.
There is no large scale carbon free steel production for the moment in China, or anywhere in the world for that matter.

As the environmental damage of coal is not counted in cost, coal usually wins on cost.  However, solar has started being better than coal even on base cost levels.  So it's really a matter of time until the Chinese build up enough solar and wind to displace the coal.  The more they build, the better the numbers get.  So the answer is that they haven't had the time yet.

Most gains for solar power satellites can be applied to Earth.  The fundamental problems with space solar are:
-Much of it is lost in transmission, negating the availability advantage.
-The infrastructure required is large and hard to scale up to.  In particular, ground level antennas are huge, since power density of the beam is limited to avoid cooking birds and stray people.
-There are a number of unknown costs from maintenance that might sink the concept.
-Launching all that materials from Earth will eventually damage the atmosphere somewhat.
-It's an infrastructure heavy system, that requires central 'plants', the rectenna arrays, and a large distribution system.  Home produced solar power destroys this centralized model by providing absurdly cheap electricity for much of the day.  So the infrastructure costs become too high to maintain, destroying the economical model.  This is not a solved problem for most utilities and will only get worse.



Title: Re: Solar Power Satellites
Post by: lamontagne on 02/04/2023 06:15 pm

Europe's 60-day supply of NG is stored primarily underground in depleted oil and NG fields. I have no insight into leaks there. Here in California, we had a huge leak from such a field
    https://en.wikipedia.org/wiki/Aliso_Canyon_gas_leak
and by "huge", I mean an appreciable percentage of California's annual methane leakage.  I have no confidence in distributed storage of methane, but that's a personal opinion.

Closing the loop, again: SBSP will not compete economically it we have viable long-term "green" energy storage.
If you can overbuild your Solar power systems enough to reduce the long-term storage requirement, maybe go ahead and store a heavier hydrocarbon like ethanol or kerosene that is less leak-prone. Kerosene is a good choice because it is "green" jet fuel. IMO it will be quite a while before we have a viable alternative to jet turbines, and even longer before we can retire the jet fleet. Given the infrastructure to produce "green" jet fuel, using it with distributed kerosene-fueled turbo generators is viable. Again, here in California (in Oakland) one of our power plants uses these, albeit with fossil kerosene. They are basically slightly-modified jet engines.
Yes, but the leak is plugged now.  And I agree, it's solar+wind+storage.  Developing storage for computers, and then for cars, has gone a long way in making chemical batteries a good candidate for storage, as there are no intermediate conversion steps, except for some transformation losses and transport costs.
If Americans use 5 kW of power on average (taking into account gains in energy use by converting everything to electrical) then a one day storage is 24 x 5 = 120 kWh of storage.  Three days is 120 x 3 = 360 kWh.  So 4 Tesla battery packs.  That's about 40 kg of lithium per person, and about 4 tonnes of other stuff, since the lithium is actually a small fraction of the mass of a lithium battery.  Seems quite doable.
Title: Re: Solar Power Satellites
Post by: DanClemmensen on 02/04/2023 06:22 pm

Europe's 60-day supply of NG is stored primarily underground in depleted oil and NG fields. I have no insight into leaks there. Here in California, we had a huge leak from such a field
    https://en.wikipedia.org/wiki/Aliso_Canyon_gas_leak
and by "huge", I mean an appreciable percentage of California's annual methane leakage.  I have no confidence in distributed storage of methane, but that's a personal opinion.

Closing the loop, again: SBSP will not compete economically it we have viable long-term "green" energy storage.
If you can overbuild your Solar power systems enough to reduce the long-term storage requirement, maybe go ahead and store a heavier hydrocarbon like ethanol or kerosene that is less leak-prone. Kerosene is a good choice because it is "green" jet fuel. IMO it will be quite a while before we have a viable alternative to jet turbines, and even longer before we can retire the jet fleet. Given the infrastructure to produce "green" jet fuel, using it with distributed kerosene-fueled turbo generators is viable. Again, here in California (in Oakland) one of our power plants uses these, albeit with fossil kerosene. They are basically slightly-modified jet engines.
Yes, but the leak is plugged now.  And I agree, it's solar+wind+storage.  Developing storage for computers, and then for cars, has gone a long way in making chemical batteries a good candidate for storage, as there are no intermediate conversion steps, except for some transformation losses and transport costs.
If Americans use 5 kW of power on average (taking into account gains in energy use by converting everything to electrical) then a one day storage is 24 x 5 = 120 kWh of storage.  Three days is 120 x 3 = 360 kWh.  So 4 Tesla battery packs.  That's about 40 kg of lithium per person, and about 4 tonnes of other stuff, since the lithium is actually a small fraction of the mass of a lithium battery.  Seems quite doable.
I love to discuss this stuff, but we are getting very far off topic, so I'll quit. The only relevance here is that a lack of long-term storage (i.e., more than a month) might justify SBSP, but there are multiple ways to implement long-term storage.
Title: Re: Solar Power Satellites
Post by: mandrewa on 02/04/2023 06:48 pm

I've thought along the same lines.  But that raises an interesting question.  Over 80% of the world's solar cells are being made in China.  Part of the reason that the current greenhouse emissions from solar cells are so high is because China burns a lot of coal in the process of making those solar cells.

So why don't the Chinese use their solar cells to make the energy to make solar cells?

The answer must be that it is a question of cost.  Getting energy from coal is cheaper than getting it from solar cells.  And cost is the main thing they care about in China.

And that's the problem in a nutshell, and the reason that global greenhouse gas emissions are steadily increasing.  It's not just China but it's most of the world for which cost is what decides what will be built.

To really make a difference we have to have energy technologies that are cheaper than coal.  It's obvious that solar power satellites are going to start off being more expensive.  But it's a baby-in-the-bathwater situation.

Meanwhile we do know that coal is cheaper than solar cells or windmills because China dominates the production of both of these things, and if either was cheaper than coal that would be what they were using.
Because they are not there yet.
China has 3000 GW of installed power, but only 300 GW of solar power.  So they use coal, and studies attribute that coal to the solar panel production.

I would think it would be relatively easy for the companies making solar cells to deploy their solar cells next to the factory to make the energy to make the solar cells. This is such an obvious thing to do that it is striking that it is not being done.

There is no large scale carbon free steel production for the moment in China, or anywhere in the world for that matter.

Yes. And one of the reasons for that is that when we say that a certain number of solar cells is equal to 300 GW that's quite a simplification of a complicated reality.  Solar cells produce a curve of output that varies from day to day, from month to month, and, quite dramatically, from hour to hour.  This number, 300 GW from solar cells, is not the same thing from a power perspective, as 300 GW from coal. The details and limitations of solar cells versus other power plants are a huge part of the issue when it comes to making steel.

As the environmental damage of coal is not counted in cost, coal usually wins on cost.  However, solar has started being better than coal even on base cost levels.  So it's really a matter of time until the Chinese build up enough solar and wind to displace the coal.  The more they build, the better the numbers get.  So the answer is that they haven't had the time yet.

Most gains for solar power satellites can be applied to Earth.  The fundamental problems with space solar are:

The single biggest advantage of solar power satellites, to my mind, is the absence of a need for low-cost green energy storage.

Quote
-Much of it is lost in transmission, negating the availability advantage.
-The infrastructure required is large and hard to scale up to.  In particular, ground level antennas are huge, since power density of the beam is limited to avoid cooking birds and stray people.

Yes.  But this has already been taken into account.  The proposed microwave receiving antennas are designed to be people and animal safe.  In fact it may be possible to combine farms with microwave receiving antennas.

Quote
-There are a number of unknown costs from maintenance that might sink the concept.
-Launching all that materials from Earth will eventually damage the atmosphere somewhat.

That's going to be part of the greenhouse emissions cost of solar power satellites.  We can probably start to estimate that now.  How many solar cell satellite modules can a Starship launch and at what cost in greenhouse gas emissions?

Quote
-It's an infrastructure heavy system, that requires central 'plants', the rectenna arrays, and a large distribution system.  Home produced solar power destroys this centralized model by providing absurdly cheap electricity for much of the day.  So the infrastructure costs become too high to maintain, destroying the economical model.  This is not a solved problem for most utilities and will only get worse.

Here's an interesting example of someone actually doing this, ie. a practical, off-grid house.  See https://www.youtube.com/watch?v=f1ZyZNRYezA .

He's in an almost ideal situation, but nonetheless, this system cost this technically savvy and knowledgeable user -- this is the second time he's built a solar power system for his house -- approximately $130,000, and they still have to carefully plan what they do, ie. his wife can only do laundry at certain times and with coordination with him, and there is still one month of the year where they are getting their power from a backup diesel generator.
Title: Re: Solar Power Satellites
Post by: zubenelgenubi on 02/04/2023 07:08 pm
Moderator:
Discussion is running 🏃‍♂️ far afield from the topic: Solar Power Satellites. 🛰
⚠️
Stay on topic.
Title: Re: Solar Power Satellites
Post by: Asteroza on 02/06/2023 12:42 am
SPS is not 100% 24/7/365 due eclipsing though. You'll need to cover for the ones that enter shadow once a year, which has implications for transmitter design being able to split beams to multiple rectennas, or sufficient ground transmission capacity to backfill rectennas that go dark, or enough ground storage. The general image has always been one SPS be ground rectenna but I think the engineering consensus was phased array beam splitting was not only doable, but desirable for some aspects. Having multiple beams on a single rectenna might complicate things though.
Title: Re: Solar Power Satellites
Post by: mandrewa on 02/06/2023 01:30 am
SPS is not 100% 24/7/365 due eclipsing though. You'll need to cover for the ones that enter shadow once a year, which has implications for transmitter design being able to split beams to multiple rectennas, or sufficient ground transmission capacity to backfill rectennas that go dark, or enough ground storage. The general image has always been one SPS be ground rectenna but I think the engineering consensus was phased array beam splitting was not only doable, but desirable for some aspects. Having multiple beams on a single rectenna might complicate things though.

Well the Caltech design, which is just one possible design for a solar power satellite, can change the aim of the satellite in micro fractions of second.  In fact, you could have one Caltech-type solar power satellite sending microwaves to multiple microwave receiving antennas at the same time.

So if that design or something related to it, turned out to be the best solution, then all we need is to have multiple solar power satellites in the sky to solve this problem of an occasional eclipse.  Nearby solar power satellites could redirect some of their power to the antenna that normally gets power from the solar power satellite that was in eclipse.
Title: Re: Solar Power Satellites
Post by: lamontagne on 02/06/2023 01:38 am
SPS is not 100% 24/7/365 due eclipsing though. You'll need to cover for the ones that enter shadow once a year, which has implications for transmitter design being able to split beams to multiple rectennas, or sufficient ground transmission capacity to backfill rectennas that go dark, or enough ground storage. The general image has always been one SPS be ground rectenna but I think the engineering consensus was phased array beam splitting was not only doable, but desirable for some aspects. Having multiple beams on a single rectenna might complicate things though.
You would expect to have the ground stations connected for multiple redundancy, so any one of them can be off at one time.  Just for the US there will have to be about 1000 of these to provide the required power, at 1GW each.  Perhaps 10 000+ long term for the entire planet.  Even if they are significantly larger, at a few GW each, that still means many hundreds only for the US.
Title: Re: Solar Power Satellites
Post by: zubenelgenubi on 02/09/2023 07:43 pm
Moderator:
Discussion is running 🏃‍♂️ far afield from the topic: Solar Power Satellites. 🛰
⚠️
Stay on topic.
Continuing off-topic-ness.
Thread trimmed.🔪✂️
Title: Re: Solar Power Satellites
Post by: mandrewa on 02/13/2023 11:41 am
Blue Origin has developed a process to make solar cells (plus oxygen, iron, aluminum, and silicon) from lunar regolith. 

Quote:

Our novel process fabricates solar cells, including cover glass, using only products from our reactor. These long-lived cells resist degradation caused by radiation on the Moon. Here we show silicon melting as well as the thin-layer deposition that makes solar cells.

For protection from the harsh lunar environment, solar cells need cover glass; without it, they would only last for days. Our technique uses only molten regolith electrolysis byproducts to make cover glass that enables lunar lifetimes exceeding a decade.

Because our technology manufactures solar cells with zero carbon emissions, no water, and no toxic ingredients or other chemicals, it has exciting potential to directly benefit the Earth.


from https://www.blueorigin.com/news/blue-alchemist-powers-our-lunar-future/
Title: Re: Solar Power Satellites
Post by: Greg Hullender on 05/29/2023 02:57 pm
A new article about Japan's efforts to put up Solar Power Satellites. (https://asia.nikkei.com/Business/Science/Japan-to-try-beaming-solar-power-from-space-in-mid-decade)

Quote
Japan to try beaming solar power from space in mid-decade

The group plans an experiment around fiscal 2025 to see if power can be transmitted from outer space to the ground. Small satellites will be used to send it to ground-based receiving stations from hundreds of kilometers away.
I think this is the first time they've given a date to try to transmit power from space to the ground. Everything in the past was either point-to-point on Earth or point-to-point in space.
Title: Re: Solar Power Satellites
Post by: Asteroza on 05/29/2023 11:39 pm
https://virtussolis.space/ (https://virtussolis.space/)

Another outfit, baselining Starship parts delivery and some sort of MEO altitude to try to get 50% duty cycle per sat (looks like a tundra orbit style constellation).

John Bucknell is with them, so this might be interesting. Guess he isn't running with his NTTR rocket for now...
Title: Re: Solar Power Satellites
Post by: Greg Hullender on 06/03/2023 06:13 pm
In a First, Caltech's Space Solar Power Demonstrator Wirelessly Transmits Power in Space (https://www.caltech.edu/about/news/in-a-first-caltechs-space-solar-power-demonstrator-wirelessly-transmits-power-in-space?fbclid=IwAR1SCJAhwlkMDqDi5QDxXPXen9C_HbbXjf9JdBwJEW6GzNWpI8DV6d-bwHs)
Quote
A space solar power prototype that was launched into orbit in January is operational and has demonstrated its ability to wirelessly transmit power in space and to beam detectable power to Earth for the first time.

This looks promising.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 06/03/2023 09:38 pm
&lt;a href="https://www.caltech.edu/about/news/in-a-first-caltechs-space-solar-power-demonstrator-wirelessly-transmits-power-in-space?fbclid=IwAR1SCJAhwlkMDqDi5QDxXPXen9C_HbbXjf9JdBwJEW6GzNWpI8DV6d-bwHs"&gt;In a First, Caltech's Space Solar Power Demonstrator Wirelessly Transmits Power in Space&lt;/a&gt;
Quote
A space solar power prototype that was launched into orbit in January is operational and has demonstrated its ability to wirelessly transmit power in space and to beam detectable power to Earth for the first time.

This looks promising.
These smaller complete solar power satellites would allow power capabilities to grow with each launch. Unlike large single satellite which needs to be assembled by multiple launches before generating power ie revenue.

Instead of large GEO stations may end up with LEO constellation like Starlink. Powerlink?
Title: Re: Solar Power Satellites
Post by: mandrewa on 06/03/2023 09:50 pm
&lt;a href="https://www.caltech.edu/about/news/in-a-first-caltechs-space-solar-power-demonstrator-wirelessly-transmits-power-in-space?fbclid=IwAR1SCJAhwlkMDqDi5QDxXPXen9C_HbbXjf9JdBwJEW6GzNWpI8DV6d-bwHs"&gt;In a First, Caltech's Space Solar Power Demonstrator Wirelessly Transmits Power in Space&lt;/a&gt;
Quote
A space solar power prototype that was launched into orbit in January is operational and has demonstrated its ability to wirelessly transmit power in space and to beam detectable power to Earth for the first time.

This looks promising.
These smaller complete solar power satellites would allow power capabilities to grow with each launch. Unlike large single satellite which needs to be assembled by multiple launches before generating power ie revenue.

Instead of large GEO stations may end up with LEO constellation like Starlink. Powerlink?


Solar Power Satellites have to be a certain minimum size to work at all.  This tiny demo, which seems to be doing well, is very far from that. 

The Caltech plan, which this demo is a part of, is to assemble a solar power satellite from a great many modules.  I'm not sure how they self-assemble and connect together, but the end result is a large light-weight flat surface.  It's not particularly strong.  And there are no rigid beams supporting it. 

It's probably rippling all the time from various gravitational influences.  The individual modules, which are a little larger than your hand, would know their position in space and would be continuously electronically shifting their aim to target a microwave receiving antenna on Earth.

The Solar Power Satellite team from Caltech had planned to use the Atlas V to launch these modules.  And those launches would have been a considerable part of the cost of the project.

I wonder of course what the Starship could do for this.
Title: Re: Solar Power Satellites
Post by: john_bucknell on 06/05/2023 11:34 am
https://virtussolis.space/ (https://virtussolis.space/)

Another outfit, baselining Starship parts delivery and some sort of MEO altitude to try to get 50% duty cycle per sat (looks like a tundra orbit style constellation).

John Bucknell is with them, so this might be interesting. Guess he isn't running with his NTTR rocket for now...

Decent overview of current activity.  You can follow us on LinkedIn or on our blog.

https://www.nextbigfuture.com/2023/05/global-race-for-space-based-solar-power.html
Title: Re: Solar Power Satellites
Post by: CameronD on 06/13/2023 07:57 am
Scientists beam solar power to Earth from space for first time ever

A space solar power prototype has demonstrated its ability to wirelessly beam power through space and direct a detectable amount of energy toward Earth for the first time. The experiment proves the viability of tapping into a near-limitless supply of power in the form of energy from the sun from space.

Because solar energy in space isn’t subject to factors like day and night, obscuration by clouds, or weather on Earth, it is always available. In fact, it is estimated that space-based harvesters could potentially yield eight times more power than solar panels at any location on the surface of the globe.

The wireless power transfer was achieved by the Microwave Array for Power-transfer Low-orbit Experiment (MAPLE), an array of flexible and lightweight microwave power transmitters, which is one of the three instruments carried by the Space Solar Power Demonstrator (SSPD-1).

https://www.space.com/space-solar-power-satellite-beams-energy-1st-time


I note they say a "detectable" amount.. but it sounds like a first step.
Title: Re: Solar Power Satellites
Post by: Vultur on 06/13/2023 03:46 pm
Obviously a long way from practical use, but still ... this is *so cool* !!!!

I wish someone could convince Elon Musk to take another look at space solar power. I think there's a real role for it for nations with really poor Earth solar energy potential (like much of Europe, especially cloudy + high latitude Northern/Western Europe).
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 06/13/2023 09:23 pm


Obviously a long way from practical use, but still ... this is *so cool* !!!!


Have to start somewhere. Manned flight started with Kittyhawk and now look where we  are. People that say SSP is uneconomic are thinking kittyhawk not A380.

Title: Re: Solar Power Satellites
Post by: Vultur on 06/14/2023 01:39 pm
Have to start somewhere.
Oh, certainly.

I wonder if they already have a follow up planned?
Title: Re: Solar Power Satellites
Post by: Twark_Main on 06/16/2023 03:03 am
The fact that we're crowing so loudly about "detectable" levels of energy transmission just goes to show how far off (some would say impossible) SBSP is.

It's fine for niche spaceflight or terrestrial applications, but competition for mass scale ground-based solar power it is not.
Title: Re: Solar Power Satellites
Post by: CameronD on 06/16/2023 03:23 am
The fact that we're crowing so loudly about "detectable" levels of energy transmission just goes to show how far off (some would say impossible) SBSP is.

It's fine for niche spaceflight or terrestrial applications, but competition for mass scale ground-based solar power it is not.

Oh, don't be such a realist.  Current levels excitement over the practical near-impossibilities of SPS isn't really all that different to that effused over Space Elevators and Hypersonic Travel in recent years.  ::)

As the saying goes: If you aim at nothing, you're sure to hit it.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 06/16/2023 04:22 am
The fact that we're crowing so loudly about "detectable" levels of energy transmission just goes to show how far off (some would say impossible) SBSP is.

It's fine for niche spaceflight or terrestrial applications, but competition for mass scale ground-based solar power it is not.

Oh, don't be such a realist.  Current levels excitement over the practical near-impossibilities of SPS isn't really all that different to that effused over Space Elevators and Hypersonic Travel in recent years.  ::)

This isn't the ringing endorsement you think it is.  ;)

As the saying goes: If you aim at nothing, you're sure to hit it.

Nice quote, but it's a false dichotomy. The actual decision here isn't "SBSP or nothing."
Title: Re: Solar Power Satellites
Post by: edzieba on 06/16/2023 07:39 am
The fact that we're crowing so loudly about "detectable" levels of energy transmission just goes to show how far off (some would say impossible) SBSP is.
The fact that we're crowing so loudly about "landing" a rocket stage in the ocean and it exploding on impact just goes to show how far off (some would say impossible) stage reuse is.

SBSP is not gong to leap fully-formed from nothing to a multi-megawatt generation system in one go. Testing spacecraft elements, control systems, system architecture, and environmental modelling (e.g. beam attenuation and deflection from real-world weather rather than atmospheric simulations) and so on at subscale before committing to a megaproject is just good practice.
Title: Re: Solar Power Satellites
Post by: InterestedEngineer on 06/16/2023 03:13 pm
what if they biggest customer of solar power satellites is other space based installations, and not the local planet?
Title: Re: Solar Power Satellites
Post by: redneck on 06/16/2023 10:52 pm
what if they biggest customer of solar power satellites is other space based installations, and not the local planet?

That's the key point. A fairly modest SPS beaming to other assets that wouldn't have to carry as much power generation gear. Especially for intermittent requirements. Like in space manufacturing tests that need a lot for a short time. Microwave receiver of modest size instead of a much larger solar array. Relatively low orbit for the SPS to keep beaming distance down and rectennas as small as possible. Or possibly a more coherent beam if it can get around the weapons restrictions.
Title: Re: Solar Power Satellites
Post by: Greg Hullender on 06/17/2023 02:32 am
what if they biggest customer of solar power satellites is other space based installations, and not the local planet?
Hard for me to see why an installation wouldn't rather have its own solar panels. Unless we're talking about parts of space that don't have a sun. ;-)
Title: Re: Solar Power Satellites
Post by: Nomadd on 06/17/2023 09:02 am
 Every working satellite in the sky is beaming detectable amounts of power to the surface.
 Is there actually something new here? Did this test show anything you couldn't have gotten using basic antenna specs?
Title: Re: Solar Power Satellites
Post by: redneck on 06/17/2023 10:32 am
what if they biggest customer of solar power satellites is other space based installations, and not the local planet?
Hard for me to see why an installation wouldn't rather have its own solar panels. Unless we're talking about parts of space that don't have a sun. ;-)

Do you mean the night parts of the orbit in LEO? If a lot of continuous power is needed for some reason, it might make sense to buy power from an SPS constellation in a higher orbit. It comes back also to size, weight, and complexity of your own panels vs whatever receiving equipment would be needed.  It seems to me that fairly high concentrations could be beamed relative to sunlight which would considerably reduce collection requirements for a free flier.

That would be for short term research sats though. For long term and consistent power requirements, I think one would want their own panels. There was a discussion some years back of solar panels negatively interacting with sensitive microgravity experiments. It was thought by some that an omnidirectional rectenna would be an advantage with the power supplied by a different sat flying in formation.
Title: Re: Solar Power Satellites
Post by: edzieba on 06/17/2023 10:59 am
Is there actually something new here? Did this test show anything you couldn't have gotten using basic antenna specs?
- Deployment of the flexible substrate array
- Demonstration of space-to-space power transfer (turns out nobody had actually tried, though nobody would doubt it would work)
- Demonstration of phased-array beamsteering for power delivery in orbit
- Performance characterisation of the behaviour of their flexible array design (i.e. does it match the modelled behaviour)

Basically taking stuff that works on earthbound test stands, and testing it in the real working environment after being bounced around on a rocket launch (https://www.caltech.edu/about/news/in-a-first-caltechs-space-solar-power-demonstrator-wirelessly-transmits-power-in-space).
Title: Re: Solar Power Satellites
Post by: Greg Hullender on 06/17/2023 02:54 pm
what if they biggest customer of solar power satellites is other space based installations, and not the local planet?
Hard for me to see why an installation wouldn't rather have its own solar panels. Unless we're talking about parts of space that don't have a sun. ;-)
Do you mean the night parts of the orbit in LEO? 
No, I was trying to make a joke. :-( Sort of like the proposed mission to land on the sun. (It's going to go at night.)

Seriously, the satellites intended to provide power to the Earth send a deliberately diffuse beam so that it wouldn't hurt anything standing in the way, and, hence, they need rather large arrays to capture the power. It's hard to see the benefit to a satellite if it has an array of power antennae bigger than the equivalent solar panels.

Of course a power satellite dedicated to supporting in-space customers would probably use a much more intense beam, but, as far as I know, no one is looking at that. It's easy to see how it could end up being an effective anti-satellite device. Anyway, such a thing should probably beam visible light so the target mission could simply use standard solar panels to pick it up.

I suppose there might be some value in beaming power to a distant probe--beyond Jupiter's orbit--to avoid the need for nuclear power. I visualize a vehicle that had solar panels that provided maintenance power even without external support. Something in an elliptical orbit that only operated its instruments 5% or 10% of the time, using battery power. And which recharged the batteries when the solar power station beamed a laser at it. So a single power station might support ten or twenty different missions at one time.

However, I'm not sure how badly the power would drop off with distance, and, in any event, it sure seems like a lot of work just to avoid nuclear power.
Title: Re: Solar Power Satellites
Post by: redneck on 06/17/2023 06:12 pm
what if they biggest customer of solar power satellites is other space based installations, and not the local planet?
Hard for me to see why an installation wouldn't rather have its own solar panels. Unless we're talking about parts of space that don't have a sun. ;-)
Do you mean the night parts of the orbit in LEO? 
No, I was trying to make a joke. :-( Sort of like the proposed mission to land on the sun. (It's going to go at night.)

 laser at it. So a single power station might support ten or twenty different missions at one time.

However, I'm not sure how badly the power would drop off with distance, and, in any event, it sure seems like a lot of work just to avoid nuclear power.

Your mention of supporting multiple units from one power source made me think of the large numbers of smaller rideshare sat going up now. Perhaps an over watch sat supplying power to short termers doing research. If and only if the receiving equipment was considerably less than the dedicated solar panels. Less in cost, mass, and complexity for limited budget missions.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 06/17/2023 06:37 pm
what if they biggest customer of solar power satellites is other space based installations, and not the local planet?
Beamed power can be used to push spaceships. Giant lasers which focus on space ships concave mirror(sail). If there is 2nd mirror on power station the photons can bounce back and fore between two mirrors giving lot more thrust. This is Photon Rececycling and has been demostrated in lab. With GW levels of power it is possible to move human space ships between earth and Mars in days. Need another power station in Mars orbit to slow space craft down. With this technology all resources of asteriod belt are in easy reach with no fuel needed.

https://youtu.be/Wol8EU6Rtbk

https://breakthroughinitiatives.org/initiative/3
Title: Re: Solar Power Satellites
Post by: Twark_Main on 06/17/2023 06:40 pm
The fact that we're crowing so loudly about "detectable" levels of energy transmission just goes to show how far off (some would say impossible) SBSP is.
The fact that we're crowing so loudly about "landing" a rocket stage in the ocean and it exploding on impact just goes to show how far off (some would say impossible) stage reuse is.

"It's important to reason from physics First Principles, not by drawing analogies with previous systems." -- the guy who pulled off stage reuse  :)

SBSP isn't progressing nearly as fast as reusable rockets. We have good physics reason (efficiency) and space sustainability reasons (Kessler "MMOD breeder" effect) to believe that SBSP may be never actually become feasible.
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 06/17/2023 06:53 pm


The fact that we're crowing so loudly about "detectable" levels of energy transmission just goes to show how far off (some would say impossible) SBSP is.
The fact that we're crowing so loudly about "landing" a rocket stage in the ocean and it exploding on impact just goes to show how far off (some would say impossible) stage reuse is.

"It's important to reason from physics First Principles, not by drawing analogies with previous systems." -- the guy who pulled off stage reuse  :)

SBSP isn't progressing nearly as fast as reusable rockets. We have good physics reason (efficiency) and space sustainability reasons (Kessler "MMOD breeder" effect) to believe that SBSP may be never actually become feasible.

Space based lasers can be used to deorbit debris, probably must to protect large SBSP structures.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 06/17/2023 07:00 pm


The fact that we're crowing so loudly about "detectable" levels of energy transmission just goes to show how far off (some would say impossible) SBSP is.
The fact that we're crowing so loudly about "landing" a rocket stage in the ocean and it exploding on impact just goes to show how far off (some would say impossible) stage reuse is.

"It's important to reason from physics First Principles, not by drawing analogies with previous systems." -- the guy who pulled off stage reuse  :)

SBSP isn't progressing nearly as fast as reusable rockets. We have good physics reason (efficiency) and space sustainability reasons (Kessler "MMOD breeder" effect) to believe that SBSP may be never actually become feasible.

Space based lasers can be used to deorbit debris, probably must to protect large SBSP structures.

That's just something people say.

I've seen no indication that any solution (including lasers) that tries to clean up debris after it's broken into millions of pieces is going to be remotely economical.

It's far less than a million times harder to deorbit the original satellite before it before it breaks up into debris, so economically that solution wins almost every time.



Due to these cold hard economic realities, in practice what really happens is that lasers are only ever used to deflect valid criticism (not MMOD), and meanwhile all real SBSP proposals just accept this MMOD-breeding erosion as "business as usual," externalizing their pollution onto everyone else.
Title: Re: Solar Power Satellites
Post by: Twark_Main on 06/17/2023 07:11 pm
Let's think about this from the perspective of scaling laws.

SBSP produces power. Lasers to protect that SBSP would use some of that power.

The laser power scales as the MMOD flux. More flux = more laser deflection events needed per second.

So there must be some MMOD flux where 100% of the solar power is used to power the lasers.


Lasers are just a band-aid, not the ultimate solution. You have to rely on more economical means to remove the bulk material, otherwise the lasers just get swamped.
Title: Re: Solar Power Satellites
Post by: edzieba on 06/19/2023 08:37 am
SBSP isn't progressing nearly as fast as reusable rockets. We have good physics reason (efficiency) and space sustainability reasons (Kessler "MMOD breeder" effect) to believe that SBSP may be never actually become feasible.
SBSP and reusable rockets were conceptualised in around the same timeframe (before the first launches of orbital rockets), and both have taken many many decades between "here's a thing that's possible to do" and start of actual serious development work. And both have seen aborted attempts at that development work and travelled down dead-end avenues (e.g. winged flyback stages, laser-based beaming for power transmission).
As with stage reuse, the chief challenges are economic rather than technical: firstly, whether you can make a profit (e.g. reusing stages vs expending them - flightrate projections change this equation dramatically) and secondly whether you can convince someone to up-front you the cash to develop the system. The latter is typically the harder task.


As for the Kessler boogeyman: one only needs to look at Starlink if one wants to find an actual rather than theoretical sky to worry about falling - incidentally enabled directly by reusable rockets.
Title: Re: Solar Power Satellites
Post by: LMT on 06/19/2023 12:04 pm
The laser power scales as the MMOD flux. More flux = more laser deflection events needed per second.

Ignore posted facts, and you post sci-fi clutter.

As we saw, a Perseid destroyed Olympus-1 (https://forum.nasaspaceflight.com/index.php?topic=35013.msg2363335#msg2363335), at 60 km/s.  There's no SSP "laser deflection" solution for even the most obvious and predictable flux.
 
Title: Re: Solar Power Satellites
Post by: Asteroza on 07/17/2023 06:52 am
ESA SOLARIS getting to RFI stage

https://www.leonarddavid.com/wanted-ideas-on-space-based-solar-power/ (https://www.leonarddavid.com/wanted-ideas-on-space-based-solar-power/)

RFI
https://ideas.esa.int/apps/IMT/UploadedFiles/00/f_2673a537ff81d4d3817c469dbe56539b/Request_for_Information_-_Research_Activities_for_Space-Base.pdf?v=1686648213 (https://ideas.esa.int/apps/IMT/UploadedFiles/00/f_2673a537ff81d4d3817c469dbe56539b/Request_for_Information_-_Research_Activities_for_Space-Base.pdf?v=1686648213)

Additional Info
https://ideas.esa.int/servlet/hype/IMT?documentTableId=45087160510006963&userAction=Browse&templateName=&documentId=07ab8ee1283f322118a955afbfc3c2bc (https://ideas.esa.int/servlet/hype/IMT?documentTableId=45087160510006963&userAction=Browse&templateName=&documentId=07ab8ee1283f322118a955afbfc3c2bc)
Title: Re: Solar Power Satellites
Post by: Asteroza on 07/21/2023 05:43 am
Under the SOLARIS research umbrella, ESA studies on a Lagrange point (L1? L2?) SPS called (GE⊕-LPS) built from lunar ISRU as a stepping stone to earth SPS constellations.



Looks sorta like CASSIOPeiA but the helix isn't quite a straight windchime helix, and each "vane" is actually a V shaped solar PV spar with integrated transmitter. Which probably has implications regarding the weird shape as well as the expected point angles.

https://www.esa.int/ESA_Multimedia/Images/2023/07/Lunar_solar_power_satellite (https://www.esa.int/ESA_Multimedia/Images/2023/07/Lunar_solar_power_satellite)

https://nebula.esa.int/content/ge%E2%8A%95-lunar-power-station (https://nebula.esa.int/content/ge%E2%8A%95-lunar-power-station)


The study partner was Astrostrom, but the partner's website shows a very different style of SPS

https://astrostrom.ch/en/GEO-LPS_greater_earth_lunar_power_station.php (https://astrostrom.ch/en/GEO-LPS_greater_earth_lunar_power_station.php)

Title: Re: Solar Power Satellites
Post by: CameronD on 07/21/2023 07:59 am
Under the SOLARIS research umbrella, ESA studies on a Lagrange point (L1? L2?) SPS called (GE⊕-LPS) built from lunar ISRU as a stepping stone to earth SPS constellations.

Looks sorta like CASSIOPeiA but the helix isn't quite a straight windchime helix, and each "vane" is actually a V shaped solar PV spar with integrated transmitter. Which probably has implications regarding the weird shape as well as the expected point angles.

A question from the sceptical:  That thing looks enormous!  How long are PV solar panels expected to last in space? 

Should this design ever move off the computer screen, I'm guessing continuous maintenance would be required.  Robot telehandlers, perhaps??
Title: Re: Solar Power Satellites
Post by: TrevorMonty on 07/21/2023 09:35 am
Under the SOLARIS research umbrella, ESA studies on a Lagrange point (L1? L2?) SPS called (GE⊕-LPS) built from lunar ISRU as a stepping stone to earth SPS constellations.

Looks sorta like CASSIOPeiA but the helix isn't quite a straight windchime helix, and each "vane" is actually a V shaped solar PV spar with integrated transmitter. Which probably has implications regarding the weird shape as well as the expected point angles.

A question from the sceptical:  That thing looks enormous!  How long are PV solar panels expected to last in space? 

Should this design ever move off the computer screen, I'm guessing continuous maintenance would be required.  Robot telehandlers, perhaps??
Given panels are made on moon replacements shouldn't be issue. Would need robotic assembly so same again for maintenance.
Title: Re: Solar Power Satellites
Post by: edzieba on 07/21/2023 12:41 pm
How long are PV solar panels expected to last in space?
AMSAT-OSCAR 7 was not designed for longevity, but its panes are still producing a useful amount of power nearly 50 years later.