Author Topic: Solar Satellite Energy  (Read 12341 times)

Offline stargazer777

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RE: Solar Satellite Energy
« Reply #20 on: 07/14/2007 03:46 PM »
And  the production of the launch vehicle, arrays and infrastructure isn't green neither
Well, you better hope it works or that we achieve a real breakthrough in Fusion real fast.  Otherwise you and several million other Floridians along with the billions of people living in coastal areas around the world are going to be treading water full time once the  melting of the polar caps and the Greenland ice sheet accelerates.

Offline kfsorensen

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RE: Solar Satellite Energy
« Reply #21 on: 07/14/2007 05:59 PM »
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stargazer777 - 14/7/2007  10:46 AM

Well, you better hope it works or that we achieve a real breakthrough in Fusion real fast.  Otherwise you and several million other Floridians along with the billions of people living in coastal areas around the world are going to be treading water full time once the  melting of the polar caps and the Greenland ice sheet accelerates.

Neither fusion nor space solar is needed to stop global warming.  Sufficient uranium and thorium reserves exist to power civilization through the use of breeder reactors for tens of thousands of years.

Offline stargazer777

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RE: Solar Satellite Energy
« Reply #22 on: 07/14/2007 06:06 PM »
Neither fusion nor space solar is needed to stop global warming. Sufficient uranium and thorium reserves exist to power civilization through the use of breeder reactors for tens of thousands of years.
As should be apparent from my earlier posts, I am not opposed to nuclear power generated by fission.  I am sure that fission generated power will be with us for a very long time.  However, there are so many down-sides  to this technology coupled with the massive and potentially dangerous waste disposal issues that no nation has successfully resolved that I don't believe it is the long term answer for the US or Europe let alone the rest of the planet.

Offline kfsorensen

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RE: Solar Satellite Energy
« Reply #23 on: 07/14/2007 06:16 PM »
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stargazer777 - 14/7/2007  1:06 PM

As should be apparent from my earlier posts, I am not opposed to nuclear power generated by fission.  I am sure that fission generated power will be with us for a very long time.  However, there are so many down-sides  to this technology coupled with the massive and potentially dangerous waste disposal issues that no nation has successfully resolved that I don't believe it is the long term answer for the US or Europe let alone the rest of the planet.

Wonderful.  You're halfway there.  Now let's put the waste issue to bed.  A properly-designed nuclear reactor, with complete consumption of the uranium or thorium resource, will produce only fission products as waste.  These fission products (the split nuclei from fission) are highly radioactive but decay very quickly.  Half of all the waste will decay to stable nuclei in about a week.  Within 30 years, it's about 90%.  Within 300 years, the waste has decayed to the level of background radiation, and only a few long-lived nuclides (Zr-93, Tc-99, I-129, Cs-135) remain.

The waste that are of prime concern in today's barely-burned nuclear fuel are neptunium, plutonium, americium, and curium--the so-called transuranics that have intermediate half-lives and elaborate decay chains.  Most of these can be destroyed in a fast reactor, or never created at all when thorium fuel is used.

Powering the entire world on fission energy will produce about 5000 tonnes of fission products per year, a volume that could be easily contained and which will decay rapidly to stability.  Care to take a guess how much CO2 is emitted each year?

Offline kfsorensen

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RE: Solar Satellite Energy
« Reply #24 on: 07/14/2007 06:17 PM »
Here's an old NASA study that shows that the cheapest space power satellite is nuclear-powered, rather than solar-powered.  Kind of a hoot when someone actually runs the numbers...

Commercial Space Transportation Study: 3.8 Space Utilities

Offline stargazer777

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RE: Solar Satellite Energy
« Reply #25 on: 07/14/2007 06:28 PM »
Powering the entire world on fission energy will produce about 5000 tonnes of fission products per year, a volume that could be easily contained and which will decay rapidly to stability. Care to take a guess how much CO2 is emitted each year?
You are a good man and well intentioned, but I can't believe that you are seriously suggesting building hundreds if not thousands of breeder reactors all over the world.  The nuclear proliferation threat issues alone are almost unimaginable.  Add to that the difficulty in safely handling such reactors even in technologically advanced nations -- believe me when I say that this cure is worse than the disease.   

Offline kfsorensen

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RE: Solar Satellite Energy
« Reply #26 on: 07/14/2007 06:45 PM »
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stargazer777 - 14/7/2007  1:28 PM

You are a good man and well intentioned, but I can't believe that you are seriously suggesting building hundreds if not thousands of breeder reactors all over the world.  The nuclear proliferation threat issues alone are almost unimaginable.  Add to that the difficulty in safely handling such reactors even in technologically advanced nations -- believe me when I say that this cure is worse than the disease.

Thank you for your kind assessment of my character, but building thousands of reactors is precisely what I am suggesting.  We have thousands of coal plants spewing filth into the atmosphere--they must be replaced with fission if global warming is to be arrested.  Then there is the need to replace hydrocarbons for transportation with electric cars and trains, which will require even more electricity.  Then there is the need for "uplift" of third-world economies to first-world living standards--that will require even more electricity.  I can easily see the need for about 10,000 GW of electrical generation.  If a typical plant is 1 GW, then that's about 10,000 plants.

Producing 1 GW of electricity for a year requires about 1 tonne of fissile material.  A breeder reactor can produce this energy using fertile material (U-238 or Th-232), transmuting it into fissile material (Pu-239 or U-233) during the operation of the reactor.

I will grant that there are more significant proliferation concerns when the breeder operates on the uranium-plutonium fast-spectrum option, but proliferation risks can be nearly eliminated by using the thorium-uranium thermal-spectrum approach, which creates fissile material contaminated by nuclides that make it un-usable for nuclear weapons, but do not compromise its effectiveness in the reactor.

10,000 GW to get off coal and hydrocarbons and uplift the Third World.  That number won't really change whether we're talking space solar, fusion, or fission.

Offline stargazer777

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RE: Solar Satellite Energy
« Reply #27 on: 07/14/2007 07:41 PM »
Thank you for your kind assessment of my character, but building thousands of reactors is precisely what I am suggesting. We have thousands of coal plants spewing filth into the atmosphere--they must be replaced with fission if global warming is to be arrested.
Your character is fine, but your proposed solution would have catastrophic consequences.  There is no disagreement that coal and other fossil fueled power plants must be replaced very soon, but this is not the answer.  The only countries that would endorse this idea are exactly the nations we do not want to have such technology.  In a peaceful world your solution might be reasonable.  However, we don't live in that world.  We live in a world with maniacal dictators desperate for nuclear weapons and religious fanatics like Al Quedea that would do anything to get nuclear material or better yet a fully functioning breeder reactor.  We can never allow this technology to be globally disseminated.  We must find another solution.  Think space solar power.

Offline kfsorensen

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RE: Solar Satellite Energy
« Reply #28 on: 07/14/2007 09:10 PM »
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stargazer777 - 14/7/2007  2:41 PM

Your character is fine, but your proposed solution would have catastrophic consequences.  There is no disagreement that coal and other fossil fueled power plants must be replaced very soon, but this is not the answer.  The only countries that would endorse this idea are exactly the nations we do not want to have such technology.

Perhaps we need to make sure we are on the same page.  If you are talking about fast breeder reactors that convert uranium-238 into weapons-grade plutonium-239 and are cooled by liquid sodium, then I would tend to agree with you.

However, the liquid-metal fast breeder reactor (LMFBR) pursued by so many nations around the world does not represent the only (or even the best) breeder reactor concept.  And as far as "keeping" the technology to ourselves, it's a bit too late for that.  The technology to build LMFBRs has been widely disseminated and detailed information is available on public websites around the world.  Apparently Al Qaeda isn't feeling as optimistic about LMFBRs as some might worry.

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stargazer777 - 14/7/2007  2:41 PM

In a peaceful world your solution might be reasonable.  However, we don't live in that world.  We live in a world with maniacal dictators desperate for nuclear weapons and religious fanatics like Al Quedea that would do anything to get nuclear material or better yet a fully functioning breeder reactor.  We can never allow this technology to be globally disseminated.

This is why thorium breeders are so compelling.  The process of turning thorium into energy involves inevitable contamination with uranium-232, which makes the resulting fissile material worthless for nuclear weapons.  Witness how many operational nuclear weapons utilize uranium-233....none.  Despite the abundance of thorium around the world.

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stargazer777 - 14/7/2007  2:41 PM

We must find another solution.  Think space solar power.

I've spent an awful lot of time thinking and researching space solar power, only to discover, as most serious researchers in the field do, that it doesn't hold water.  Space solar power is not the answer, for so many reasons that won't yield.  But that's okay.  There's an answer right here on earth, a gift from supernovas five billion years ago: thorium.

Offline TyMoore

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RE: Solar Satellite Energy
« Reply #29 on: 07/16/2007 08:52 AM »
Enough thorium exists on this planet to power us for thousands of years. Creating fast spectrum, deep burn reactors such as the bismuth cooled liquid metal reactors, will elimate most of the residual transuranics (neptunium, plutonium, americium;) reprocessing will create fresh fuel stocks;  weapons grade materials can be easily downblended and burned up in the fuel stocks--adding a perfectly good energy resource. Fission product seperation and storage will be much, much easier than the 1 million year plus storage times proposed by the Department of Energy for the Yucca Mountain Complex. However, it should be perfectly good for a couple of centuries or even 500 years for high level fission fragment storage. Who knows, if we store enough in one repository, we may even be able to extract some of the decay heat and use that for power generation as well!

I am particularly fond of gas cooled, pebble bed reactors because of the high efficiency Brayton gas turbine cycle can be used to more or less directly convert the heat energy into electricity. Moreover,  a gas cooled pebble bed reactor system can be sized to be modular, intrinsically safe (no melt downs or explosions) and can use an air ejector system for plant cooling instead of warming river water (creating a thermal plume harmful to fish!)

On the point of proliferation, I must say this: proliferation has already happened despite everyone's best efforts. The nuclear genie is out of the bottle and cannot ever go back in. The bad guys already have nuclear materials--the question is how much, and what kind, and can they assemble it into a weapon. North Korea apparently detonated a rather sophisticated device despite the world's best efforts to prevent it...and what happens when Iran does the same?

We can't be afraid of nuclear energy. We must embrace it for what it is: a potentially very clean and plentiful energy source that can last for a long time. If we do it right, we can have nuclear power stations that will never have a serious accident--nothing like Chernobyl not so long ago...
If we accept nuclear power as a long term energy solution we can shift our energy production away from fossil fuels--and if Global Warming is indeed as big of a problem as advertised, well then getting away from carbon dioxide emissions is a very good thing. Nuclear weapons proliferation is a danger--very true--and it does involve a finite amount of risk. However, if the majority of the countries stick together and take leadership to develop the technologies and infrastructure needed to create plentiful nuclear fission power, the countries wanting to obtain nuclear weapons will definately be in the minority. And not only will they be outnumbered, but the sheer weight of the capability of global nuclear retalitiatory force will deter any nations from committing nuclear weapons to battle, or from sponsoring terrorist organizations wishing to use nuclear weapons in terrorist attacks.

I think what I am trying to say is that with this strategy, nations like Iran wishing to pursue nuclear energy can thus "put up or shut up." Overall I feel the threat to humanity as a whole is much less from such a global approach to nuclear power, than from the resultant pollution caused by massive combustion of fossil fuels around the globe. And did I mention that we might even avoid an eventual global "Oil War" by pursuing nuclear power in a big way? Food for thought!

Offline stargazer777

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RE: Solar Satellite Energy
« Reply #30 on: 07/17/2007 06:19 AM »

I can't let the discussion on this thread end on this unfortunate note.  

First, there are many first rate thinkers that believe the promise of solar energy from space is real -- not imaginary -- something that is clearly attainable within our lifetimes, and which has the potential to profoundly change for the better the world we live in.  At the end of this post I will list a number of recent studies and articles supporting this proposition.  I am sorry, but the fact that you don't see this, Vanilla, doesn't mean it isn't true.

Second, while I share the hope that nuclear power, in some form, will be a significant part of the energy solution, at least in the medium term, the course of action you have recommended is at best profoundly naive and grossly underestimates both the political complexities and the tremendous risk that the rapid and wholesale dissemination of this technology around the world would pose.  You may brush off the risk of nuclear proliferation, but believe me no serious person in the government of any major power would do so and neither would they sanction a policy that would amount to a suicide pact with hostile or unstable governments and international terrorists.  Nuclear proliferation is a problem and we clearly haven't been able to completely block it, but the course of action you advocate would blow the dam completely and pose an unconscionable risk for every developed nation and more broadly the entire population of this planet.

If you really want to help save the planet then lets work on a solution that would leave it, and its population, alive and intact after it is implemented.  If your argument against solar power is purely economic, then realize that we can, and rapidly changing circumstances due to rising energy costs and the worsening environmental situation inevitably will, dramatically change the rules of that game.  A commitment by the  US and other developed nations to launch a program equivalent to the Manhattan Project to develop a land based and space based solar power infrastructure would have a hugely beneficial impact not simply on the global warming crisis but also place us on the path to being able to provide clean and eventually unlimited power to every nation on the planet.  No more OPEC, no more depending on unstable and erratic Third World nations, and no mushroom clouds in the bargain.  And, of course, creation of the space based solar power infrastructure would have the added benefit that it would permanently put the human race in the space business and place us firmly and irrevocably on the path of being a space faring civilization.

As the Chinese proverb says, "A journey of a thousand miles begins with a single step."  Time to get moving!

 


Offline TyMoore

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RE: Solar Satellite Energy
« Reply #31 on: 07/17/2007 08:47 AM »
I think you misunderstood me. I wasn't arguing against solar power satellites at all.  I am beginning to learn that the economics of their operation is a lot more complicated than I originally thought. There are also some very good and legitimate environmental concerns regarding the beaming of power to the ground from solar power sattelites: the large rectenna areas needed on the ground to couple the necessary power to the grid; and the long term effects of being bathed in low level microwave rf bothers me. One sattelite maybe isn't too bad, now multiply that by perhaps 700-800 clustered over the landmasses all around the equator--large parts of the Earth are going to be bathed in microwave rf--like it or not. This is a personal concern of mine--so much so that I have even thought of using intermediate relay stations in lower orbit that intercept the main power beams at a tangent and then couple the resultant power to the ground using near infrared lasers--not terribly efficient but possibly doable. Economically doable--I have no idea...I know one thing for sure, without tapping the mineral resources of the near earth asteroids, such a construction project will never be feasible. It is not cost effective to launch 700*100,000 tons = 70 million tons of material into Geosynchronous Orbit from the Earth's surface using conventional rockets. The basic material must come from elsewhere--otherwise the energy cost is prohibitive.

A long term application of a thorium-breeder cycle is possible. And the fuel stocks can last for thousands of years--centuries at the least. Deep burning the reactors will burn up most of the actinides. And storing the fission products will only require centuries and not hundreds of millenia.

On the issue of proliferation, I can only say this: proliferation is already out there. Everywhere! Every decent college library worth its salt will have books containing the essential core information for creating nuclear technology...any nation on the planet with the technical will can do it. And the basic differential equations describing the percolation of neutrons through the core of a nuclear reactor also describe what happens in the core of a nuclear bomb. The same physics applies. So any nation capable of creating a nuclear power program is also capable of creating a nuclear bomb program. The technologies are closely related. One of the greatest secrets involving nuclear weapons is this: there are no secrets. Not really. Any industrial nation with reasonably intelligent physicists and engineers can make one. South Africa made one. North Korea tested one. Iran is working on one. Israel (possibly with South Africa.) Pakistan; India. Russia, China, etc. As long as the will is there the result is inevitable: success...

So again, proliferation is kind of a non-issue because it is too late. Proliferation has already happened--it is time to accept that. We desperately need the energy now.

Offline kfsorensen

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RE: Solar Satellite Energy
« Reply #32 on: 07/17/2007 03:49 PM »
I will be happy to continue discussing the demerits of space solar power, and why it doesn't pass the "smell test", but I would also like to discuss the issues that you (stargazer777) have with breeding nuclear reactors as a proliferation risk.  I think this deserves its own thread.  Can we agree on that? (and I will start a thread)

Offline stargazer777

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RE: Solar Satellite Energy
« Reply #33 on: 07/17/2007 04:07 PM »
Yes, I think the nuclear option deserves its own thread and we should confine our interchanges on this thread to the enormous positive potential for solar/solar satellite energy.

Offline khallow

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Re: Solar Satellite Energy
« Reply #34 on: 07/18/2007 03:27 PM »
On the economics point, SPS has to contend with ground-based solar and all these other power sources. I think Sam Dinkin gave very compelling argument against SPS. Given that SPS is roughly four times more efficient over time than the best Earth-based solar (ignoring many relevant issues here), then the SPS has to be no more than four times the cost of an Earth-based solar power system with the corresponding long term power output. And keep in mind that most things that allow you to make a SPS installation cheaper will also allow you to make an Earth-side installation cheaper. My take is that it's going to be a long time before SPS gets below that factor of four cost.
Karl Hallowell

Offline imfan

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Re: Solar Satellite Energy
« Reply #35 on: 07/20/2007 10:38 AM »
I remember reading about other way of producing electricity from solar power in space than by fotovoltaics. It uses parabolical mirror and heat turbine. I think I have even seen it applied on one of Mir-2 projects. The apparent problem is how to ensure fluid circulation  in zero-G conditions, on the other hand there could be som interesting mass tradeoffs with scale since the  turbine is heavy, but mirror can be made of relatively lightweight foil. Also it avoids one of the main fotovoltaics prblems - the efficiency decay by time.

edit: adding some links:
http://www.hq.nasa.gov/office/pao/History/SP-4026/noord36.html
http://en.wikipedia.org/wiki/Solar_power_satellite#Solar_energy_conversion

Offline stargazer777

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Re: Solar Satellite Energy
« Reply #36 on: 07/20/2007 11:16 AM »
On the economics point, SPS has to contend with ground-based solar and all these other power sources. I think Sam Dinkin gave very compelling argument against SPS. Given that SPS is roughly four times more efficient over time than the best Earth-based solar (ignoring many relevant issues here), then the SPS has to be no more than four times the cost of an Earth-based solar power system with the corresponding long term power output. And keep in mind that most things that allow you to make a SPS installation cheaper will also allow you to make an Earth-side installation cheaper. My take is that it's going to be a long time before SPS gets below that factor of four cost.

First, no one is arguing that efforts to build ground based solar power systems should be abandoned.  They certainly should not be.  However Dinkins off the cuff reaction to SPS is hardly an analysis.  The problem with ground based systems is 1) night and, 2) weather (e.g. clouds, snow, etc.).  Many if not most parts of the Northern Hemisphere aren't suitable for large scale solar power installations due to weather.  The same applies to regions in the Southern Hemisphere subject to Monsoon or rainy seasons.  That doesn't mean they can't install solar panels on houses, etc.  It just means that they aren't favorable for the big scale installations we would need to provide consistent power and make a serious dent in the global climate problem and the overall power demand.  Space based systems are always on (power at night and during bad weather) and always operate at maximum efficiency.  

Second, as is previously noted several times in this thread, the ground on which the economics argument is based is shifting rapidly.   The increasing scarcity and cost of fossil fuels, the economic costs of environmental damage and the need to reverse that damage, the need for clean combustion free energy, the need to stop the rapidly advancing global warming  -- these are not just a feel good tree hugger arguments, they are a fundamental change in the way we must view and calculate the cost of energy.   I am not sure where Dinkins got his four times more efficient numbers -- sounds like a WAG to me -- but I don't think he is taking this analysis seriously or should be taken seriously.  I say this particularly in light of his column stating emigration off the planet -- after we ruin the environment -- is the only solution to global warming.  


Offline stargazer777

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Re: Solar Satellite Energy
« Reply #37 on: 07/20/2007 11:23 AM »
I remember reading about other way of producing electricity from solar power in space than by fotovoltaics. It uses parabolical mirror and heat turbine....
Exactly right!  Solar cells aren't the only possible solar power technology in space or on the ground.

Offline khallow

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Re: Solar Satellite Energy
« Reply #38 on: 07/28/2007 07:10 AM »
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stargazer777 - 20/7/2007  4:16 AM

On the economics point, SPS has to contend with ground-based solar and all these other power sources. I think Sam Dinkin gave very compelling argument against SPS. Given that SPS is roughly four times more efficient over time than the best Earth-based solar (ignoring many relevant issues here), then the SPS has to be no more than four times the cost of an Earth-based solar power system with the corresponding long term power output. And keep in mind that most things that allow you to make a SPS installation cheaper will also allow you to make an Earth-side installation cheaper. My take is that it's going to be a long time before SPS gets below that factor of four cost.

First, no one is arguing that efforts to build ground based solar power systems should be abandoned.  They certainly should not be.  However Dinkins off the cuff reaction to SPS is hardly an analysis.  The problem with ground based systems is 1) night and, 2) weather (e.g. clouds, snow, etc.).  Many if not most parts of the Northern Hemisphere aren't suitable for large scale solar power installations due to weather.  The same applies to regions in the Southern Hemisphere subject to Monsoon or rainy seasons.  That doesn't mean they can't install solar panels on houses, etc.  It just means that they aren't favorable for the big scale installations we would need to provide consistent power and make a serious dent in the global climate problem and the overall power demand.  Space based systems are always on (power at night and during bad weather) and always operate at maximum efficiency.


It might not be a great analysis, but it is one. I'd love to see your numbers on this.

Quote
Second, as is previously noted several times in this thread, the ground on which the economics argument is based is shifting rapidly.   The increasing scarcity and cost of fossil fuels, the economic costs of environmental damage and the need to reverse that damage, the need for clean combustion free energy, the need to stop the rapidly advancing global warming  -- these are not just a feel good tree hugger arguments, they are a fundamental change in the way we must view and calculate the cost of energy.   I am not sure where Dinkins got his four times more efficient numbers -- sounds like a WAG to me -- but I don't think he is taking this analysis seriously or should be taken seriously.  I say this particularly in light of his column stating emigration off the planet -- after we ruin the environment -- is the only solution to global warming.  


Factor of 4 comes from 8 hours of direct sunlight equivalent per day plus a hit from atmospheric absorption. The southwest US and northern mexico easily achieve this even with fixed orientation solar cells, for example.

I really don't see the economics of SPS at this point. It requires an expensive space installation and considerable ground resources. The solar panels need a degree of manueverability and are exposed to more degrading radiation than on Earth. Even if one just compares it to Earth-based solar power, it needs to be a lot cheaper than it currently is in order to compete. And SPS would also have to compete with Earth-based fission and wind. Even if putting things in orbit becomes cheap, SPS would have to compete with microwave power relays taking power from one spot on Earth and transfering it to another.

The environmental arguments aren't that compelling. Maybe we're in the midst of rapid (in human terms) global warming, but surely there'd be more evidence if that were the case. As I mention elsewhere in reference to engineering solutions to "solve" global warming, a lot of people are already using global warming as an excuse to push their pet schemes.

Finally, I happen to agree with his column on emigration from Earth. Earth long term isn't a good place for the high population, industrial civilization we have. Keep in mind that if the human race abandons Earth, then environmental harm matters a lot less. It'll recover.
Karl Hallowell

Offline CuddlyRocket

Re: Solar Satellite Energy
« Reply #39 on: 07/28/2007 08:01 AM »
Quote
stargazer777 - 20/7/2007  12:16 PM

First, no one is arguing that efforts to build ground based solar power systems should be abandoned.  They certainly should not be.  However Dinkins off the cuff reaction to SPS is hardly an analysis.  The problem with ground based systems is 1) night and, 2) weather (e.g. clouds, snow, etc.).  Many if not most parts of the Northern Hemisphere aren't suitable for large scale solar power installations due to weather.  The same applies to regions in the Southern Hemisphere subject to Monsoon or rainy seasons.  That doesn't mean they can't install solar panels on houses, etc.  It just means that they aren't favorable for the big scale installations we would need to provide consistent power and make a serious dent in the global climate problem and the overall power demand.  Space based systems are always on (power at night and during bad weather) and always operate at maximum efficiency.
The big economic problem with solar power satellittes is not the cost - people can demonstrate that they will pay for themselves - it's the opportunity cost. What else can we do to produce reliable power supplies with that money?

Even if we limit ourselves to thinking of a single ground-based solar-cell plant capable of producing the same amount of power as a solar-power satellite and as consistently (which requires some kind of buffer storage such as a flow battery), then you get far more solar-power for the given amount of money by building a ground-based plant. This is true for anywhere on Earth (the reason solar-power is not considered for inclement climates is not that it won't work, but that it is more expensive than alternatives), and even at launch costs guesstimated by the space-elevator fraternity!

The economics are why no one in a position to consider giving the go-ahead to a SPS is seriously considering it.

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