Solar windfarms for power in space

[bradjensen3]

Solar cells for use in space are heavy and very expensive.

You can't use them on the Moon's surface unless you have batteries or supercapacitors that can store the generated pwoer for at least 14 days of lunar night each lunar month period.

Since the moon doesn't have a magnetic field, solar wind blows across it all the time, lunar night or lunar day.

Could use use antennas kilometers long and hundreds of meters high as nets or grids, to extract energy from the solar wind?

Could you do something similar with interplanetary vehicles and generate power from it, perhaps using two antennas?

I realize solar wind is very diffuse, even given that one billion tons of solar wind are released by the sun every second.

Perhaps the antenna collectors could be constructed on an interplanetary vehicle as it travels from graphene.  (I don't mean the moon generator.)

Since the ions and electrons are in motion at 300km/second it seems to me there ought to be a way to capture some of that energy.

[Andy DC]

I get the impression you're just making up ideas. This site has a low tolerance for nonsense.

>Could use use antennas kilometers long and hundreds of meters high as nets or grids, to extract energy from the solar wind?<

That is complete nonsense. Please consider thinking before posting.

[Chris Bergin]

Come on now. Sure, sounds wacky to me too, but someone can at least educate as to why...rather than just saying "OMG, nonsense". That helps no one.

But yeah, we don't need many more of these threads. They are bumping down interesting and valid threads.

[ppnl]

Come on now. Sure, sounds wacky to me too, but someone can at least educate as to why...rather than just saying "OMG, nonsense". That helps no one.

But yeah, we don't need many more of these threads. They are bumping down interesting and valid threads.

But he already has four other locked threads.

[Stan-1967]

Do the math for us and show how much momentum is in the diffuse solar wind at the moon.  Assuming one billion tons per second, what the flux ( grams/km^2) at 93,000,000 million miles from the sun?

Do some work with your ideas before posting and asking others to do your work for you.

[bradjensen3]

One of my friends here suggested that I criticize my own ideas so that I don't seem like a complete loon.

1. The number one criticism of using the solar wind as a source for producing an electric current is that it has both positive and negative particles. Protons and alpha particles as well as electrons. Are they evenly distributed through the wind? Could you isolate one or another  to a degree by priming your grid with a voltage? I don't know.

2. The wind starts with a voltage of about 1.5Kv. I don't know what the voltage is when it hits the moon.

3. The 64 dollar question is how diffuse the wind is, which is why I suggested antenna grids that are many square kilometers in extent. i was thinking you could use small newer craters on the moon, and run a tether from the mountains on one rim to the opposite rim, and hang the antenna grid or grids from it.

Judging from the catcalls from the wings, even though the solar wind is strong enough to make solar sailing a possibility (which of course is a matter of momentum, not charge) solar wind must not be dense enough to be of any practical use.

So we are probably stuck with nuclear power with stirling engines for lunar colonies. Those are going to be some big radiators!.

Did you know that the Stirling engine is named after a British clergyman who invented it as a more efficient to the notoriously dangerous steam engine, that was killing people every month at the time he invented it?

It was much less popular than steam, which outlived its early dangerous period, and was in use until about the time the Russian reinvented the rocket equation.

The design is still in use now, and the Russians are pairing it up with nuclear power to drive an ion engine.  At least I read something like that in my recent quest for scientific knowledge.

People seem so skittish about nuclear power.   The obvious answer to NIMBY is don't build powerplants near cities. Build them on oil platform-like structures in the unincorporated shallow parts of the Pacific ocean. Ship indonesian , australian, and maybe american coal to them, then synthesize ultra clean hydrocarbon fuels and export them around the world.  Okay it would be cheaper by far to build them on land, but everywhere is near somebody. Build platforms in areas outside anyone's territorial waters, and raise the flag. It's working for our trading partners!

Did you know that the transmission of oil from source to final user averages out at only 4% of the fuel used in the process? It's much better for long distance than electricity, and you can store vast quantities of energy in storage tanks or underground caverns.

Meanwhile I can't think of anything other than nuclear with steam or more likely stirling engines for power for a permanent colony on the moon.

Nanostructured supercapacitors are coming along pretty fast and might reach the point where they could be paired with solar for lunar use. You would need at least double the solar capacity and 14 times the energy storage.

It should be easy to use old fashioned superconductors on the moon, since the temperature in the shade is near real zero, isn't it?

Another variation on the constant power idea would be to build stirling engines at the lunar poles, and distribute electrical power thru superconducting cables to various parts of the moon, with cables going north or south as the case may be around the radius of the moon.

Or you could build stirling engines in a ring around the poles and do something similar. Each engine would work about half the time.

You could also use stirling engines (for two weeks at a time) anywhere on the surface of the moon. leave the hot side in the sun (and maybe enhance the heat with parabolic reflectors) while leaving the cool side in the shade of say a mylar tent, with big radiattors since there is no convection. (I say the latter not out of a sense that it isn't obvious, but because when I leave out the obvious stuff, some people think it means I don't know it.)

Oh yeah, small craters because they don't have a big hump in the middle of the crater floor, and because the rim mountains haven't eroded much yet. Of course erosion on the moon  is not from wind or water since there isn't any wind and enough water to assist erosion is too hypothetical for this forum.  Of course, if there is free water on the surface of the moon as water vapor, and it collects anywhere there is permanent shade (why wouldn't it - oh wait someone is going to tell me why) then there actually might be some small amount of water-based erosion on the moon, due to the tremendous heating and freezing of the water. 

I meant erosion thru the repeated hot and ultracold periods of the lunar month. (Each period is obviously about two weeks long.) I believe the temperature variation is over 200 degrees celsius or Kelvin, whichever you like better. I'm remembering from the 1960s, I seem to remember 240 degrees but that memory is a little faded. The principle is there, the exact measurements would only matter if you are standing under a looming rock wall on Luna.

Each degree celsius (which I was taught as centigrade by the way) is equal to about 1.8 degrees fahrenheit. 0 degrees celsius is about 32 degrees fahrenheit. That's the slope and intercept of the formula, and I would give you the algebra but I don't want anyone to faint.

Power is measure in Joules, who I think was Newton's butler.

Brad, you ignorant asterisk, stop posting til you've learned enough math to know that everything your post is repetitive, ignorant, and obviously won't work or we would have already thought about it!

There's my first self-critical post. I've talked myself out of most of what I first proposed, brought up other ideas that connect to the idea of generating electrical power on the moon, said obvious things several times, and enjoyed the correspondence from both ends.

This was someone else's idea, I hope no one takes offense at it.

One of the reasons I am so interested in nuclear power in space is because that was what the Russians were using when I was a boy. I guess you need to do that when your integrated circuits are made with vacuum tubes!

I think somebody told me that joke in the early 1970s while I was in the nuclear lab at my small midwestern college which probably would not want you guys to know its name.

(The original texas Instruments integrated circuits were made with discrete components. ) So you could actually make an integrated circuit with vacuum tubes.

Most soviet vacuum tubes wer made in Poland. Poland still makes knockoffs of western vacuum tube designs which are bout by audiophiles looking for that mellow anologue sound.

[meberbs]

One of my friends here suggested that I criticize my own ideas so that I don't seem like a complete loon.

1. The number one criticism of using the solar wind as a source for producing an electric current is that it has both positive and negative particles. Protons and alpha particles as well as electrons. Are they evenly distributed through the wind? Could you isolate one or another  to a degree by priming your grid with a voltage? I don't know.

The answer to the first question, including of why that answer is always true can be found quickly through google.

The answer to the second is no as far as I am aware, and unless you suggest a way, you literally have not suggested a method of generating power, so your idea cannot be evaluated further.

3. The 64 dollar question is how diffuse the wind is, which is why I suggested antenna grids that are many square kilometers in extent. i was thinking you could use small newer craters on the moon, and run a tether from the mountains on one rim to the opposite rim, and hang the antenna grid or grids from it.

Judging from the catcalls from the wings, even though the solar wind is strong enough to make solar sailing a possibility (which of course is a matter of momentum, not charge) solar wind must not be dense enough to be of any practical use.

Again density of the solar wind can be answered by a quick google search. Also the wiki page for solar wind lists the pressure exerted by the solar wind. This pressure is so low, it would not be useful for solar sails. Solar radiation pressure (photons only) is orders of magnitude larger.

There's my first self-critical post. I've talked myself out of most of what I first proposed, brought up other ideas that connect to the idea of generating electrical power on the moon, said obvious things several times, and enjoyed the correspondence from both ends.

Being able to do self-critical stuff helps a lot, it also saves everyone some time if you go through this before you post an idea, since you can get past the first few rounds of objections, and your initial proposal will be better for it.

For the nuclear power in space stuff, I am pretty sure there is already a thread somewhere here to discuss that.

[whitelancer64]

Solar sails do not use the solar wind for propulsion - this is a common misconception. They gain momentum from light hitting the sail. The pressure of the solar wind is about 3 orders of magnitude less than the pressure of light. Light pressure on a square meter of solar sail at 1 AU is about 8 micro (millionths of) Pascals. The pressure of the solar wind on the same square meter of sail at 1 AU would typically be 1-6 nano (billionths of) Pascals.

However, using either to drive a "windmill" would be impossible on the Moon, the force of lunar gravity would greatly overwhelm the comparatively weak pressures.

One last thing - because this greatly bothers me - the Joule is named after James Prescott Joule, a british brewer whose interest in the scientific understanding of electricity and heat was basically a serious hobby intended to allow him to run his brewery more efficiently (but he was a member of the scientific institutions of the era, and his work greatly increased our understanding of the nature of electricity and heat, which is why the Joule is named after him). He was born in 1818 and died in 1889. Isaac Newton was born in 1643 and died in 1727. They lived and died in entirely different eras.

[spacenut]

A solar power farm could be built at L1 or L2 and the power beamed to the lunar surface.  I think most lunar colonies or mining operations will begin at the poles where they can use continuous sunlight for solar power.  Water would be extracted near these locations at any areas of continuous shadow near the poles.  Water will be needed for a colony as well as possible H3 extraction.  Continuous sunlight and continuous shadow near the pole craters, so no nukes would be needed except nearer the equators.  If they do go nukes it will probably be thorium. 

[john smith 19]

High speed particles, high potential differences.

This sounds like a job for Magnetohydrodynamics.

https://en.wikipedia.org/wiki/Magnetohydrodynamics

MHD systems were researched in the 1970s and 1980s. The classic plan was to seed the gas stream from a power plant/rocket with Sodium to make it conductive (note Sodium splits to give Na+ ions and free electrons so, just like the solar wind, the stream is electrically neutral, but still able to generate power) But you needed a nozzle and a big magnet to get the crossed fields IIRC.

So, in principle, you can get electricity generation from a plasma, even though it's strictly electrically neutral. Historically the high plasma densities and flow velocities (some of these systems were basically the back end of a rocket) and aggressiveness of the flow (ionized Sodium is usually only seen inside fluorescent lamps) hammered the hardware.

However whenever I see the idea of "windfarms" or "windmills" in space I can't help thinking of this gadget. 

https://en.wikipedia.org/wiki/Crookes_radiometer

This thing is deceptively simple and AFAIK could be made to work on the Moon, but it would need to be on a massive scale. Note the way turning needs a "Goldilocks" vacuum, good enough to limit drag, not too good to stop it working.

As for nuclear reactors needing huge radiators that only applies in space.
Once you can put the radiator in  a hole filled with fluid (which could just be air), or in direct contact with the lunar regolith, heat transfer no longer depends exclusively on radiation. You can now dump a great deal more heat per unit area.   

My pet peeve. Every "radiator" on earth depends on the convection it can cause in the air around it to dump the massive amounts of heat that they can. If car radiators actually only used radiation to get the job done you would probably end up with either
 a) The whole car body area acting as a part of the radiator (something I believe Howard Hughes briefly tried in the 1930's with his steam car project. It was not a success.  )
b) The engines would be made out of ceramics to run it hot enough to give a temperature difference high enough to keep the radiator size reasonable (No cooling passages, solid lubricant and it adds a whole new meaning to the idea of "Firing it up>"  )

But IRL I suspect that, like Mars, "waste heat" will be just too damm valuable, and at least some will be used by the base for heating during the 2 week night, keeping any food production warm and helping drive any low temperature chemical processes they can find to use it.

However that's OT for this thread.

[bradjensen3]

However, using either to drive a "windmill" would be impossible on the Moon, the force of lunar gravity would greatly overwhelm the comparatively weak pressures.

I'm sorry if anyone thought I was intending to use the mechanical force of solar wind in any way.  I am thinking of using the charges in the solar wind.

https://forum-archive.weavertheme.com/discussion/11303/converting-a-weaver-ii-pro-or-aspen-site-to-weaver-xtreme
One last thing - because this greatly bothers me - the Joule is named after James Prescott Joule, a british brewer whose interest in the scientific understanding of electricity and heat was basically a serious hobby intended to allow him to run his brewery more efficiently (but he was a member of the scientific institutions of the era, and his work greatly increased our understanding of the nature of electricity and heat, which is why the Joule is named after him). He was born in 1818 and died in 1889. Isaac Newton was born in 1643 and died in 1727. They lived and died in entirely different eras.
[/quote]

My posting in reference to Joules was so obviously a joke, I did not for a minute think anyone would take it seriously.   I really thought everyone here would know who Joules was, and that I was making a joke about joules being a common name in fiction for a British butler.

I apologize to anyone who took my talk about Joules and Newton seriously.

[qraal]

There was a design for a Solar Wind Power Satellite that received some attention back in 2010, with some rather outlandish performance claims. Brooks Harrop was the researcher. I spoke to one of the reviewers of the paper, who was rather critical of the claims, so it's an idea that needs far more work to ever be considered a reasonable proposition.

Solar Windmills have been considered for very high power storage. I'm not sure of the exact details, but Paul Birch uses them in several of his papers as power for mass-beam pellet streams. I think the inference is that photon pressure turns the structure(s) up to the desired speed and the energy is stored in moving mass streams. Birch used dynamic compression members to get much higher performance than purely physical structures in tension allowed, thus by-passing materials strength limitations.

[high road]

However whenever I see the idea of "windfarms" or "windmills" in space I can't help thinking of this gadget. 

https://en.wikipedia.org/wiki/Crookes_radiometer

This thing is deceptively simple and AFAIK could be made to work on the Moon, but it would need to be on a massive scale. Note the way turning needs a "Goldilocks" vacuum, good enough to limit drag, not too good to stop it working.

I vividly remember a heated debate between me and my high school science teacher that absorbed photons would in fact impart less momentum than reflected ones. So his explanation couldn't work. Turns out I was right all along. Vindication feels good. :p

[savuporo]

Electrostatic charge on lunar surface as energy source is not entirely loony. See discussion here

https://space.stackexchange.com/questions/1725/would-it-be-practical-to-use-the-electrical-charge-of-the-lunar-surface-as-an-en

[john smith 19]

I vividly remember a heated debate between me and my high school science teacher that absorbed photons would in fact impart less momentum than reflected ones. So his explanation couldn't work. Turns out I was right all along. Vindication feels good. :p

It's deceptively simple. Obvious explanation "It heats the air inside," but it's got a partial vacuum. And you can make ones with both vanes black, if they are curved, and so on.

Quite tricky.

[stefan r]

Solar sails do not use the solar wind for propulsion - this is a common misconception.

There is this thing:
https://en.wikipedia.org/wiki/Electric_sail
And this:
https://en.wikipedia.org/wiki/Magnetic_sail

I get the impression you're just making up ideas. This site has a low tolerance for nonsense.

>Could use use antennas kilometers long and hundreds of meters high as nets or grids, to extract energy from the solar wind?<

That is complete nonsense. Please consider thinking before posting.

The patent office took similar nonsense seriously enough to award a patent:

https://www.google.com/patents/US4923151

...For example, tethers of 200 km producing 200 amperes, for a power generation capability of 8 megawatts, or tethers as long as 500 km that may produce up to 20 megawatts are reasonable...

That is designed for use inside earth's magnetic field. 

This one is designed for interstellar space:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050215611.pdf  It is in the NASA archives.  They are claiming 0.6 megawatts off of a 270 kg tether.