We all know solar power generation is limited by how much sunlight energy reaches the earth. Our atmosphere and distance from the sun limits this (not to mention each location on earth only has a few hours of strong sunlight each day). Why not construct a solar energy generation station in space and send the energy back to earth? There are two ways to make storable energy from sunlight (quickly): photovoltaic cells and concentrating sunlight on earth to heat liquids. Both methods can either generate electricity directly or be used to split water into hydrogen and oxygen (storing the energy for either burning or powering a fuel cell to create electricity). A photovoltaic generation station would be stationary, generating hydrogen, and rockets would arrive empty from earth (powered by hydrogen based fuel) and be filled then return to earth mostly by earth's gravitational pull. A heat based station would need to pass close to the sun and then into cooler regions of space to allow the liquid to change states from liquid to gas and in the process generate power to split hydrogen, and again the hydrogen would be shipped back to earth by rockets fueled by the very fuel they ship. One problem is that water is very heavy and it would take a lot of energy to transport water to either station from the earth. Could we gather water from asteroids and other ice bearing bodies? What would be the cosequence of bringing back excess water from space to the earth? Would we be polluting the earth with water? We would probably have to bring back both the oxygen and hydrogen, otherwise if we only bring back the hydrogen (the more useful gas) it would rejoin with earth's oxygen and deplete overall oxygen levels (not good for oxygen utilizing animals like man). Thoughts? Suggestions? Engineers, Scientists?
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The best space launch systems can only orbit a payload that is a small fraction of the weight of the fuel they use. Obviously, it would do no good to use 100 tons of fuel to retrieve 10 tons of fuel.
Other people have suggested other ways of getting energy down to Earth without using ships. One way is to use a high powered laser. The solar satellite could collect energy and then periodically beam it to a collector on the Earth when it passes over it. Or it could be put in geostationary orbit and beam energy down continuously. However, the laser technology isn't really ready yet either. There are also safety concerns about the beam, as it would be a potential death-ray.
Right now, ground-based solar collectors are the best option, even if they only work for a few hours per day.
Moving matter to and from space is both very dangerous and horribly expensive. It has been proposed to build space stations or satellites to concentrate radiant energy and broadcast it to stations on Earth which would transform it into electricity but the investment is huge and a concentrated beam to Earth could cause terrible disasters if not held exactly to the receiving station. If a space elevator ever becomes possible it might connect a receiver of energy at the space end to transmit it down a cable to Earth but stability here would probably be a problem too.
I hate it that when new people suggest ideas, we just disagree. Keep trying, Hargrove2.
I'm with Dwane and sand. Hydrogen does weigh something, so you're going to spend fuel to de-orbit it and you'll need fuel to get a new container back to your station to refill. And to get water from asteriods, you'll spend more fuel-probably more than if you brought the water from home.
I'm in favor of exploring the energy-space-station concept, but not as a hydrogen producer--there's just not enough energy there to make it worthwhile to transport. You say 'there are two ways to make storable energy from sunlight' but I think there are many--flywheels, compressed gas, chemical reaction other than H2O, etc. Or don't store it--beam it home. Not a new idea here, Asimov was writing of it in 1941. Great story:
http://en.wikipedia.org/wiki/Reason_(Asimov)
Also, nuclear could conceiveably be generated in space and then transmitted to earth.
As for solar, it's just way-cheaper to make collectors on earth and the amount of sunlight that hits the whole earth in one second would power all of our cities for months. Maybe a big steered mirror in space to double the sunlight for the earth-bound collectors? That might 'concentrate' the energy a little, but not enough to harm if steered badly.
The only practical way to do this is developing a solar powered satellite (SPS) in high earth orbit and converting energy to microwaves which is beamed back to earth and collected by rectenna. Although the technology exists (small scale on earth), it would be hugely expensive just to send up a small prototype into orbit. See www.economicexpert.com/a/Solar:power:satellite.htm
Thanks for the replies, and great ideas and input. I Googled the microwave beam idea and it turns out there are prototypes being proposed (see: http://abcnews.go.com/Technology/Story?id=98547&page=1 ). Good to hear some entities are looking into this and other alternatives. It'd be nice if we could lassoo some other heavenly body, an asteroid, meteor or something, that had sufficient quantities of metals and other useful raw materials into an earth orbit so we could build some of the infrastructure in space instead of having to boost it out of earth's gravitational hold. Any ideas about what we could mine from the moon as far as materials go?