And now the space-based solar power crowd has returned. These “experts” point to the increase in efficiency that could be achieved by putting solar collectors in Earth’s orbit and beaming the energy down to the ground.Spencer is assuming a lot here. He's assuming launch costs will remain high, solar technology will be slow to improve, and that global energy demand won't bring across-the-board energy price increases that make previously uncompetitive technologies competitive.
And indeed you probably could get several times the amount of energy from a solar collector in space versus on the ground. Too bad it would be insanely expensive.
You might have heard of the problems NASA has had with relatively tiny solar collectors attached to the Space Station and Space Telescope. Now imagine putting a one-square mile collector in space. Even if we could get such a thing designed, built, launched, and working, it would replace only 1 of the 1,000 one-gigawatt plants I mentioned earlier that the U.S. alone needs.
Nobody knows today whether space solar power (which could involve arrays on the moon as well as in Earth orbit) will be economically viable decades from now. The best way to find out is to let the full range of non-carbon energy sources compete in as free a market as possible.