Of all the outlandish clean-energy ideas out there, space-based solar power has always seemed like one of the most intriguing. The rough concept is that satellites would gather solar energy while floating in orbit (and, lucky them, they'd never need to worry about cloud cover or rain, so they could collect 25 times as much sun as a land-based system would). They'd then somehow beam the energy down to Earth—er, this step still has a few kinks to work out—where, finally, it would get converted back into electricity. Et, voila.
Theoretically, sure, it's possible. But practically, early prototypes will be outrageously expensive, and launching the satellites into space would require an enormous amount of energy to begin with. Still, for those hoping to keep the dream alive, check out Jennifer Kho's report at Earth2Tech on PowerSat Corp., a company that just filed a patent for two technologies it claims will make space solar more competitive by cutting the costs of launching the satellites.
For a dose of skepticism, meanwhile, read NYU physicist Marty Hoffert's note on how a very small space-based solar project might be doable over a medium-term time frame (which, in turn, could "realistically lead to a buildup of a viable orbital and power industry"), but that any such project would require huge amounts of federal investment, and probably couldn't be financed by private sources alone. Indeed, PowerSat estimates that a small, 2.5 gigawatt prototype would cost $4-$5 billion, and get running by 2019 at the earliest.
That means, in the near future, those old-fashioned, down-to-earth solar-thermal plants are still looking like the safer bet for providing sun-based energy. (Although, as The Wall Street Journal's Stephen Power reports today, federal land regulations are bogging down the solar-thermal boom in the U.S. Southwest, with a huge backlog of applications piling up at the Bureau of Land Management. So I guess that's one advantage space-based solar might have over its terrestrial counterparts...)