I posted previously about a future energy source: solar panels in space. Without an atmosphere to get in the way, and without that whole "day and night" thing, solar panels can absorb easily 300% of the energy they would on Earth. Because the energy would be constant, we could avoid having to build wasteful methods of preserving energy for night or cloudy days. Overall, its a very promising technology.
But there are downsides: specifically, cost. Shooting things into space is not cheap. The best figure I could find puts bringing a US ton of matter into space at just under $10m. That would decline if we sent more things into space: it's far more expensive to build individual shuttles then to mass produce the launching mechanisms. But even at a quarter the cost, the economics of these space panels is questionable. You might not get as much sunlight on Earth, but space travel is a pricey proposition. Thus while these space panels may someday form a viable energy source, we're probably not ready yet.
But there's a better option, I've realized. Space solar panels work so well because of the lack of an atmosphere: well, the moon lacks one as well. Solar panels are usually constructed of silicon, which turns out to be the second most prevalent element in the moon's crust. Instead of building solar panels here on Earth and tossing them out of our gravity well, we could just construct the solar panels on the moon. This turns it from a question of cheap space travel to a question of extraterrestrial construction. Any complicated machinery would be constructed here on Earth, then rocketed to the moon. There, cousins of the Mars Rover would shovel moon dust into little self contained factories. Solar Panels would come out, be laid in grids across the lunar surface, and hooked up to a microwave generator that would beam plentiful energy back to Earth. We'd have to keep sending new robots and factories as they break (at least in the short term), but besides that the solar panel fields could grow and grow and grow. Plentiful energy for all!
And it would, I suspect, have to be for all. Space is one thing, but moon-based construction is going to be a thorny political issue. Who owns the land on the moon? The first person to start using it? And would it be rational for America (if we're the ones building the Lunar Solar Fields) to switch to a pure solar energy society while China continues burning coal? No, I suspect it makes far more sense to get everybody over to to this climate friendly energy source as soon as possible. It would require an unprecedented degree of global cooperation, which worries me. But if we could find an agreeable way to distribute the energy we could move over to a vastly more environmentally friendly energy source in the very near future. It's a tricky engineering problem: constructing factories in an inhospitable environment with minimal direct human interaction, but its not something that strikes me as beyond our current means. It shouldn't require terribly advanced robotics, or major advances in solar panel construction. Someday you may look up at the moon and see a little splotch of black, and in the following decades that black would grow until our great grandchildren look up at the sky and can dimly make out a great spherical solar panel, orbiting the planet, providing energy more plentiful then anything we've ever known.