Of all the commercial power-production...

methods, hydro-electric is probably the best all around choice, and that includes ecological impact (a very complex analysis is involved on that specific issue). It's main limitation: there's only so much flowing water!

The STIRLING solar gadget is cute, especially for driving air-conditioning units in hot, sunny places. If it's commercially viable (which I sincerely doubt, due to high front-end [capital] cost), you'll see lots of them. If it's not, you won't.

Astropower made solar-electric panels for commercial/residential installations. They went belly-up, and GE bought what was left. Basic problem: capital cost to make an average single home energy-independent was $30,000 about 5 years ago. With recent real-estate inflation, that's probably $60,000 today. Would you want to pay that UP FRONT or pay the utilities on a monthly basis, remembering also that all such systems require maintenance and eventual replacement (i.e. more costs).

"Money makes the world go around, the world go around, the world go around..."

Darwin certainly had most of it right: Survival of the fittest, adapt or die, etc. If it's commercially viable you'll see a lot of it, if it isn't, you won't.

Dave