Since solar-energy has been brought up, there was an interesting article on Slashdot yesterday about concentrated solar collectors. They're positively genius. Instead of trying to convert the photons into electricity, they collect and store the heat, which then runs steam-driven turbines.
They are simple and efficient, and they've been in operation since the 70's.
Here's a link to the slashdot comments
http://science.slashdot.org/article..../04/15/1159257
which contains a link to the original article.