Easier than spinning gold from straw.

http://news.slashdot.org/story/12/10/19 ... edium=feed

That technology has been understood for years. It's basically a reversal of the oxidization process that goes on when hydrocarbons are "burned" Hxx Cx + O2 = Co2 + H20. Hydrocarbons and air basically turning into water and carbon dioxide The problem is reversing the process requires a lot of energy, more than what was extracted in the first place.

Dirt cheap clean energy is required to make the process economical. Taking it from a coal fired grid is not.