Los Alamos "Green Freedom" This is a fairly http://www.lanl.gov/news/index.php/fuseaction/home.story/story_id/12554" concept was interesting. Basically, you capture CO2 from the atmosphere, electrolyze water, and use the CO2 and H2 to synthesize whatever hydrocarbons you want. One of their specific designs is for methanol synthesis, so that could later be used in a http://en.wikipedia.org/wiki/Direct-methanol_fuel_cell" [Broken]. Obviously the overall process is endothermic so it requires energy input, but maybe this is a reasonable way to avoid grid fluctuation issues for wind and solar. When they are over-producing power they can generate valuable hydrocarbons instead of pushing unneeded electricity onto the grid. Not something for the next few years, but it could be useful later.