Natural photosynthesis is considered a good target for solar energy conversion, but it's already considered old hat. Harvard scientists have developed a leaf-like system that should be more effective at converting solar energy than plants themselves. The technology boils down to a jar of bacteria (Ralstonia eutropha), a cobalt water-splitting system and a pair of electrodes. When you send electricity through this partly biological system, the electrodes turn the water into hydrogen gas that you can use for fuel and carbon-based materials. It's only 10 percent efficient, but that's better than the widely established 8 percent baseline for real-world performance.