Sun, but with a whole new solar collector that can just be stuck to your window and is see-through: http://www.ted.com/talks/justin_hall_tip...

I love this one, I am so hoping they work out the kinks and it will become available ASAP.

Possibly finding a way to harness the kinetic energy of a quark moving near or faster than the speed of light, although you would also need some way of turning them into a physical object since they are mass-less.

Try B12 its a natural vitamin for energy

Hemp