This crazy dude I used to work with (and I mean that in the nicest way possible) liked to point out that the theoretical specific energy of a battery (that is e

This crazy dude I used to work with (and I mean that in the nicest way possible) liked to point out that the theoretical specific energy of a battery (that is energy per unit mass) is c squared. By that standard it is entirely possible we might one day have cars that ship with all the fuel they'll ever need stored in a little capsule the size of a thimble. But it's one of those "in principle not impossible" kinds of technologies that are fun to think about but unwise to bet the future of the planet on. What would be really cool is if someone figured out a way to generate electricity from a nuclear reaction without going through a heat step—to somehow fling off electrons without moving the nuclei around much. In the mean time I suppose we could also shine this guy's laser at a solar cell like the article a few weeks back suggested.