BMW monofuel

BMW is showing off a 7 series designed solely to run on hydrogen. The cool part, it burns it in a real engine, just like gasoline, except without the nasty bits.

No word on the cost (although it is a 7 series, so that shouldn't be as huge an issue) but this thing actually might work. It has none of the problems of batteries; recharging, or fuel cells; you might be able to make the engines affordable before the end of time.

As to how you make the hydrogen, utility solar looks like a pretty good, and actually existing, start.