We need to find a fuel to replace the oil which is running out.
Growing crops to produce oils or ethanol doesn't scale well enough.
Hydrogen works well in engines or in fuel cells but is a pain to store and transport.
Purely electric cars are great except for the batteries.
Well some smart people at Purdue University have stumbled across a chemical reaction which might allow a transport fuel cycle that goes like this:
- Generate electricity (from wind, solar, nuclear, whatever)
- Capture and concentrate most of this energy by using it to convert aluminium oxide into aluminium metal in an alloy with gallium
- Put pellets of the energy-containing alloy into a car's fuel tank
- Add water, which reacts with the alloy to produce hydrogen gas (with most of the energy in it) and aluminium oxide
- Use a fuel cell to convert the hydrogen back to water, with the energy extracted as electricity to power a motor
- Send the spent alloy back to the factory for "recharging"
But it's at least a possibility, and the more possibilities we have the better.