I heard that water could be used to manufacture hydrogen.
So let me get this straight. You can derive the hydrogen from water, then it also makes water as the waste product? So couldn't you collect that water and maybe even have something built into the car that converts the waste water back to hydrogen?
I am no physicist so I don't know if this is possible or not. Maybe in the near term you could just collect the water exhaust if it can't be converted back to hydrogen onboard.