richasco, are you sure you arent talking about ethanol? I know propane can be done, but I thought the losses were greater than that. Could be wrong though.
bjoe, yes its true, any internal combustion engine can be converted to run on hydrogen. currently, if you convert (bigger PITA than its worth) you lose what feels like about 20% (I have come to understand), not due to the available energy (obvoiusly, hydrogen has more) but due to the fact that a cenverted engine does not burn hydrogen efficiently. With more research and an engine built from the ground up, it is possible (theoretically) to make a more powerful engine based on a piston-type engine. Most hydrogen used today is done in fuel call form where the hydrogen is converted into electric energy. I think this is done because of a more efficient transfer of energy from chemical the mechanical energy.
The requirements to switch to hydrogen are substantial. First, you ahve to find it. Not an easy task. Second, you have to store it in vehicle. Hydrogen must be pressurized and cooled to keep it in liquid form. Good luck with that part. And third, you have to get it from fuel tank to engine, without lowering pressure or raising temp. I am sure there are other obstacles I am overlooking too.
I find it easier to switch to ethanol. Lose maybe 10% mileage. Maybe have to get higher quality rubber hose, although if you have a post ~91 of any vehicle, it should be ok. You also have to get a computer that will adjust for it. <-- these can prove tricky to find, I ahve been looking and cant seem to locate one. Also, right now (at least in Denver) E85 (85% ethanol, 15% gas) is about $2 where gas is about $2.80, more than making up for the mileage difference.
All in all, cool idea and I hope he has some interesting findings, but I think he will find it to not be very feasable, unless he has outside sources of funding and it becomes more of a research vehicle. Tell him good luck.
