alo3
hydrogen would make a great fuel. the problem of course is storing it safely. as a gas it's not very dense. if you fill your trunk with hydrogen you can drive about as far as you can on half a tank of gasoline. kinda sucky. liquid hydrocarbons contain lots of easily releasable hydrogen in liquid form. unfortunately that doesn't solve the fundamental problem. interestingly enough, water also holds lots of hydrogen in liquid form. and it's perfectly safe. the problem of course is how to release it. one wacky proposal is to burn a metal like aluminum or sodium using water as the oxidizer. you end up with aluminum oxide and hydrogen. and heat. feed the hydrogen into your engine. mix it with air. and off you go. no emissions other than steam. you end up with rusty fuel pellets in your tank. which you exchange at the fuel station for fresh ones. in theory the spent ones can be recycled. neato. it still weighs twice as much as gasoline. but it's a lot smaller than compressed hydrogen gas tanks.