Fuel alcohol and methane are good, but you cant count on being able to find them any where other than your house. hydrogen you can get from water at any gas station hose. the other problem with fuel alcohol, at least in USA is the feds. I have heard of people that got the license to make and sell alcohol in order to make fuel alcohol. because they are making fuel alcohol instead of alcohol for human consumption, they are required to denature their alcohol so that you cant drink it. then, even though it cant be drunk, they had to pay the alcohol tax incase it was ever drunk!!!