Considering that most of our world's covered in water, supply is hardly an issue. Desalination is a problem, but there are ways and means.

Hydrogen fuel cells have been in use since the early years of the space age... the moon landings, even, used cells as a power source. If we'd spent the last forty years developing this technology, it'd be practical, safe and widespread by now. However, thanks to the glory of petroleum, there was absolutely no financial incentive for development. Because of money, we're decades behind where we should be, facing fuel supply crises and other issues as a direct result. Our species are such winners sometimes.