One two questions, how save is hydrogen in a car accident, and two what happens when millions of people start pouring water into their gas tanks. My concern is that a lot of people have access to clean water yet will be wasting is as a fuel when its other uses are most more important.
Japan is very innovative in R & D. They are pushing for advances in developing a engine that will be free of motor fuel.
I honestly don't see us using up all the water on this planet. However, if this does ever become mainstream the clip says that even ocean salt water can be used. The ocean levels are rising, maybe this can slow the rising ocean levels. That was my first thought too. If you find out, let me know.