Believe it or not, I was working on such a project my last semester in college. I looked into designing such a vehicle, which could just be pumped full of water. The problem with hydrogen fueled cars is that hydrogen is VERY explosive and such a solution to the problem of transportation of such a dangerous gas would be just what you said.. fuel cars off water, let them make it into hydrogen for their fuel cells.... problem is.. its not quite feasible. There are too many efficiency drains in the cycle. And the car would basically have to be a hybrid.. but with technological advances, it could happen someday... E... I think you are forgetting the probelm of "Nuclear Waste". The problem isnt that people are afraid of only nuclear meltdowns, they are also scared of where the waste would go and what we would do with it... our current solution of burying the waste scares too many people, and has caused too many problems.. people are afraid of becoming the perfect nuclear family... literally.. hahaha..