Sorry, I though you were referring to hydrogen fuel cell batteries, not fusion. Those new fuel cell cars are totally pointless though, don't you agree? The greens push them even though you end up burning even more energy to produce the hydrogen. :crazy Another thing about hydrogen fusion is how the power comes to be. Now we all know that everything can be described as one of 3 things  1.solids(where particles are next to each other and can only vibrate a bit)  2.liqiuds(where particles are free flowing)  3.gasses(where particles are moving really really fast and bumping in to each other)  Now there is a fourth which cannot be found on earth and that is called 4.PLASMA where particles are moving so incredably fast that when they bump into each other they fuse and realise vast amounts of energy hence the name nuclear fusion  This is (in theory) the second most effective way to harness the power of an atom. The most effective way is point zero energy (this is what might make warp possible) If you would like me to explain about point zero energy and how it might be used to travel vast distances in space (or destroy planets) just ask in a reply, or you can tell me to shut up about the science s**t :)