HYDROGEN IS NOT A SOURCE OF ENERGY. It is only an inefficient way to make energy portable, and a very expensive one at that, It makes a great rocket fuel where cost is irrelevant, but is the cost of heating your house or running your car irrelevant? Liquid hydrogen has a density of only 0.07 % of water, that is why the Space Shuttle had such a huge external fuel tank. You could not fly a plane across the Atlantic with hydrogen fuel unless you give up all your cargo space for fuel. We could add it to the natural gas supplies that we use, but you would need even larger nozzles because its very low density means that you would need a larger volume of gas for a given amount of energy. To be specific, It has 33,817 cal/ g, about three times that of liquid fuels, but 1/10 the density. It needs a foot thick insulation to store it, and forget rubber hoses at -200C