About carbon as a by product of Hydrogen. That is not always true. The reason they say it is a by product is because to get the hydrogen it requires an immense amount of energy and most power plants still use coal or some sort of fossil fuel. It we used nuclear power that would not be the problem. Although I wonder what will happen when we run out of Nuclear energy. I am just guessing on the Nuclear energy running out. I really don't know how the uranium and plutonium are created. The quest for power may never be over.