Burned or used in fuel cells, hydrogen is an appealing option for powering future automobiles. This nontoxic gas could serve as a pollution-free energy carrier for machines of many kinds. When burned, it releases no carbon. Dioxide, a potent greenhouse gas. And if hydrogen is fed into a fuel cell stack and a battery device that generates electricity from hydrogen and oxygen that can propel an electric car or truck with only heat and water as by products. The fuel cell