After electricity, the form of energy we would miss most is that in gasoline. Our dependence on oil leads us into wars in the Middle East. The price of oil disrupts our economy. The oil crisis of 1973 was so severe that a speed limit of 55 miles per hour was legislated in the USA. (But it had the beneficial effect of increasing government funding for controlled fusion research!) Train buffs will remember the times when trains carried coal, and this was shoveled into steam engines to drive the huffing and puffing trains across the country. Nowadays liquid fuel is at a premium. Gasoline, diesel fuel, and liquefied natural gas are used for transport by cars, buses, trucks, trains, airplanes, and ships. Half of all the world’s oil is used for transportation. How can this be replaced by clean energy? Wind and solar produce electricity, which is not easy to carry around. We cannot all drive nuclear submarines.

Hydrogen has been hyped as a promising candidate for a nonpolluting fuel. It is surprising how many people still think that hydrogen is a source of energy! In fact, it takes a lot of energy to produce hydrogen. Water is one of the most stable elements on earth, which is why we have a blue planet. To take H2O apart into hydrogen and oxygen requires a large energy source to supply the world’s trans­portation needs. Cars run on hydrogen emit only water, but hydrogen is currently produced from natural gas. This not only depletes our precious reserves, but also carbon dioxide is emitted in the process. Even though we still use fossil energy to make hydrogen, transportable hydrogen still has a role to play in reducing pollu­tion. To clear up popular conceptions on hydrogen, we will consider this topic first.