[etlib]

Third, we must develop promising new sources of energy, such as hydrogen, ethanol or biodiesel.

Hydrogen is not an energy source. It's an energy storage and transmission medium. Hydrogen must be generated from water using some other energy source. When it is burned it produces water. This cycle must result in an overall loss of usable energy meaning that the use of hydrogen as a fuel may use up more of the energy source than other fuels.

Hydrogen is also less efficient to store and transport than gasoline. It may not even be much less polluting since much of the pollution created by gasoline is due to oxygen nitrogen reactions resulting from the use of air rather than pure oxygen.

The water -> hydrogen -> water cycle also means that more carbon dioxide will be produced in the first step of the cycle than if the original fuel was used directly.

[ARCADIA]

Hydrogen is not an energy source. It's an energy storage and transmission medium.

Every form of energy that we have ever used, from wood through nuclear fission, is just the harvesting of stored energy. The trick is to find a form of potential energy that can be efficiently produced and used in an application. Gasoline powered automobiles are good, electric/battery powered autos are less good, perhaps hydrogen powered autos will be better. All are driven by stored energy, it is just a question of using a power sources that has a sufficient energy to weight ratio.