Because hydrogen fuel gives off water as a byproduct and does not emit any carbon dioxide, many people believe it could one day compete with oil as the major transportation fuel. In Hydrogen Fuels, readers will discover how this simple element can create clean energy, how it is used in the present for space shuttles and fuel cells, and how it may be used in the future. Because hydrogen fuel gives off water as a byproduct and does not emit any carbon dioxide, many people believe it could one day compete with oil as the major transportation fuel. In Hydrogen Fuel, readers will discover how this simple element can create clean energy, how it is used in the present for space shuttles and fuel cells, and how it may be used in the future.