Hydrogen is the simplest element. An atom of hydrogen consists of only one proton and one electron. It's also the most plentiful element in the universe. Despite its simplicity and abundance, it does not appear naturally as a gas on the earth, instead always in combination with other elements (for example, it is found in water).
Fuel cells are the same type of energy used in rocket engines. It is said that these will, in the future, become the main energy source for homes, businesses -- even vehicles. Fuel cells are high in energy yet they release few pollutants -- their main by-product is pure water.
Fuel cells are similar to batteries, in that they convert the energy from a chemical reaction, into useful electricity. The difference is, that Hydrogen Fuel Cells will produce electricity so long as fuel is supplied.
To function effectively, fuel cells need pure hydrogen. That said however, they can and do use hydrogen used from a process of reforming, that is, separating hydrogen from hydrocarbons (which make up most of our current fuels) by application of heat. Electrical currents can also be used to separate water into its components of oxygen and hydrogen, thereby giving the world plenty of available fuel to be used for energy.
More about fuel cells