Hydrogen is most effective as a fuel when used in a fuel cell vehicle. Fuel Cells use hydrogen as fuel to generate electricity through an electrochemical process. The reaction starts when hydrogen is fed to the anode where a catalyst separates hydrogen's negatively charged electrons from positively charged ions (protons). The flow of electrons is used to supply an electrical load with current. Oxygen is fed to the cathode, where recombining of hydrogen with oxygen complete the reaction. The only byproducts from the process are heat and water; there is no pollution. With no internal moving parts, fuel cells operate similar to batteries. An important difference is that batteries store energy, while fuel cells can produce electricity continuously as long as fuel – hydrogen – and air are supplied.

Fuel Cell Animation

www1.eere.energy.gov/hydrogenandfuelcells/fuelcell_animation.html