A fuel cell is an electrochemical device that converts the chemical energy from a fuel directly into electricity and heat.
When hydrogen is supplied as the fuel, it reacts with oxygen to produce electricity, and the only by-products are water and heat. This process is clean, silent, and incredibly efficient. A fuel cell can generate power as long as a fuel source is supplied, unlike a battery which is limited to the stored energy within. Fuels cells are capable of operating on a number of fuels, including natural gas, propane and hydrogen. In these cases, fuel cells do have carbon emissions, which contributes to global climate change, but at a rate significantly less than typical fossil fuel generators or electricity, and they still avoid considerable emissions of other pollutants as well.