One of the most promising and exciting distributed generation (DG) options is fuel cell technology, which converts fuel to electricity at high efficiency, without combustion, and with negligible emissions. Several different fuel cell technologies are under development and commercialization for various stationary and vehicular applications.

The Science
Fuel cells produce energy without combustion by an electrochemical process using hydrogen fuel. A fuel cell consists of two electrodes sandwiched around an electrolyte.  Hydrogen is fed to one of the electrodes. Oxygen (from the air) enters the fuel cell through the other. Encouraged by a catalyst, the hydrogen atom splits into a proton and an electron.  The proton passes through the electrolyte. The electrons create a separate current that can be utilized before they are reunited with the hydrogen and oxygen to form water molecules.
Fuel cells are a family of technologies.  Fuel cell types are characterized by their electrolytes and temperature of operation.
Fuel cells are the ideal solution when space is limited or weight is a concern, offering clean and quiet operation in a wide range of installation conditions. For example, the reduced footprint meets requirements for normal rooftop loading limits, and zero-emissions combined with quiet operation make fuel cells highly suitable for indoor, outdoor, urban or rural applications.