Stationary Fuel Cells
Fuel cells essentially have three parts: the anode, the electrolyte, and the cathode. The electrolyte is a substance capable of conducting electrical current.
Fuel cells are typically characterized by the type of electrolyte they employ. The most well-known, shown above, are proton exchange membrane fuel cells (PEMFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC).
Various fuel cell technologies operate efficiently at different temperatures, which affects their suitability to provide electrical power for different applications. PEM fuel cells, for example, operate at relatively low temperatures, and this makes them suitable for automotive applications. A solid oxide fuel cell, on the other hand, can take up to eight hours to "warm up" and fully come on line ― an attribute that would be unacceptable to today’s drivers.
The electrical efficiency of fuel cells refers to the ratio of electrical energy produced by a system compared to the energy supplied.
Total efficiency refers to the ratio of electrical and thermal
energy produced by a fuel cell system compared to the energy
supplied. This number reflects the efficiency
when combined cooling, heat and power (CCHP) applications are part of the fuel cell system.
How a Fuel Cell Works
National Fuel Cell Research Center:
|Fuel Cell Technology||Electrolyte||Operating Temperature||Electrical Efficiency||Total
|Solid Oxide||Solid Metal Oxide||~1000◦ C||45 to 50%||70 to 80%||Primary Power|
|Solid Oxide||Solid Metal Oxide||~700◦ C||45 to 50%||65 to 75%||Primary Power|
|Carbonate||Molten Alkali Carbonates||~650◦ C||45 to 55%||70 to 80%||Primary Power|
|Phosphoric Acid||Phosphoric Acid||~ 200◦ C||35 to 40%||70 to 80%||Primary Power|
|Proton Exchange Membrane||Ion Exchange Membrane||~ 150◦ C||35 to 40%||55 to 65%||Backup Power
|Proton Exchange Membrane||Ion Exchange Membrane||~ 50◦C||30 to 35%||50 to 60%||Backup Power