California Stationary Fuel Cell Collaborative

Fuel cell technologies

Fuel Cell Technology1

Electrolyte2

Operating Temperature3

Electrical Efficiency4

Total Efficiency5

Application6

Alkaline

Potassium Hydroxide

~ 80◦ C

40 to 45%

60 to 70%

Primary power

Molten Carbonate

Molten Alkali Carbonates

~650◦ C

45 to 55%

75 to 80%

Primary power

Phosphoric Acid

Phosphoric Acid

~ 200◦ C

36 to 38%

75 to 80%

Primary power

Proton Exchange Membrane

Ion Exchange Membrane

~ 50◦ C

30 to 35%

50 to 60%

Backup power,
transportation,
primary power

Solid Oxide

Solid Metal Oxide

~1000◦ C
~650◦ C

45 to 50%

75 to 80%
60 to 70%

Primary  power

The table above shows a second way to categorize fuel cells ― by technology.

1 There are a number of stationary fuel cell types, and they are typically characterized by the type of electrolyte they employ.  The most well-known, shown above, are alkaline fuel cells (AFC), molten carbonate fuel cells (MCFC), phosphoric acid fuel cells (PAFC), proton exchange membrane fuel cells (PEMFC), and solid oxide fuel cells (SOFC).

2 Fuel cells essentially have three parts:  the anode, the electrolyte, and the cathode.  The electrolyte is a substance capable of conducting electrical current.

Fuel Cell Graphic by technology

3 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.

4 Electrical efficiency refers to the ratio of electrical energy produced by a system (such as a fuel cell) compared to the energy supplied (usually chemical energy).

5 Total efficiency refers to the ratio of electrical and thermal energy produced by a system (such as a fuel cell) compared to the energy supplied (usually chemical energy).

6 Visit markets and applications to see how your organization might best employ these technologies.

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Last updated on September 27, 2007 2:04 PM ©2007 California Stationary Fuel Cell Collaborative
   This site maintained by the National Fuel Cell Research Center