Fuel Cell Type |
Common Electrolyte |
Operating Temperature |
System Output |
Electrical Efficiency |
Applications |
Advantages |
Disadvantages |
Polymer Electrolyte Membrane (PEM) |
Solid organic polymer poly-perfluorosulfonic acid |
50 - 100°C
122 - 212°F |
<1kW – 250kW |
60% (direct)
25-40% (reformed) |
Backup power
Portable power
Small distributed generation
Transportation |
Solid electrolyte reduces corrosion & electrolyte management problems
Low temperature
Quick start-up |
Requires expensive catalysts
High sensitivity to fuel impurities
Low temperature waste heat
Waste heat temperature not suitable for combined heat and power (CHP) |
Direct Methanol
(DMFC) |
Solid organic polymer poly-perfluorosulfonic acid |
50 - 100°C
122 - 212°F |
Up to 1.5kW |
20 - 25% |
Consumer goods
Laptops
Mobile phones |
High energy storage
No reforming needed
Easy storage and transport |
Low power output
Methanol is toxic and flammable |
Alkaline (AFC) |
Aqueous solution of potassium hydroxide soaked in a matrix |
90 - 100°C
194 - 212°F |
10kW – 100kW |
60% |
Military
Space |
Cathode reaction faster in alkaline electrolyte, higher performance |
Expensive removal of CO2 from fuel and air streams required (CO2 degrades the electrolyte) |
Phosphoric Acid (PAFC) |
Liquid phosphoric acid soaked in a matrix |
150 - 200°C
302 - 392°F |
50kW – 1MW
(250kW module typical) |
32-38% |
Distributed generation |
Higher overall efficiency with CHP
Increased tolerance to impurities in hydrogen |
Requires expensive platinum catalysts
Low current and power
Large size/weight |
Molten Carbonate (MCFC) |
Liquid solution of lithium, sodium, and/or potassium carbonates soaked in a matrix |
600 - 700°C 1112 - 1292°F |
<1kW – 1MW
(250kW module typical) |
45-47% |
Electric utility
Large distributed generation |
High efficiency
Fuel flexibility
Can use a variety of catalysts
Suitable for CHP |
High temperature speeds corrosion and breakdown of cell components
Complex electrolyte management
Slow start-up |
Solid Oxide (SOFC) |
Solid zirconium oxide to which a small amount of Yttria is added |
650 - 1000°C
1202 - 1832°F |
5kW – 3MW |
35-43% |
Auxiliary power
Electric utility
Large distributed generation |
High efficiency
Fuel flexibility
Can use a variety of catalysts
Solid electrolyte reduces electrolyte management problems
Suitable for CHP
Hybrid/GT cycle |
High temperature enhances corrosion and breakdown of cell components
Slow start-up
Brittleness of ceramic electrolyte with thermal cycling |
Source Mostly US DOE Energy Efficiency and Renewable Energy (EERE) August 2007