Comparison of Fuel Cell Technologies
Fuel Cell Type
Common
Electrolyte
Operating Temperature
System Output
Efficiency
Applications
Advantages
Disadvantages
Polymer Electrolyte Membrane (PEM)*
Solid organic polymer poly-perfluorosulfonic acid
50 - 100°C
122 - 212°F
<1kW 250kW
50-60% electric
Back-up 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
Alkaline (AFC)
Aqueous solution of potassium hydroxide soaked in a matrix
90 - 100°C
194 - 212°F
10kW 100kW
60-70% electric
Military
Space
Cathode reaction faster in alkaline electrolyte so high performance
Expensive removal of CO2 from fuel and air streams required
Phosphoric Acid (PAFC)
Liquid phosphoric acid soaked in a matrix
150 - 200°C
302 - 392°F
50kW 1MW
(250kW module typical)
80 to 85% overall with combined heat and power (CHP
(36-42% electric)
Distributed generation
High efficiency
Increased tolerance to impurities in hydrogen
Suitable for CHP
Requires 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)
85% overall with CHP
(60% electric)
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 yttira is added
650 - 1000°C
1202 - 1832°F
5kW 3MW
85% overall with CHP
(60% electric)
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
High temperature enhances corrosion and breakdown of cell components
Slow start-up
http://www.eere.energy.gov/hydrogenandfuelcells/fuelcells/fc_types.html
pdf link at bottom of page
Kirk
Chip Mefford <[EMAIL PROTECTED]> wrote:
Kirk McLoren wrote:
> Fuel cells of 50% efficiency can be purchased now.
Really? Where?
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