The type of electrolyte determines the kind of chemical reaction, the kind of catalyst needed, the temperature range, and the type of fuel. All of these characteristics affect the applications the cells are most suitable for.
Low Temperature Fuel Cells |
High Temperature Fuel Cells |
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DMFC Direct Methanol Fuel Cell |
PEMFC Proton Exchange |
AFC Alkaline Fuel Cell |
PAFC Phosphoric Acid Fuel Cell |
MCFC Molten Carbon Fuel |
SOFC Solid Oxide Fuel Cell |
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| Electrolyte | Proton-conducting membrane | Proton-conducting membrane | Caustic potash solution | Concentrated phosphoric acid | Molten carbonate | Ceramic |
| Temperature Range | < 100°C | < 100°C | < 100°C | ~ 200°C | ~ 650°C | 800-1,000°C |
| Fuel | Methanol | Hydrogen | Hydrogen | Hydrogen | Natural gas, coal | Natural gas, coal |
| Power Range | Watts/kilowatts | Watts/kilowatts | Watts/kilowatts | Kilowatts | Kilowatts/megawatts | Kilowatts/megawatts |
| Application Examples | Vehicles, small appliances | Vehicles, small generators, domestic supply, block-type heat, power stations | Outer space | Block type heat, power stations | Power plants, combined heat and power | Power plants, combined heat and power |
Proton Exchange Membrane Fuel Cell (PEM)
In Canada, most fuel cell development focuses on Proton Exchange Membrane (PEM) or Polymer Electrolyte (PEFC) fuel cells. PEMs produce high-power density and are lighter and smaller than other fuel cells. In a PEM fuel cell, pure hydrogen fuel is combined with oxygen from air to produce electrical energy. The conversion process is environmentally safe – only heat and water are emitted as by-products.
PEM fuel cells use a solid polymer, which looks like kitchen plastic wrap, as an electrolyte and porous carbon electrodes containing a platinum catalyst. The electrolyte layer acts as a one-way door, allowing either positive or negative ions to travel across, but not electrons. This forces electrons to travel through the external circuit as electric current. Since they operate at low temperatures (approximate 80 degrees Celsius), PEM fuel cells are best for devices that require quick start-ups, such as vehicles, back-up power, and electronic devices.