Alternative Drive Systems – Generation B
PEM fuel cells: power from hydrogen
Fuel cell stacks convert energy from one form into another. They change the chemical energy in hydrogen — the primary energy source — into an electrical current, and they do this very effectively, with an efficiency of around 80 percent. Mercedes-Benz F-Cell vehicles are fitted with stacks featuring so-called PEM (proton exchange membrane) fuel cells. Such fuel cells run on pure hydrogen and have decisive advantages for mobile applications.
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For example, they operate at a relatively low temperature of around 80 degrees Celsius, which makes them suitable for vehicle drive systems.
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In addition to the hydrogen fuel, only air is required as an oxidant.
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PEM fuel cells respond immediately to an increased or decreased influx of fuel, which is controlled by the pressure on the gas pedal,
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and the only emission they produce is pure water vapor.
There is no need to rate the fuel cell system for the maximum power requirements of the electric motor. If the latter suddenly requires lots of energy for sharp acceleration, a traction battery comes on line to aid the fuel cell. The B-Class F-Cell, for example, is equipped with powerful lithium-ion storage batteries.
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