Environmental Engineering Reference
In-Depth Information
air for an oxidation reaction. This allows the molecules to split and ionize
while releasing or accepting protons and electrons.
On the hydrogen side of the membrane, a hydrogen molecule with
two hydrogen atoms will attach itself to two adjacent catalyst sites. This
frees positive hydrogen ions (protons) to travel across the membrane.
The reaction on the oxygen side occurs when a hydrogen ion and an
electron combine with oxygen to produce water. If this is not controlled
properly, highly corrosive by-products such as hydrogen peroxide can re-
sult, which quickly damage the internal components.
In a proton exchange membrane (PEM) fuel cell, protons travel
through a film 18 microns thick which is the proton exchange membrane.
Electrons are blocked by the film and take another path which provides
the electric current flow. Over time and usage tiny holes can form on the
film which reduces fuel cell performance. If the film is made thicker and
stronger, then performance suffers.
FUEL CELL BUSES
Ballard Power Systems supplied one of the first fuel cell demonstra-
tion projects for British Columbia Transit. Ballard is a pioneer and major
producer of fuel cells which it installed in several Vancouver, Canada city
buses. The fuel cell powered New Flier buses are much cleaner than new
diesels and they are not adding to Vancouver's smog problem. A similar
demonstration has taken place in Chicago, where the modified city buses
have been called the Green Machines.
The Vancouver pilot program was the world's first real test of fuel
cell vehicles. The buses are quiet except for the whirl of their air compres-
sors and have a range of 250 miles.
Ballard does not build cars, trucks, or buses. Its sole product is the fuel
cell in all of its many applications, plus the auxiliary equipment to make
them work. Since Ballard is a pioneer in modern fuel cells its technology
is advanced and its fuel cell sales have made it one of the fastest-grow-
ing automotive suppliers in the world with alliance partners including
DaimlerChrysler, Ford, Honda, Nissan, Mazda, Volvo, and Volkswagen.
The company started in 1979 building rechargeable lithium batteries
for smoke detectors. Geoffrey Ballard had worked for the U.S. Department
of energy. In 1983, he was approached by the Canadian Department of
Defense who were interested in fuel cells. Since they were similar in op-
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