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Fuel Cells 291
then be used as the fuel for the fuel cell stack. The stored hydrogen
can also be used to fuel the fuel cell vehicles and so forth. In a grid-
connected wind/solar energy–hydrogen system, wind/solar power
whenever available provides electricity for hydrogen production. The
grid power is used during off-peak periods for low-cost electricity and
hydrogen production; whereas during peak-demand periods or no/low
wind/solar energy periods, the fuel cell can generate electricity using the
stored hydrogen. These hybrid systems could be configured in several
ways.
9.6 Conclusion
Fuel cell systems are one of the most promising technologies to meet our
future power generation requirements. Fuel cell systems provide a very
clean and efficient technology for electrical and automotive power sys-
tems. With cogeneration efficiencies higher than 80%, fuel cells prom-
ise to reduce primary energy use and environmental impact. Fuel cells
are a very good alternative for rural energy needs, especially in remote
places where there are no existing power grids or power supply is unre-
liable. The application of fuel cells into the transportation sector will
reduce greenhouse emissions considerably; if fuels from renewable
energy sources are used, it would nearly eliminate greenhouse gas emis-
sions. Utility companies are beginning to locate small, energy-saving
power generators closer to loads to overcome right of way problems and
transmission line costs. The modular design of fuel cells suits this dis-
tributed generation strategy very nicely as new modular units can be
added when the demand increases. This reduces the financial risk for
utility planners. Biofuel cells are very attractive for implant devices as
they can use glucose in blood to power these devices, eliminating the
need for surgery for maintenance and battery replacement. Use of
digester gas as a fuel in biofuel cells makes them very attractive for
power generation from garbage and other organic waste. This will also help
in waste disposal, a big problem in the agriculture and food industry.
All fuel cell technologies (PEMFC, DMFC, AFC, PAFC, MCFC, SOFC,
and MFC) discussed in this chapter are in a very advanced stage of
development and are very near to commercialization. Although a
number of demonstration units of different types of fuel cells are oper-
ating all over the world and many PAFC and AFC units have been com-
mercially sold and are successfully operating, fuel cells are still awaiting
widespread commercialization due to their high cost and limitation in
the choice of the fuel used. These barriers will be overcome in the next
few years, and fuel cells will become a preferred power source with
widespread applications.