Page 312 - Biofuels Refining and Performance
P. 312

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.
   307   308   309   310   311   312   313   314   315   316   317