Fuel cells - Fs green Technology 01 02

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Fs green Technology 01 02Bog'liq 34. FS-Green-TechnologyFuel cells
Fuel cells convert the chemical energy contained in hydrogen to electricity and heat using an electrochemical
process. Inside a fuel cell, hydrogen electrochemically merges with oxygen to create electricity, resulting in
water and potentially useful heat as by-products. There are many types of fuel cells, though in general, they all
share the same basic configuration, featuring two electrodes sandwiched around an electrolyte. The types of
fuel cells are categorized by the electrolyte substance.
Power produced by a fuel cell depends on the fuel cell type, size, operating temperature and the gas supplied.
Hydrogen is the most optimal fuel for use in fuel cells. However, other hydrogen-rich fuel sources, such as biogas
from waste treatment and natural gas, which are rich in methane, can also be used as fuel. Fuel cells can be
used for backup power, power for remote locations, distributed power generation and combined heat and
power applications. To sustain electricity generation, though, the fuel needs to be supplied continuously; thus a
reliable supply of gas or a bulk storage system is needed.
Because fuel cells do not use combustion, emissions are much lower, and conversion efficiency is higher than
with conventional thermal power generation. A typical conventional combustion-based power plant has
around 33–35 per cent efficiency, while fuel cell systems can generate electricity at efficiencies up to 60 per
cent.
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Unfortunately, fuel cell technology has not advanced to the point where it can compete with conventional
power generation. The two main barriers to the commercializing of fuel cells are cost and durability. Material and
manufacturing costs for fuel cells are high compared to traditional combustion systems, and fuel cells have not
demonstrated the needed system reliability and durability to compete with existing technologies.
Energy storage
Energy can be used more efficiently through the addition of short- and long-term energy storage, both on and
off the grid. Thermal and electrical energy storage systems enable more efficient power generation by balanc-
ing fluctuating energy supply and demand. Thermal energy storage can also be used to reduce electricity con-
sumption by increasing the efficiency of heating and cooling systems, while an electrical storage system can
supply excess electricity, which is generated during periods of low consumption, to meet peak power demand.
Depending on the technology, energy can be stored as electrical, chemical, thermal or mechanical energy.
Not all technologies are suitable for every application, however, mainly due to power output and storage
capacity limitations. Identifying a suitable storage technology depends on several factors, such as storage
capacity, charging and discharging power, efficiency, storage period, storage cycle and cost.
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International Energy Agency, Technology Roadmap Geothermal Heat and Power (Paris, 2011). Available from
www.iea.org/papers/2011/Geothermal_Roadmap.pdf (accessed 10 January 2012).
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United States of America, Hydrogen & Our Energy Future (Washington, D.C., Department of Energy, 2009). Available from
http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/hydrogenenergyfuture_web.pdf (accessed 10 January 2012).
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