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The Future of Fuel Cells
A
meter-reader diligently checks the meters in a
neighborhood. When she examines one residence,
she discovers the home has not used any electric-
ity; in fact, the home has produced excess electric-
ity. She takes a second look, makes a note (some-
thing she is beginning to make more frequently), and moves on.
Over the fence, next to the pool heater, a refrigerator-sized fuel cell
quietly hums at 60 decibels. The fuel cell provides power for the entire
home, and the heat generated by the process is captured to heat the pool
and the Jacuzzi. The owners installed their own personal low-emission
power plant, which works 24/7, sending the excess energy that it pro-
duces back to the “grid.” Once used primarily by NASA programmers, the
fuel cell is now a consumer option for automobiles,
back-up power generators,
and primary heat and
Practical
Power
by Matthew Kustura
power systems for residential and commercial buildings.
Invented more than 170 years ago, fuel cells utilize the hydrogen in
natural gas and oxygen from the air to electrochemically produce elec-
tricity and heat. The U.S. Department of Energy claims, “Fuel cells have
the potential to replace the internal combustion engine in vehicles and
to provide power in stationary and portable power applications because
they are energy-efficient, clean, and fuel-flexible.”
How A Fuel Cell Works
Natural gas fuel cells consist of three systems: first, a fuel processor
separates hydrogen from natural gas in a catalyst bed; second, a fuel stack
(often consisting of hundreds of “cells”) takes in the hydrogen and sends hy-
drogen electrons out as Direct Current (“DC”) power. Oxygen then combines
with the hydrogen protons and carbon from the natural gas to produce water
and carbon dioxide. A third inverter system converts the DC power into 120-
volt alternate current (“AC”) power. The heat produced during this process
is captured using heat exchangers to provide heat for pools, domestic hot
water, central or radiant-floor space heating, and other thermal loads.
Efficiency and Emissions
Fuel cells generate power more efficiently than burning fossil fuels,
meaning fuel cells release more of the energy stored in the fuel source. A
search for an efficiency rate consensus yielded various estimates. Some
sources claimed that with combined heat and power systems (CHP),
efficiency is roughly 60%, while other sources claimed 90%. Neverthe-
less, energy produced at a coal power plant, according to a report by the
National Energy Technology Laboratory, was 32% efficient in the United
States in 2007. Natural gas power plants, which provide the major-
ity of power and heat in California, can produce power at slightly over
50% efficiency, while releasing 43% fewer carbon emissions than coal
and 30% less than oil, but the combustion of natural gas still releases
nitrogen oxide, a cause of smog and acid rain. Furthermore, transmis-
sion losses, which occur as power is distributed from the grid, result in
another drop in overall efficiency levels.
Since fuel cells do not combust fossil fuels, emissions of sulfur dioxide
The fuel cell
generates constant
heat and power
without combustion
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