Environmental Engineering Reference
In-Depth Information
All fuel cells produce some by-product heat, but the temperature of by-product heat can vary
dramatically, from about 180°F for PEM fuels to more than 1,200° for molten carbonate fuel cells.
Fuel cells that produce high-temperature by-product heat with over 250 kilowatts of capacity are
suitable for combined heat and power generation applications in industrial and large commercial
settings. Those that produce low-temperature by-product heat are suitable for both mobile uses,
such as light-duty vehicles and forklifts, and residential applications providing electricity plus
space and water heating (USEIA 2008b).
The installed capital cost of phosphoric acid fuel cells in the commercial sector varies accord-
ing to size. For 200-kilowatt systems, the cost quoted by United Technologies Corporation for
the PureCell 200 ranged from $6,000 to $7,750 per kilowatt, and for the PureCell 400 system
the installed cost ranged from $3,625 to $4,500 per kilowatt in 2008. The first generation of
commercial molten carbonate fuel cells in 2010 cost about $6,200 per kilowatt. Molten car-
bonate fuel cells use high operating temperatures of the fuel cell to reform methane and steam
to produce hydrogen. The CO 2 produced is recycled to restore the chemical used to generate
electricity. Efficiencies for production of only electricity can approach 50 percent, and overall
efficiencies (electricity plus by-product heat) are about 70 percent when both products are fully
used (USEIA 2008b).
If research succeeds in lowering installed capital costs of molten carbonate fuel cells below
$2,500 per kilowatt, the technology could satisfy a significant percentage of new demand for
combined heat and power in industrial and commercial markets. The resulting market penetration,
once cost reductions are achieved, may be slow because industrial and commercial boilers are
long-lived and are rarely replaced before they fail. Consequently, fuel cell technology is unlikely
to replace existing boilers or existing cogeneration equipment before it fails. Market potential in
the commercial sector is better but does not promise rapid growth. Commercial electricity and
heat demands are expected to grow more quickly than in the industrial sector. Nevertheless, it
appears unlikely the capital costs and performance of molten carbonate fuel cells will improve to
levels needed for substantial penetration of this new market (USEIA 2008b).
With only about 1,350 hours between stack and catalyst replacement, PEM fuel cells are not
sufficiently durable to penetrate most markets in large numbers. The electricity generation efficiency
of a PEM fuel cell is projected to increase to 36 percent by 2030, while combined efficiency for
electricity and by-product heat is expected to range between 50 and 65 percent if all electricity
and heat are used. At a delivered hydrogen cost of $2 to $3 per kilogram ($17.54 to $26.32 per
million Btu), the fuel component of the cost of electricity generation is expected to range between
14 and 21 cents per kilowatt-hour, which would not be competitive with projected central-station
delivered electricity prices of 10.5 cents per kilowatt-hour in 2030. Because construction costs
for hydrogen pipelines to all homes would be extremely expensive, a more likely option might
use the existing natural gas infrastructure and on-site natural gas steam reforming. The cost of
that option is currently considered too high, at up to $40 per million Btu; additional research and
development of small-scale steam methane reforming will be required to bring delivered fuel cost
under $2 per kilogram of hydrogen (USEIA 2008b).
The U.S. Department of Energy estimates the cost of a fuel cell system would have to be in
the range of $30 to $45 per kilowatt for it to be competitive with internal combustion engines, a
substantial cost reduction, most of which is expected to be achieved through mass production on
the order of 500,000 vehicles per year (Ekins, Hawkins, and Hughes 2010, 51). One study from
2002 suggested the cost of a complete hydrogen fuel cell vehicle in 2007 would be $36,500. The
range of costs for 2015 to 2030 has been estimated at $18,000 to $34,000, with some vehicles
cost-competitive and others costing 15 to 20 percent more than comparable internal combustion
 
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