Environmental Engineering Reference
In-Depth Information
ered, the total power generation capacity would be several times greater
than the current U.S. power generation.
Parked fuel cell cars could be plugged into the grid to generate pow-
er. If only a small percentage of drivers used their vehicles as power plants
to sell energy back to the grid, many of the power plants in the country
could be closed.
However, if the major source of hydrogen is reformed natural gas,
the cost of generating electricity with a low-temperature fuel cell would
be about $0.20 per kilowatt-hour. This is more than double the average
price for electricity. It would also produce 50% more carbon dioxide emis-
sions than the most efficient natural gas plants which are combined cycle
natural gas turbines. Low-temperature fuel cells operating on natural gas
are not as efficient at generating electricity. A stationary fuel cell system
achieves high efficiency by cogeneration.
But, cogeneration would add to the complexity of the vehicle. Con-
necting a vehicle to the electric grid will also require some additional elec-
tronics. Extracting useful heat would involve new ductwork and possibly
heat exchangers. This could be a problem for existing buildings, where
parking may not be adjacent to heating units. Most homes could probably
use the heat from a 1 kilowatt (kW) fuel cell, but a car will probably have
a 60/80-kW fuel cell.
Home electricity generation with either a stationary or a mobile fuel
cell may not provide any cost savings that would jump-start commercial-
ization. Also, a method is needed to get hydrogen to your home or office
to power the fuel cell after your car's onboard hydrogen is consumed. For
relatively small amounts of hydrogen, bottled hydrogen is likely to be ex-
pensive per kilogram. It could also be expensive to generate hydrogen on-
site. Hydrogen generation and purification units may be too expensive for
home use and local electricity and natural gas prices are much higher than
for larger users.
FUEL CELL BENEFITS
Fuel cells are the cleanest and most efficient technologies for gener-
ating electricity from fossil fuels. Since there is no combustion, fuel cells
do not produce any of the pollutants commonly emitted by boilers and
furnaces. For systems designed to consume hydrogen directly, the only
products are electricity, water and heat.
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