Environmental Engineering Reference
In-Depth Information
for the general public, and the fuel tank in the car must be heavy and
bulky to contain the compressed natural gas, a major disadvantage for
long-distance driving. Additional weight causes a great reduction in the
number of miles per gallon of gasoline (or miles per cubic foot of
natural gas).
Because of the need to reduce the nation's dependence on petroleum,
automobile companies are making major efforts to produce hybrid gas-
electric and all-electric cars. In hybrid vehicles, the small gasoline engine
recharges the batteries. Hybrids have been available for about ten years,
but because they typically cost $3,000 to $4,000 more than a conven-
tional gasoline-powered car, they are still only one-tenth of 1 percent of
the cars on the road—360,000 of 250 million cars.
Within the next two to three years, hybrid cars will be available that
build on the effi ciency advantages of today's hybrid cars. By adding a
large and powerful battery, today's hybrid will be converted into a
plug-in hybrid in which the battery can be recharged by plugging its cable
into a standard electric outlet. Cars may have a retractable tail like
vacuum cleaners. The large battery increases the distance the car can
travel without recharging and further reduces energy use.
Within the past few years there has been a resurgence of interest in
all-electric vehicles powered by an array of large batteries in the vehicle.
The batteries can last for ten years, but the range of such vehicles is only
100 miles before the batteries need recharging, a serious limitation to
their use in a large country such as the United States. Unlike standard
car batteries that are based on lead, the batteries for electric vehicles are
fueled by lithium, an element whose abundance and availability are
uncertain. The majority of extractable lithium reserves are believed to
be in Chile and Bolivia, but smaller deposits occur in the United States,
Russia, Argentina, Brazil, Australia, and Tibet. And it has been predicted
that once lithium-ion batteries are in wide use, lithium will be recycled
from old lithium batteries to provide a stable source of the metal.
Because powerful lithium-ion batteries are very expensive, recharge-
able electric cars will likely cost $6,000 to $8,000 more than hybrids.
Automotive engineers are working feverishly to produce a low-cost
powerful battery. If battery costs are not signifi cantly reduced, electric
cars will not be a signifi cant part of America's automotive fl eet. Never-
theless, research is ongoing and has substantial federal fi nancial support.
Electric motors are more effi cient than gasoline motors: they need less
energy to do the same amount of work. At current electricity prices,
running an electric vehicle would cost the equivalent of 75 cents a gallon.
