Hybrid automobiles derive their energy from two or more sources, such as gasoline and electricity. They are low- or zero-emission vehicles and greatly reduce or eliminate the toxic carbon emissions that are by-products of gasoline-powered internal combustion engines.

Hybrid vehicles combine electric motors and internal combustion engines in such a way that their drive shafts can be powered by the gasoline engine, by the lithium-ion batteries of their electrical engines, or by a combination of the two. Although such vehicles existed as experimental prototypes as early as the late nineteenth century, they did not become commercially viable until the last quarter of the twentieth century, when fuel shortages, problems with air pollution, and concern over global warming converged to make fuel-efficient, nonpolluting vehicles attractive to the public.

The Japanese automobile company Toyota launched the first mass-produced hybrid, the Prius, in 1997 (Bethscheider-Kieser, 2008). Although this vehicle was not expected to attract many buyers, its initial American reception after it was introduced to the U.S. market in 2000 was enthusiastic. Toyota increased production and moved toward the manufacture of an aerodynamic Prius the size of Toyota's Corolla that would travel more than 21 kilometers on a liter of gasoline. Soon, Honda was producing comparable hybrids. People who wanted to buy a Prius often had to wait four to six months to have their orders filled. Prius sales in the United States doubled between 2003 and 2004, and they doubled again in 2005. By 2007, some 250,000 hybrids were sold in the United States.

Hybrids generate much of their own power and are essentially low- or zero-emission vehicles. Although their internal combustion engines can provide power in ways comparable to those of more conventional vehicles, these vehicles derive much of their power from a lithium-ion battery pack that is continuously charged and recharged while the vehicle is operated by its gasoline-powered engine and by the friction caused in normal braking. This regenerative process permits hybrids to deliver higher mileage in stop-start, urban driving than in long-distance, highway driving.

The key to producing hybrid vehicles that will deliver over 40 kilometers to a liter of gasoline is the development of increasingly light, rechargeable lithium-ion batteries. Toyota and other manufacturers have already developed lithium-ion batteries that do not encroach upon the vehicle's interior space, as earlier versions of such batteries did.

A number of automobile manufacturers have produced electric cars, "plug-in" vehicles that usually have ancillary gasoline-powered engines. Most of these vehicles must be plugged in for periods of from four to six hours for recharging. Most of them have a limited range, generally at best about 160 kilometers, and some are incapable of operating at interstate speeds. Despite these limitations, many such vehicles are in service with the United States Postal Service and other groups. They are practical if they are required to be in service for eight or ten hours a day, after which they can be plugged in to have their batteries recharged before the next work day.

Hydrogen vehicles have also been developed. These carry hydrogen in their fuel tanks, where it combines with oxygen taken in from the air and produces electricity to power the vehicle. The byproduct of this technology is water vapor, which results in zero emissions.

The Tata Motor Company of India has developed automobiles that will retail for under five thousand dollars and are directed toward buyers in India and China. It is doubtful that the initial Tata vehicles could meet U.S. safety standards. One of the most exciting Tata hybrids is being produced for developing nations. These vehicles, equipped with auxiliary gasoline engines, operate on compressed air using a technology developed by Guy Negre, a French engineer. They are extremely economical to operate.

The rapid development of hybrid vehicles has been stimulated by a number of compelling forces, not the least of which is the problem of the worldwide pollution being caused by the burning of fossil fuels. The toxic residues that the burning of such fuels produces are poisoning the environments of every nation in the world (Boschert, 2006).

Even if one ignores the threat posed by burning fossil fuels, society worldwide is exhausting the supplies of such fuels. In a world dependent for its transportation upon vehicles powered by various sources of energy, it is crucial that these sources must be both nonpolluting and renewable. It is unrealistic to assume that the contemporary world will drastically reduce its consumption of energy in the foreseeable future. Thus, the development of technologies that will make optimal use of renewable energy is perhaps society's greatest hope for the future.

References

1. Bethscheider-Kieser, Ulrich. Green Designed Future Cars: Bio Fuel, Hybrid, Electrical, Hydrogen, Fuel Economy in All Sizes and Shapes. Los Angeles: Fusion, 2008.

2. Boschert, Sherry. Plug-In Hybrids: The Cars That Will Recharge America. Gabriola Island, B.C.: New Society, 2006.

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