Alternatively fueled vehicles

DEFINITION: Vehicles fueled, wholly or partially, by energy derived from sources other than petroleum

The development of vehicles that operate efficiently using little or no petroleum-based fuel is an important part of efforts to address the problems of declining petroleum resources and the pollution caused by emissions from petroleum-based fuels.

Almost all of the fuel used for transportation in the United States is derived from petroleum. In California, a huge consumer of fuel to run its millions of vehicles, 12 percent of those vehicles used alternative fuel sources in 2021. As the world’s oil fields become depleted and reserves shrink, and as awareness grows regarding the harm to the caused by the burning of fossil fuels, the pressure to develop alternative fuels and vehicles that can operate using them has become intense. Since the late twentieth century, significant progress has been made in this area: Between 1970 and 2020, advances in automotive technologies decreased toxic vehicle emissions by an estimated 95 percent. These advances included the development of vehicles powered by non-petroleum-based fuels.

Auto manufacturers long resisted producing vehicles that would not be dependent on petroleum-based energy sources; for many years, they rejected alternative technologies in favor of the entrenched gasoline-burning internal combustion engine. Significant gasoline shortages in 1973 and 1979, however, clearly demonstrated the need for mass production of vehicles that could be powered by renewable resources. Whereas automobile companies and the petroleum industry had previously discouraged technologies related to the development of practical electric vehicles, many such corporations came to recognize the need to explore and encourage the production of alternative fuel sources.

Hybrid and Electric Vehicles

By the late twentieth century, automobile manufacturers, first in Japan but later in the United States and Europe, turned their attention to producing reasonably priced, fuel-efficient, nonpolluting vehicles. The most popular of such vehicles are hybrid vehicles; by 2010, nearly twenty versions of such vehicles were available commercially. Electric cars have also become more prevalent in the second and third decades of the twenty-first century. In 2023, there were 237 hybrid and electric car manufacturing businesses in the United States. This number increased by 10 percent from 2022.

Hybrids such as Toyota’s Prius and Honda’s Insight are powered by gasoline-fueled internal combustion engines in combination with electric motors. These motors, which receive their electricity from batteries, provide power for the automobiles, but when they run down, small internal combustion engines take over. The batteries in hybrid vehicles are recharged by the friction created every time the brakes are applied. The ranges of such vehicles—that is, the distances that they can be driven between refuelings—are comparable to those of conventional vehicles.

Plug-in electric vehicles have a much more limited range than do hybrids; most can be driven only about 160 kilometers (100 miles) before they require recharging. Such vehicles are useful for service within limited areas, where they can be driven for short periods and recharged when not in use. Recharging a plug-in electric vehicle’s batteries fully can take four to eight hours. Anticipated improvements in electric vehicle technology include drastic shortening of the time required to recharge batteries and enhancement of battery life to extend the vehicles’ range.

Other Fuels for Internal Combustion Engines

The conventional internal combustion engines found in most vehicles can often be run on nonpetroleum fuels or on mixtures of petroleum-based and other fuels. One frequently used alternative fuel is ethanol, an alcohol derived from plants that can be mixed with conventional gasoline. Such mixtures usually consist of 5 percent and 95 percent conventional gasoline, however, so the gasoline savings are negligible.

Another nonpetroleum fuel is hydrogen, which can be used to fuel slightly modified existing vehicles. As of 2021, more than 5,600 buses fueled by hydrogen were operating in the United States, Canada, Mexico, Brazil, Japan, Egypt, Iceland, and India. Most hydrogen-powered buses, however, were operated in China. In the United States, there were 87 hydrogen-fueled buses in 2021, only slightly more than 3 percent of all buses in the country. Hydrogen has the advantage of producing water as its sole emission, so it does not contribute to air pollution. The major problem with using hydrogen is that it is not readily available to consumers. Proponents of hydrogen as a motor vehicle fuel assert that successful solution of the problem of distribution might revolutionize how vehicles are fueled.

Although hydrogen is among the most plentiful elements in the universe, it is not available merely for the taking. Because it bonds with other elements, such as oxygen, it is a carrier of energy rather than a source of energy like petroleum or coal. To power a vehicle, hydrogen must pass through onboard fuel cells in which a chemical reaction reduces water into its component parts, hydrogen and oxygen. This hydrogen, available in a free state, is converted to electricity and used to fuel the vehicle. When hydrogen is used in its gaseous state, leakage is a problem. Hydrogen can be liquefied and can also exist in powder form. Its most efficient use in fueling vehicles is usually in its gaseous or liquefied form.

Liquefied natural gas, which is less expensive to produce than gasoline, is used to fuel some fleets of taxicabs and other commercial vehicles. Liquefied petroleum gas, or propane, is also used to provide the power for many commercial fleets. It is less expensive and less polluting than regular gasoline. Research and development of alternative fuels continued in 2023. Biobutanol, dimethyl ether, methanol, and renewable hydrocarbon biofuels are considered emerging alternative fuels by the United States Department of Energy.

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