Alternative fuel vehicle

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Alternative fuel vehicle

Conventional fuels such as gasoline and diesel are gradually being replaced by alternative fuels such as gaseous fuels (natural gas and propane), alcohol (methanol and ethanol), and hydrogen. Conventional fuels can also be modified to a reformulated gasoline to help reduce toxic emissions. Technological advances in the automotive industry (such as in fuel cells and hybrid-powered vehicles) are helping to increase the demand for alternative fuels.

Vehicle emissions from natural gas and propane are expected to be lower and less harmful to the environment than those of conventional gasoline. Because natural gas and propane are less complex hydrocarbons, the levels of volatile organic compounds and ozone emissions should be reduced. Both of these fuels are introduced to the engine as a gas under most operating conditions and require minimal fuel enrichment during warm-up. Leaner burning fuels, they also achieve lower carbon dioxide and carbon monoxide levels than gasoline. However, because they burn at higher temperatures, emissions of nitrogen oxide are higher. An important property of gaseous fuels is their degree of resistance to engine knock. Because of their higher-octane value relative to gasoline, there is less of a tendency for these fuels to knock in spark-ignition engines. To achieve the optimal performance and maximum environmental benefits of natural gas and propane, technological advancements must continue to reduce the costs of dedicated vehicles to be competitive with conventional vehicles, and the necessary fueling infrastructure must be ensured.

The most significant advantage of alcohol fuels over gasoline is their potential to reduce ozone concentrations and to lower levels of carbon monoxide. Another important advantage is their very low emissions of particulates in diesel engine applications. In comparison with hydrocarbon-based fuels, the exhaust emissions from vehicles burning low-level alcohol blends (such as gasohol containing 10% alcohol by volume) contain negligible amounts of aromatics and reduced levels of hydrocarbons and carbon monoxide but higher nitrogen oxide content.

Exposure to aldehydes, in particular formaldehyde which is considered carcinogenic, is an important air-pollution concern. The aldehyde fraction of unburned fuel, particularly for methanol, is appreciably greater than for hydrocarbon-based fuels; therefore, catalytic converters are required on methanol vehicles to reduce the level of formaldehyde to those associated with gasoline.

Hydrogen-powered vehicles can use internal combustion engines or fuel cells. They can also be hybrid vehicles of various combinations. When hydrogen is used as a gaseous fuel in an internal combustion engine, its very low energy density compared to liquid fuels is a major drawback requiring greater storage space for the vehicle to travel a similar distance to gasoline. Although hybrid vehicles can be more efficient than conventional vehicles and result in lower emissions, the greatest potential to alleviate air-pollution problems is thought to be in the use of hydrogen-powered fuel cell vehicles. Though currently very expensive, fuel cells are more efficient than conventional internal combustion engines. They can operate with a variety of fuels, but the fuel of choice is gaseous hydrogen since it optimizes fuel cell performance and does not require on-board modification.

Conventional gasoline is a complex mixture of many different chemical compounds. The U.S. Clean Air Act Amendments (CAAA) have served to increase interest in using regulated changes to motor fuel characteristics as a means of achieving environmental goals. The reformulated gasoline (RFG) program was designed to resolve ground-level ozone problems in urban areas. Under this program, compared to conventional gasoline, the amount of heavy hydrocarbons is limited in reformulated gasoline, and the fuel must include oxygenates and contain fewer olefins, aromatics, and volatile organic compounds.

References in periodicals archive ?
Higher diesel and alternative fuel car sales helped the average new car CO emissions fall by 4%.
Likewise, the Database of State Incentives for Renewables and Efficiency (DSIRE) is another free online resource that lists state and federal incentives for buying an alternative fuel car, greening up your home or otherwise embracing energy efficiency.
If every other car is an alternative fuel car, then 90 million gallons a day is a realistic demand in the coming years.
Powered by hydrogen, Ford claims that this experi-mental vehicle is the most advanced alternative fuel car in the world.
Automotive Internet pioneer Autobytel named the all-new Ford Fusion its 2013 Car of the Year while the all-new Ford C-MAX has earned Alternative Fuel Car of the Year honors.
Classified as an alternative fuel car, that figure means that this Civic can navigate London at no extra cost and falls into the lowest tax categories.
Powered by hydrogen, the Blue Oval claims this experimental vehicle is the most advanced alternative fuel car in the world.
The atrocious British weather put paid to the most advanced alternative fuel car in the world yesterday as Ford unveiled its latest hydrogen-powered vehicle.
And if it is safe, when can we take an alternative fuel car or van through the Channel Tunnel?
This event is the world's largest Earth Day celebration with 60,000 visitors and an alternative fuel car show in Balboa Park.
When evaluating alternative fuel cars or electric vehicles, 45 percent of women and 35 percent of men would consider it for their next purchase.

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