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.

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Hyundai has a growing stable of alternative fuel cars and the Kona electric will be joining the Ioniq and the soon-to-arrive Nexo fuel cell vehicle as the Korean company steers its way to the future.
Built in Britain at Nissan's Sunderland factory, the Leaf has pioneered electric motoring in the UK - a sector of the car market which last year grew by more than 30 per cent with some 120,000 so-called alternative fuel cars sold and now accounting for almost five per cent of new car registrations.
OPEC noted that competition for ICE cars will come from alternative fuel cars in general and not only from EVs.
18,000 were sold in year than were last June Electric, hybrid and other alternative fuel cars only account for 4.4 per cent of all cars sold, but that's up from 3.2 per cent just a year ago.
Electric, hybrid and other alternative fuel cars still only account for 4.4% of all cars sold, but that's up from 3.2% just a year ago.
The vehicle is to be priced at USD50,000 before government incentives designed to speed the adoption of alternative fuel cars.
China plans to spend $L5 trillion in seven strategic sectors, including alternative energy, alternative fuel cars, and high-end equipment manufacturing (including high-speed rail and aviation).
The 12th Five Year Plan (2011-2015) targets sustainable economic growth, with an emphasis on domestic demand and seven strategic industries, including energy saving & environmental protection, alternative fuel cars and bio-technology.
Peter Rask, Volvo Car UK's managing director, said: "When we started the Emission Equality campaign, it was clear to us that the discounts offered to hybrid and alternative fuel cars were out of date and unfair to the many thousands of motorists who'd decided to take a different technical route to achieving a lower level of emissions.
Another objective is ending oil dependence in transport via a shift to electric, hydrogen and alternative fuel cars. There should be zero-emission buildings and a smart interconnected electricity network.
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