New additive may boost mileage and power, cuts pollution

Washington D.C., Aug. 24 -- A gasoline additive that may be able to dramatically increase mileage and engine power with less pollution was described here today at the 220th national meeting of the American Chemical Society, the world's largest scientific society.

Now being tested in three U.S. states and other countries, the additive, polyisobutylene, is a polymer that works differently than the oxygenates now widely used as gasoline additives. It is vastly more effective as well, according to its developers.

Polyisobutylene can produce a 10 percent increase in horsepower, a 20 percent increase in mileage, and a 70 percent decrease in emissions of such environmental pollutants as carbon monoxide, unburned hydrocarbons and nitrogen oxides, according to Paul Waters, Ph.D., a professor emeritus at American University in Washington, D.C. He is also a scientific advisor to General Technology Applications, in Gainesville, Va., the company that developed the additive.

Gasoline is comprised of hydrocarbons - chains of hydrogen and carbon atoms - of different lengths. When gasoline and oxygen are combined and ignited in a car's engine, the molecules of hydrogen, carbon and oxygen rearrange themselves to form carbon dioxide and water. This reaction releases the energy that drives the engine.

Air, the engine's source of oxygen, does not contain enough oxygen to react fully with gasoline, so some hydrocarbons remain unburned. The energy thus lost could be used to power the engine more efficiently, according to Waters. Unburned hydrocarbons - some of which may be carcinogenic - also add to pollution, he says.

To increase the amount of oxygen available for combustion, oxygenates such as MTBE are added to gasoline. But recent evidence of groundwater contamination has raised concerns about the use of MTBE.

In contrast to MTBE, polyisobutylene changes the
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Contact: Charmayne Marsh
y_marsh@acs.org
202-872-4445
American Chemical Society
24-Aug-2000