Exhaust and Evaporative Emissions from Alcohol and Ether Fuel Blends

An experimental study was conducted at the U. S. Dept. of Energy's Bartlesville (Okla.) Energy Technology Center to evaluate the effects of four potential fuel extenders (each blended with gasoline) on fuel economy, exhaust emissions, and evaporative emissions from eight 1978 automobiles (three with California emission controls and five with Federal emission control systems). The gasoline/fuel extender blends were: 90% gasoline/10% ethanol, 90% gasoline/10% methanol, 93% gasoline/7% methyl tertiary butyl ether, and 93% gasoline/7% tertiary butyl alcohol.

In general, fuel economy decreased from 2.7 to 7.6% with each blend when compared to the base fuel (Indolene). Carbon monoxide emissions were reduced by 8 to 46%. Unburned hydrocarbon emissions were reduced by 5 to 32%, and oxides of nitrogen were either unaffected or increased depending on the fuel extender and the type of emission controls used. Evaporative emissions were generally increased--with the greatest increase (93%) observed with methanol and the lowest increase (5%) shown with tertiary butyl alcohol.