Gasohol, a blend of nine parts unleaded petrol and one part alcohol (ethanol or methanol), used extensively in some countries to reduce the cost of petrol as motor fuel. Raw materials for methanol production are coal and organic wastes, especially waste-wood products, while ethanol may be distilled from grain, sugar crops, or almost any starchy plant. Although in most of the world in the early 1980s it remained more expensive than petrol, gasohol is derived from renewable sources.
Alcohol was used interchangeably with petrol in the first internal-combustion engines in the 1870s, and petrol-alcohol blends have been used periodically in Europe when oil was in short supply. Two petrol-alcohol blends, alcoline and agrol, were sold in the United States in the 1930s but were unable to compete successfully with low-cost petrol. The oil shortages of the 1970s prompted a revival of interest in alcohol blends, an interest further increased after 1985 by restrictions on leaded petrol. Gasohol can be used without modifying the carburettor, ignition timing, or fuel lines of a car, and has a slightly higher octane rating than ordinary unleaded regular petrol.