'Oxygenates' are fuels containing oxygen in their molecules. The most important are the alcohols methanol and ethanol. Adding these oxygenates to petrol reduces the quantities of carbon monoxide and hydrocarbons that are produced.

In some tropical countries, there is plenty of agricultural land. People grow sugar cane, maize, bananas and palms. They can be fermented and distilled to produce ethanol that supports cars.

In Brazil, most motar cars use gasohol as their fuel. Gasohol is a mixture of petrol (80%) and ethanol (20%). It can be used in normal cars without modication of their engines. Since ethanol has different calorific value and burning characteristics ehwn compared with petrol, the cars that use pure ethanol as a fuel need to have their engines modified.

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