Ethanol

Ethanol has many positive features as an alternative liquid fuel. First, ethanol is a renewable, relatively safe fuel that can be used with few engine modifications. Second, its energy density is higher than some other alternative fuels, such as methanol, which means less volume is required to go the same distance. The third benefit of ethanol is that it can improve agricultural economies by providing farmers with a stable market for certain crops, such as maize and sugar beets. Fourth, using ethanol increases national energy security because some use of foreign petroleum is averted.

Another benefit, though controversial, is that using ethanol might decrease emissions of certain emissions. Toxic, ozone-forming compounds are emitted during the combustion of gasoline, such as aromatics, olefins, and hydrocarbons, would be eliminated with the use of ethanol. The concentration of particulates, produced in especially large amounts by diesel engines, would also decrease. However, emissions of carbon monoxide and nitrogen oxides are expected to be similar to those associated with newer, reformulated gasolines. Carbon dioxide emissions might be improved (-100%) or worsened (+100%), depending the choice of material for the ethanol production and the energy source used in its production.