Ethanol

Interest in alternative fuels began with the realization that the supply of non-renewable fossil fuel is not infinite, a fact which has important economic and environmental consequences. For example, national dependence on foreign petroleum reserves creates economic vulnerabilities. In the United States, approximately 40% of the national trade deficit is a result of petroleum imports.

Environmentally, fossil fuel burning has negative consequences for local and global air quality. Locally, it causes high concentrations of ground-level ozone, sulfur dioxide, carbon monoxide, and particulates. Globally, fossil-fuel use increases concentrations of carbon dioxide, an important greenhouse gas.