If it carries just one passenger, it gets only 31 passenger-miles per gallon. Overview As the number of people in the world keeps growing, so does our need for energy. Some energy sources, specifically fossil fuels like coal and oil, are in limited supply. Once we use up what's in the ground, they will be gone forever. Other energy sources, such as wind, water power, and solar energy, are called renewable energy, because they will regenerate over and over again as we use them.
Ethanol is one form of renewable energy that is becoming widely used.
Ethanol is a form of alcohol that can be burned in engines just like gasoline. But unlike gasoline, which is made by distilling crude oil, ethanol is made from the starchy parts of plants. Most ethanol in this country is created through fermentation of corn. Microscopic yeast cells break down the starch and water, creating ethanol and carbon dioxide gas. In addition to being a renewable fuel, ethanol helps to reduce air pollution.