Biofuels are considered a renewable energy source because they can regrow during the course of a person's lifetime. However, they are only renewable as long as they are used at a slower rate than they can regrow. Biofuels have historically come from both plants and animals. Today, animals are no longer harmed as fuel sources. Some current examples of biofuels include using wood, crops, manure, and some garbage to produce energy.
The most common form of biofuel use is wood burning. For thousands of years people have burned wood for heating and cooking. In recent centuries, other types of biofuels have been developed. These include,
• peat (decaying vegetation)
• oils such as whale oil
• biodiesel from cooking oils
• alcohol derived from corn, sugar, and other plants.
