bio fuel
More recently, people have learned to process biomass to make fuel. This is called biofuel . Biofuel is created from crops, such as corn or algae. Biofuel is unique among renewable energy sources. This is because it is liquid. Unlike solar energy, for example, biofuels can be used in a car Figure below . Biofuels burn more cleanly than fossil fuels. They create less pollution and less carbon dioxide. Biofuels, such as ethanol, are added to gasoline. This cuts down the amount of fossil fuels that are used.