Alternative Energy Sources

Biomass—wood, dried animal dung, or materials left over from agriculture—is the oldest fuel used by people, and was initially utilized for space-heating and cooking food. These uses are still major energy sources in developing countries, especially in rural areas. Biomass can also be combusted in a boiler to produce steam, which can be used to generate electricity. The biomass of trees, sugar cane, and corn can also be used to manufacture ethanol or methanol, which are useful liquid fuels.