Basic
Renewable energy sources include renewable non-fossil energy sources such as wind, solar, geothermal, hydro-power and energy from biomass/wastes. The later refers to electricity generated from the combustion of wood and wood wastes, other solid wastes of a renewable nature, biogas, liquid bio fuels and from municipal solid waste incineration. Renewable resources replenish naturally and are virtually inexhaustible. They are distinct from non-renewable energy sources which are considered to be finite, exhaustible resources.
Origin
Mankind's use of renewable energies can be considered to have started when humans learned to control the use of fire. Wood and other materials were burnt to provide heat and for cooking food.
As civilization developed, energy from natural resources such as wind, sun and water was used.
Wind power was used to propel boats on the Nile as early as 5000BC and by 200BC simple windmills were pumping water in China. Palae-Indians in North America used geothermal energy from hot springs for warmth over 10,000 years ago. Solar energy was understood and used by ancient civilizations such as the Romans.
US Department of Energy (DOE)
Some forms of renewable energy, such as tidal energy are still in the infancy. However others, such as wind and biomass, are very developed. Biomass is now the largest renewable energy contributor. Wind capacity in 2007 was 50 times its 1990 level and continues to grow rapidly.
