Renewable Energy is energy derived from resources that are regenerative or for all practical purposes cannot be depleted.For
this reason,
renewable energy sources are fundamentally different from fossil fuels, and do not produce as many greenhouse gases
and other pollutants as fossil fuel combustion. Mankind''s traditional
uses of wind, water, and solar energy are widespread in developed and
developing countries; but the mass production of electricity using
renewable energy sources has become more commonplace recently,
reflecting the major threats of climate change, exhaustion of fossil fuels,
and the environmental, social and political risks of fossil fuels.
Consequently, many countries promote renewable energies through tax
incentives and subsidies.
Renewable energy accounts for about 1/10th of the world''s primary energy supply,but the technical potential is large enough to cover even the projected
energy consumption in 2100 many times over(see below). Renewable
technologies such as geothermal and hydropower are often economically
competitive with nonrenewable energy sources. Other technologies such
as solar power are more expensive, although future costs may decline to
a fraction of current levels.