There are several forms of alternative power. Alternative power has derived its name from the use of sources other than fossil fuels.
Geothermal energy comes directly from the natural heat generated within the interior of the earth.
This heat is released through the crust from the mantle at various hot springs and geysers. Either naturally occurring steam from an extant water source or steam created when water is pumped to the heat source artificially can be used to run a steam turbine and thus produce electric power. Or the heated water may be pumped directly to buildings through pipes. Solar power is energy captured from the sun, which is used either in a passive or an active energy system. The passive form of solar heating involves heating buildings through proper placement in sunny places and the use of water drums.