Wind and water
power result from the convective action of the sun, the rotation
of the earth, and the evaporation of water. The radiant energy of
the sun heats the earth's atmosphere, creating thermal updrafts
which, in effect, turn that energy into the mechanical energy of
the wind. The wind currents are then directed and magnified by the
rotation of the earth. The resulting wind power was traditionally
utilized in this country to sail ships, pump water and grind grain,
but is now primarliy used to generate electricity.
Water that is
evaporated by the sun rises with the thermal updrafts, is carried
by the wind currents and then condenses and falls as rain into streams,
rivers and lakes. As this water courses through streams and falls
form higher to lower elevations, it creates the force, or head,
that drives hydro turbines to create hydroelectric power.
For an index
of manufacturers of wind and small-scale hydroelectric equipment
and systems, see the Renewable
Energy Manufacturers Index.