WIND ENERGY

The Earth is unevenly heated by the sun.  Dry land heats up (and cools down) more quickly than the seas do.  This differential heating drives a global atmospheric convection system creating windy conditions.  Windmills have been used for over 2000 years to power machinery, pump water, grind grain, etc.  Wind turbines to generate electricity are a relatively new wind energy development and are growing quite rapidly.  By 2010 the World Wind Energy Association expects 160GW of capacity to be installed worldwide, up from 73.9 GW at the end of 2006, implying an anticipated net growth rate of more than 21% per year.