As simple as it sounds, wind energy is produced by turbines which harness the natural resource that is wind and convert it into electricity. Wind exists because the sun heats the surface unevenly, creating different pressure gradients which agitate and displace air at different temperatures in order to better equalize it. The use of wind power has historical significance; helping power sailboats which lead people to new discoveries and windmills which fed farms with water and milled grain.
Today, wind power is a significant means of producing sustainable, renewable energy. Wind turbines rotate with the presence of wind, powering generators in the shaft of the turbine which convert the wind's movement into electricity and relay it to the national grid. In the United States, single turbines in the most productive environments can produce enough electricity to power up to 600 homes per year. Wind speed, air density and the size of the turbine are all factors which determine productivity. Turbines have increased in size since large scale wind energy projects started in the 1980's, chiefly to boost their productive capacity. They can now reach heights of 700ft, with a turbine diameter of 370ft. As with other forms of renewable energy, government tax incentives and decreasing production and operational costs are making their impact on the market. While households don't stack wind turbines on roofs or in backyards, regions producing high yields of electricity have been more readily able to manage bills.