A wind energy system transforms the kinetic energy of wind into mechanical or electrical energy that can be harnessed for practical use. Mechanical energy, most commonly used for pumping water in rural or remote locations, powers the “farm windmill” still seen in many rural areas of the U.S.
Wind turbines generate electricity in a straightforward way: wind moves the blades of the turbine, which spin a central shaft. The shaft connects to an electrical generator, often located at the top of the tower, which produces electricity. Wind turbines are deployed at homes, farms, businesses, utility-scale wind farms, and other locations.
There are two basic designs of wind turbines: vertical-axis (“egg-beater” style) and horizontal-axis (propeller-style) machines. Horizontal-axis wind turbines are most common today, constituting nearly all of the utility-scale (100 kilowatts (kW) capacity and larger) turbines in the global market. Small-scale turbines (50 kW capacity and under) are used to power isolated communities and other areas where large turbines are not feasible. Today turbines with capacities as large as 5 megawatts (MW) are being tested.
Wind farms may also be located offshore, where the average wind speed is much higher than on the land. Most offshore wind turbines are fixed to the ocean floor, while some newer models float on platforms.
For more on wind power, visit the Department of Energy’s wind overview.
- Wind power provided 35% of all new U.S. electric capacity over the last four years. (American Wind Energy Association (AWEA))
- In Iowa and South Dakota, wind now generates around 20% of the states’ electricity needs. (AWEA)
- The U.S. wind industry installed 34% more megawatts during the first half of 2012 than it did during the first half of 2011. (AWEA)
- The U.S. wind industry installed 1,200 MW during the second quarter of 2012, bringing the total U.S. wind power capacity installations to 49,802 MW and 2012 installations to 2,896 MW (through the end of June 2012). (AWEA)
- As of the beginning of 2012, 38 states had utility-scale wind projects. Texas accounts for roughly 20% of U.S. wind energy with a capacity of 10,648 MW. Following Texas in wind are Iowa with 4,524 MW; California with 4,425 MW; Illinois with 3,055 MW; and Oregon with 2,820 MW. (AWEA)