Wind turbines in the United States have grown in both average height and generating capacity over the past decade, according to the Energy Department’s Energy Information Administration (EIA).
Wind turbine capacity is based largely on blade length, and taller turbines are able to have longer blades and access to better wind resources at greater heights.
Wind turbines accounted for 8 percent of the operating electric generating capacity in the United States in 2016, surpassing hydropower as the renewable technology with the largest installed generating capacity.
However, because of the way wind and hydropower electricity generators operate, hydropower still provides more electricity than wind does, totaling six and seven percent of the U.S. total, respectively, in 2016.
The largest turbines currently installed in the United States have generating capacities of 6 megawatts, according to the EIA. These turbines are part of the Block Island Wind Farm in Rhode Island, the only operating utility-scale offshore wind turbines in the United States.
Two offshore wind farms are planned to come online in the near future — the Icebreaker Offshore Wind project on Lake Erie in 2018 and the Coastal Virginia Offshore Wind project in Virginia in 2021.
EIA says that the largest onshore turbines in the United States are in Texas, with capacities of 4 megawatts each. One of the world's largest wind farms is also in Texas — the Horse Hollow Wind Energy Center has 420 wind turbines spread over about 47,000 acres. The project has a combined electricity generating capacity of about 735 megawatts.
Since 2012, the average height of wind turbines installed in the United States has been about 280 feet, or 80 meters. Before 2006, few wind turbines were as tall as 280 feet.
Wind speed typically increases with altitude and increases over open areas without windbreaks such as trees or buildings. Favorable sites for wind turbines include the tops of smooth, rounded hills, open plains and water, and mountain gaps that funnel and intensify wind.
In 2016, 40 states had utility-scale wind power projects, with the most generation in Texas, Iowa, Oklahoma, California and Kansas, according to the EIA. Combined, these five states produced about 55 percent of total U.S. wind electricity generation. Additional detailed information about wind turbine heights, capacity and other characteristics is available in EIA’s recently released annual survey of utility-scale electricity generators.