The production of wind energy creates no air pollution and, if the turbines are sited properly, has minimal environmental impact. By including wind generation in its energy mix, TVA and the distributors of TVA power have introduced the first commercial-scale use of wind power to generate electricity in the Southeastern United States.
TVA’s wind site, Buffalo Mountain Wind Farm near Oak Ridge, TN, has fifteen turbines owned and operated by Invenergy. Three smaller TVA-owned test turbines were decommissioned in 2021 after maintenance issues rendered them inoperable in 2009. The site is on a two-mile ridgeline facing southwest, the predominant wind direction at the location.
The Buffalo Mountain Wind Farm has 27 megawatts of generation, which is enough to power over 2,000 homes. The turbines are about 260 feet tall, and the blades are 135 feet long. They have a capacity of 1.8 megawatts each. Generally, the higher the tower, the better the access to the wind.
A turbine and switchgear are mounted at the top of each tower in a casing called a nacelle, and blades are attached to the turbine. The turbines use moving air to produce power by transferring the wind’s momentum to the rotor blades and localizing that energy in a single rotating shaft. The larger turbines rotate at about 15 revolutions per minute. Transformers in the nacelles step up the power to 35 kilovolts (kV), and it’s stepped up again to 161 kV at the substation located on the mountain. The substation connects to an existing TVA transmission line.
Energy is generated when the wind speed reaches about 10 miles per hour, and a speed of 25 miles per hour allows the turbines to generate at their rated capacity. They shut down when the wind exceeds 55 miles per hour.
Large modern turbines are very quiet. At distances of more than 650 feet, the swishing sound of the rotor blades is usually masked completely by wind noise in the leaves of trees or shrubs. The turbine sites are distant enough from neighbors so that people won’t hear any sound at all unless they’re standing close to the towers.