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.
With the inauguration of TVA’s expanded wind site in December 2004, when fifteen new turbines were added to the TVA wind site on Buffalo Mountain near Oak Ridge, Tenn. They are located near the three smaller turbines originally built in 2000. The site is on a two-mile ridgeline facing southwest, the predominant wind direction at the location.
The newer turbines expanded the capacity of the Buffalo Mountain site to 29 megawatts of generation, or enough to power about 3,780 homes. The turbines are about 260 feet tall, and the blades are 135 feet long. They have a capacity of 1.8 megawatts each. The three original turbines, with a capacity of 660 kilowatts each, are 213 feet tall, and their blades are 75 feet long. 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. The three smaller turbines are connected to the TVA system through a partnership arrangement with Clinton Utilities Board.
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.