Large turbines generating electricity in a radar line of sight can harm the ability of air defense radars to detect and track aircraft or other aerial objects, the U.S. Department of Defense said Thursday in a new study.
The only way to make sure that U.S. forces can perform their air defense missions is to avoid putting the wind turbines in the line of sight of the radars, said the report submitted to the Senate and House Armed Services committees.
Efforts have started to find other ways but they “require further development and validation” before they can be used, given that some turbines with rotating blades reach 500 feet high, the report said.
“The numbers, height and rotation of these wind turbines present technical challenges to the effectiveness of radar systems that must be carefully evaluated on a case-by-case basis to ensure acceptable military readiness is maintained,” the report said.
At least a dozen wind farm projects in Illinois, Wisconsin and North Dakota have been stalled pending the completion of the military study.
Minnesota is fourth in the nation in wind energy installed, and Wisconsin is 20th, according to the American Wind Energy Association, a Washington trade group.
Testing has demonstrated that wind farms can “degrade target tracking capabilities” because they can cause shadowing and clutter on radar, said the study, which was requested in the National Defense Authorization Act passed by Congress late last year.
Randall Swisher, executive director of the trade group, said he was disappointed in the Defense Department report, calling it incomplete and lacking mention of ways to mitigate wind turbines’ effects on radar, such as relocating turbines or upgrading radar systems.
Decades of experience indicate that wind turbines and radar can coexist, Swisher said.
“The American wind energy industry will continue to work collaboratively with government and others on efforts to constructively address challenges and refine solutions,” he said. “We need to further develop clean, renewable energy sources like wind to reduce dependence on imports and increase our energy security.”
The association said it welcomed recent Federal Aviation Administration approval of 614 applications for individual wind turbines in Wisconsin, Minnesota, Illinois and South Dakota that will produce more than 1,000 megawatts of power, enough to power about 250,000 homes.
The Department of Defense study said wind turbines located close to military training, testing and development sites and ranges would “adversely affect” the military’s ability to perform those missions.
Associated Press writer Robert Imrie in Wausau contributed to this report.
ON THE NET
U.S. Defense Department windmill farms study: http://www.defenselink.mil/pubs/pdfs/WindFarmReport.pdf
By John Hartzell, Associated Press
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