Air Force looks to solve wind farm radar interference

The Air Force is looking to hire a software modeling company to develop a tool to get around a growing problem: radar interference caused by wind turbines.

Officials at Peterson Air Force Base, Colo., announced that they plan to award a two-year research and development contract to Analytical Graphics Inc. to develop a specialized  version of the company’s Radar Obstruction Evaluation Model/Simulator that is to be ready for government validation when it’s completed. The value of the contract is estimated to be $450,000.

AGI’s simulator, known as ROEMS, works with the company’s Systems Tool Kit modeling program, which has been used by NASA, the Marine Corps and the Air Force on projects ranging from network architecture analysis to airborne early warning, according to the company. The new simulator, to be called ROEMS II, will be a “straight-forward configuration control architecture” to help radar system designers account for wind turbine interference, the Air Force’s announcement said.

Radar interference from wind turbines isn’t a new problem, but it’s becoming more common as wind farms proliferate. Any structure, such as a building or TV tower, can reflect radar. Wind turbines can complicate things depending on their height, size of blades and the speed of their rotation. The amount of interference can range from none at all to significant, and could depend on the sensitivity of the radar equipment.

A case study in the December 2012 Air Force Law Review notes that the problem cropped up at Travis Air Force Base, Calif., when a radar system was upgraded from analog to a more precise digital system. Controllers began seeing “persistent but non-existent weather cells” and aircraft they were tracking disappear and reappear on their screens. The problem was coming from a farm of more than 700 wind turbines southeast of the base.

That kind of obstruction can affect not only air traffic control, but weapons testing and training, weather tracking and even microwave signals, according to a study commissioned by the Federal Aviation Administration. In addition to its effects on aviation and the military, the problem has stalled a number of wind turbine projects, which provide a source of alternative energy supported by the Energy Department.

DOE, FAA and the Defense and Homeland Security departments in April completed a two-year, $8 million study of wind-radar interference from turbines, in search of the most promising technologies for mitigating the problem. After the tests, DOE said it was developing a long-term plan.

A potential mitigation technique is simply to ensure that turbine don’t operate near high-radar areas, but that could limit their development. Other possible steps, according to a DOE fact sheet, include coating them with material that will minimize their radar signature and optimizing software to compensate for signals from wind farms.

With ROEMS II, the Air Force and AGI could significantly help with the latter approach.