Stealth Wind Turbines Avoid Erasing Aircraft From Radar

A Danish company has demoed the first stealthy wind turbine that uses similar materials to stealth aircraft

Stealth Blades

Just turbine blades in the windQinetiQ

Wind turbines can be a radar operator's worst nightmare. By scrambling radar waves as blades spin faster or slower, large wind farms are sometimes capable of erasing airplanes from radar screens completely. But a Danish wind turbine company and a UK defense contractor may have found a solution by unveiling the first "stealth" wind-turbine blade last month.

Danish company Vestas and UK contractor QinetiQ constructed the wind turbines with radar-absorbing materials that included glass-reinforced epoxy and plastic foam, not the concept used in stealth aircraft. That produced a smaller signature during testing of a wind turbine with two stealth blades.

Such stealth technology may help wind farms avoid problems with short-wave radar. But a Homeland Security study last year found that the technology still falls short in preventing interference with long-wavelength L-band radars used by U.S. air security. A Vestas representative countered the study by telling Technology Review that the company has also demonstrated an L-band radar absorber.

Concerns over aviation radar interference have already held up development of many wind farms worldwide, including a 130-turbine farm in Massachusett's Nantucket Sound. They also compelled the UK government to join Raytheon Canada in trying to modify air-traffic control systems so that they can recognize and ignore wind farm radar signatures.

Still, a final solution may only arrive when older radar systems get upgraded and become more capable of dealing with wind turbine signatures.