Vestas reports development of "stealth" wind blades

The blades, covered with radar-absorbing materials developed with QinetiQ, achieved a targeted reduction in radar cross-section of approximately 99 percent.

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Vestas Wind Systems A/S (Randers, Denmark) reported on June 29 that it has successfully tested a full-scale “stealth” rotor on a turbine, paving the way for wind power plants to be located near many military, airport and other radar systems without interfering in their operations.

The stealth turbine test, which was conducted at a U.K. customer site with technology partner QinetiQ, is part of an ongoing research collaboration that began in 2006. Preliminary test results showed that a Vestas V90 turbine with stealth rotor achieved a targeted reduction in radar cross-section of approximately 99 percent, or 20 decibels, compared with standard turbines.

“Our testing has demonstrated that we have successfully adapted military stealth technology to make Vestas wind turbines viable for placement in many locations that have been restricted by radar concerns,” said Vestas Technology R&D president Finn Strøm Madsen.

“This is a critical step toward the commercialization of stealth turbines and holds potential to open a significant number of wind power locations for Vestas customers.”
With an estimated 20 GW of wind power capacity currently blocked worldwide by concerns about radar interference, Vestas says its stealth turbine research has validated a potentially important addition to the operational, technical and political mitigation tools available today.

The stealth turbine solution uses a portfolio of radar-absorbing materials that are integrated into the current manufacturing processes for turbine components and can be designed to operate at aviation and maritime frequencies. These modifications do not affect the performance or appearance of the turbines, which meet current visual standards.

The full-scale test announced today follows more than five years of research collaboration with U.K.-based QinetiQ to develop and improve the application of military stealth technology to wind turbines. Early laboratory and wind tunnel testing progressed to initial site testing of a single, 44m blade in late 2009. Additional design optimization led to process cost reductions and quality improvements that were verified by the full-scale testing of a three-blade stealth turbine in 2011.