It's a shame when any bird is killed by colliding with the spinning blades of a wind turbine, but it's particularly sad when that bird is a protected species. With that in mind, scientists are developing technology that could both deter eagles away from turbines, and detect when they hit the blades.
The main component of the system, designed by an Oregon State University team led by Prof. Roberto Albertani, incorporates a video camera mounted at the base of the turbine tower, vibration sensors mounted at the base of each blade, and an acoustic sensor located on the turbine's generator housing.
The idea is that when a bird strikes one of the blades, the impact is detected by the vibration sensor on that blade. Footage recorded by the camera at that time, along with audio of any bird cries recorded by the acoustic sensor, is then used to determine what sort of bird (or bat) was involved.
While this won't stop eagles from flying into the blades, it will at least let wildlife officials know exactly how many of the birds are being killed by individual turbines. Currently, this sort of knowledge is gained by inspecting carcasses located on the ground beneath the turbines, although there are problems with this approach – carcasses can be dragged away by scavengers, plus such surveys aren't feasible in remote locations, in areas with dense shrubbery, or at offshore turbines.
In tests of a basic version of the system, eagle strikes were simulated by shooting tennis balls at wind turbine blades. "General results from 29 field tests with blade strikes showed positive detection and confirmation 14 times," says Albertani. "Likely the impacts not detected were low-energy events. It is strongly believed the success rate can be significantly increased."
But what about keeping those eagle strikes from happening in the first place? Well, that's where another component of the system comes into play.
Using a computer-connected turbine-mounted camera, it would automatically determine if an approaching bird was an eagle, and if it was heading towards the blades. If that was deemed to be the case, then the computer would activate a ground-based deterrent consisting of randomly moving, brightly-colored facsimiles of people. It is hoped that based on eagles' aversion to humans, this would cause the birds to alter their course.
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