Earlier this year, a study done on the visual and aural impact of wind farms in the EU showed that, depending on how close the turbines are built to houses, the noise produced by the whooshing blades is viewed as an annoyance by some people. Even if this percentage is relatively small, for those people affected it could be a genuine problem.
Science Daily gives us the details on work being done in Germany that would make wind turbines quieter:
'Like the Whining of a Mosquito'
A group of German firms, lead by Fraunhofer-Gesellshaft is developing an alternative to passive damping systems currently deployed in some wind turbines for noise reduction. The goal is to reduce the monotone sounds caused by vibrations in the gearbox, which one of the researchers says people find particularly unpleasant, "rather like the whining of a mosquito".
'Anti-Noise' Counteracts Vibrations
To do this the group has developed an active damping system which reacts "autonomously to any change in frequency and damp the noise—regardless of how fast the wind generator is turning"
The key components of this system are piezo actuators. These devices convert electric current into mechanical motion and generate "negative vibrations", or a kind of anti-noise that precisely counteracts the vibrations of the wind turbine and cancels them out. The piezo actuators are mounted on the gearbox bearings that connect the gearbox to the pylon.
via :: Science Daily and :: Fraunhofer-Gesellshaft
Queen of England Buys World's Biggest Wind Turbine (7.5 Megawatts!)
Cost of Wind Power Turbines Is SkyRocketing
Common Eco-Myth: Wind Turbines Kill Birds