Quiet wind energy: new technology adopted from the animal world
And suddenly people are talking about quiet wind energy: they are referring to the animal world, or more precisely the bird world. Combs that are attached to the wings of wind turbines, which have been copied from the wings of birds, so to speak, result in a noise reduction of several decibels.
Quiet wind energy has always been a political issue. Until now, there have always been technical obstacles to development in the wind energy sector. When the wind "breaks off" at the trailing edge of the blades of wind turbines, wind turbulence was created which, despite compliance with the noise protection ordinance, causes disturbing noise in stronger winds.
Manufacturers recognized this problem some time ago and conducted research at various levels to remedy it. Among other things, this has resulted in a type of "plumage", i.e. combs copied from the wings of birds. "The decrease in noise is 3 decibels on average. For a road, this would be comparable to a halving of road traffic," explains Xavier Falourd, an acoustician at Prona SA, who carried out the measurements.
How to halve the traffic
Measurements at the two plants in St. Brais in the Bernese Jura before and after the retrofit in July 2017 showed that a significant improvement is also achieved with a retrofit:
"The noise measurements before and after the installation of the combs showed that the noise level was reduced by 2 to 4 decibels," explains Xavier Falourd. "This is an average of 3 decibels at a wind level of over six meters per second at the height of the nacelle," the acoustics expert continues. At lower wind levels, wind turbines are barely audible.
However, even in strong winds, it is always possible to have a conversation under the turbines in a normal chatting tone.
Scientifically proven
The turbines in St. Brais already met the strict requirements of the noise protection ordinance when they were commissioned in 2009. Due to the special topographical location, however, they were still audible in the village during strong winds. However, out of consideration for the local population, the owner, the citizens' investment company ADEV Windkraft AG, reduced the output of the turbines at night.
"We are very pleased that we have finally found a solution for all parties involved and that the significant improvement could be proven with the scientific measurements of Prona SA!", explains Andreas Appenzeller, CEO of ADEV Windkraft AG. The turbines can now produce electricity around the clock without restriction and are now even quieter, especially in strong winds.
You can find out more about the Association for the Promotion of Wind Energy and its projects at. http://www.suisse-eole.ch
