Large wind turbines now generating clean power without making a racket

Thanks to expertise garnered by building space telescopes powerful enough to see exoplanets, large wind turbines are now generating clean power without making a racket. European wind turbine makers were confronted with a problem: their new clean-energy turbines were efficient, effective and state-of-the-art – but they were too noisy. It turned out that ESA’s advanced Darwin planet-hunter study provided a smart answer: using the same approach that keeps multiple telescope mirrors precisely aligned to cancel out turbine vibration before it becomes noise.

Wind turbines produce two different kinds of noises. The first is the motorway-like drone from the blades. The other is ‘tonality’ – an irregular shriek from the gearbox. Tonality is even more annoying than broadband whirring noises, so governments regulate these noises very strictly. Often, the only way to keep a shrieking wind turbine from disturbing the peace of an idyllic countryside is to operate the machine at less than full power. Micromega therefore drew on their work with ESA to solve the problem quickly.

In the case of the shrieking wind turbine, the company looked back to its work on Darwin. For this to work, the mirrors of each small telescope had to be in constant alignment. To move the mirrors, Micromega developed a high-precision mechanism using magnetic bearings. This mechanism would adjust the mirrors under the exacting circumstances of space, which required that the bearings work with high precision, zero friction and at very low temperatures.

Darwin was not selected to make it into space but the space simulations developed by Micromega came in handy as they set about designing an actuator to quieten the wind turbines. The knowledge developed for space made it faster to come with an answer for the wind industry. Generating a counter-vibration – with the same size as the vibration producing the tonality, but in the opposite direction – proved to be the answer: the vibration is killed before it reaches the surface where it becomes sound.

Micromega has been working on several ESA projects activities involving magnetic-bearing suspension systems, which has put them at the top level of European industry capability for such a complex technology. The turbine manufactures appear to be happy, too. 24 large turbines retrofitted with Micromega’s technology have already been sold and many more are contracted.

Technology Transfer
Priel Manes; Cornelis Eldering