Shark skin varnish increases the electricity yield of wind turbines

A functional coating with microscopically small grooves, the structure of which is reminiscent of the skin of sharks, can be used to increase the efficiency of wind turbines.

Assembly of rotor blades coated with riblet paint.
Assembly of rotor blades coated with riblet paint. Source: Mertcan Bayar -

Within the EU project “Riblet4Wind”, a team of seven project partners faced the challenge of making the aerodynamics of wind turbines more efficient. One approach was to reduce air resistance. In aircraft construction, it was shown that the functional coating developed at Fraunhofer IFAM with microscopically small grooves – called riblet paint – reduces air resistance and saves fuel. The scientists took advantage of this know-how and adapted the technology to the rotor blades of a wind turbine.

Rotor blades coated with the Riblet coating

In order to assess the changes in the performance characteristics, the wind turbines were operated in their original condition for a period of twelve weeks and the corresponding performance data were determined. Subsequently, the rotor blades of one turbine were dismantled and coated with the Riblet coating. This was the first time that the automated application of Riblet paint to a large component was demonstrated.

Once the treated rotor blades had been assembled, the performance characteristics of the turbines were measured over a period of five months using a standardized procedure. Parameters such as wear and contamination were also determined.

Observable improvement in the power performance

Despite the rather old age of the turbines (approx. 20 years old), with corresponding signs of wear and stall control of the rotor blades, the coating was able to show an observable improvement in the power performance. Due to a combination of unusual weather conditions during the test period and issues with data scatter, it has not yet been possible to quantify with confidence a value for the change. The wear of the Riblet structures was negligible in the period under consideration.

Further information can be found on the “Riblet4Wind”-Website.

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