Black Blade study at RWE location Eemshaven

Research project investigates the effect of black rotor blades on bird protection

Bringing operating sites into harmony with regional ecosystems is of high priority at RWE, and this is also reflected in the company’s sustainability strategy. Important goals here are the preservation of biodiversity and the protection of wildlife. This applies to conventional power plant locations as well as areas that are used for generating energy from renewable sources.

A frequent topic of discussion is how wind turbines disrupt birds’ flight paths and how improvements can be made in this area. The Black Blade pilot project in the Netherlands is looking into this issue and trying to find science-based answers. To this end, substantial and eye-catching modifications were made to seven turbines at RWE’s Westereems wind farm in Eemshaven.

One of the three rotor blades of each of those turbines was painted black and fitted with a sophisticated monitoring system comprising a camera and a motion sensor.

Westereems project site

The researchers aim to gain new insights into the birds’ flight behaviour in view of different rotor blade colours and find out whether this change leads to them flying more safely. With its large bird population and different bird species, Westereems is particularly well suited to this project.

In particular in the spring and in autumn there are many migratory birds in the area on their way further afield. Moreover, sea birds like seagulls and terns as well as land birds ranging from blackbirds and starlings to birds of prey such as buzzards and kestrels can be found there throughout the year.

More contrast = improved safety?

The study is based on the assumption that the black rotor blade leads to a higher contrast of the rotor and thus improves its visibility. This would enable the birds to see the wind turbine and fly around it.
The results of a previous study in Norway were positive. In 2021, RWE commissioned the current pilot project together with the province of Groningen.

In addition to private wind industry players, including Vattenfall and Eneco Energy, project partners also include the Dutch bird protection organisation and various state authorities.

"Black-Blade" Study | RWE

Research project aimed at observing and understanding behaviour of different bird species

The ecological research project aims to collect valid data on the behaviour of birds and to better understand the effectiveness of the black rotor blades. After the seven rotor blades were painted black in 2021, the turbines were initially observed without any additional technical components for one year. For the second stage, vibration sensors, high resolution and thermal imaging cameras and a 3D bird radar were installed at two windturbines in the Westereems wind farm, one of them with a black blade, one without. This WT-Bird® system by TNO helps to identify collisions, and to give the researchers insights into the birds’ behaviour in the proximity of the wind turbines.

The results from this research project will also be relevant to future offshore wind farms since manual measurements cannot be carried out there.

Further research aspects

In addition to the impact on native and periodically passing birds’ flight behaviour, the effects of the coloured rotor blades on flight safety and on the landscape as well as technical implications are being examined. To this end, pilots who regularly fly across the area were asked about their impressions of the black rotor blades compared to purely white ones. Their effect on the landscape in terms of how the turbines are perceived by the people in the region is also being explored.

A possible technical implication for the modified turbines is overheating of the blades on sunny days due their black colour. Thermometers have been fitted inside the blades to record these variations in temperature. Additional inspections monitor the impact on the material.

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Further research aspects
Katja Wünschel | Chief Executive Officer (CEO) Renewables Europe & Australia
Katja Wünschel | Chief Executive Officer (CEO) Renewables Europe und Australia

“As a major player in the global energy market, we are aware of the responsibility that comes with our role. For RWE, this means that we take socially relevant issues into account in our business decisions, that we also consider the consequences of our actions outside our formal area of responsibility, and that we view our business activities not only from a business perspective, but also from an ecological, social and ethical standpoint. Strict environmental legislation and licensing requirements set the framework for our operational activities in the regions where we operate. Some of our activities go beyond the obligations set out in laws and permits and this study is a good example of that.”

Katja Wünschel, Chief Executive Officer (CEO), RWE Renewables Europe & Australia GmbH

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