Black Blade study at RWE location Eemshaven

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

Research scope
Approach
Findings & Results

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 project in the Netherlands investigated this issue and sought 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 aimed to gain new insights into the birds’ flight behaviour in view of different rotor blade colours and examined whether this change leads to them flying more safely. With its large bird population and different bird species, Westereems was 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 assumed that painting a rotor blade black might increase the contrast of the rotor and thereby improve its visibility, enabling birds to better perceive the turbines and potentially avoid collisions. Initial studies in Norway had yielded positive results. Building on this, in 2021, RWE launched the pilot project at Westereems 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.

A wind turbine turns under a clear blue sky with some clouds and flying birds in the background.

Research Approach and Observations

The ecological research project collected data on bird behaviour to better understand the effectiveness of black rotor blades. After painting the seven black blades in 2021, the turbines were observed for one year without any additional technical components. Subsequently, advanced monitoring systems, including vibration sensors, high-resolution and thermal imaging cameras, and a 3D bird radar, were installed on two turbines within the wind farm—one with a black blade and one without. Developed by TNO, this WT-Bird® system helped identify collisions and provided insights into bird behaviour near the turbines.

The results from this research also held relevance for future offshore wind farms, where manual measurements could not be conducted.

Findings and Follow-up Research

By early 2025, the project concluded that painting one rotor blade black did not significantly reduce bird strikes. Researchers suspected this was due to the black blade not contrasting sufficiently with the busy background. However, studies from other locations, including Smøla in Norway and South Africa, had shown positive results using either black blades or a combination of black and red banding. To draw definitive conclusions, further research was deemed necessary to understand the underlying mechanisms - such as whether birds perceived the turbines at all - and to explore alternative patterns or colours that might increase visibility and contrast.

The study also underlined the importance of combining ongoing studies across different locations to comprehensively evaluate effects under varied conditions.

Additional aspects of the study

Beyond bird behaviour, the project also examined the effects of coloured rotor blades on flight safety, landscape aesthetics, and technical implications. Regional pilots who frequently flew over the area were surveyed about their perceptions of the black rotor blades compared to standard white ones. The visual impact on the landscape and how turbines were perceived by local communities were also evaluated.

On the technical side, the black blades were monitored for potential overheating on sunny days. Thermometers installed inside the blades recorded temperature variations, while additional inspections were conducted to assess material impact.

Collaboration and Partners

The Black Blade study was completed in June 2025 and involved a partnership between public and private stakeholders, including RWE, Vattenfall, Eneco Energy, Statkraft, Pure Energie, the Dutch bird protection organisation Vogelbescherming, and authorities such as the Ministry of EZK/LNV, Rijkswaterstaat, and several provincial governments. More information about the project and its findings can be found on the website of the Province of Groningen (dutch only).

A person with blonde hair is wearing a pink blazer and a white blouse. The background is bright and blurred, portrait of Katja Wünschel.
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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