Black blades can reduce the number of bird collisions by 70 percent, a Norwegian study has shown. But will Dutch birds follow the same behaviour and could dark-coloured wind turbine blades be accepted by the Dutch public? A new study in Eemshaven aims to find the answers.
Seven wind turbines in Dutch Eemshaven will have one of the turbine blades painted black. The purpose is to investigate if the method can contribute to reducing the risk of birds getting injured by colliding with the turbine blades. The study has already started and is expected to run until the end of 2024.
This year a baseline measurement will be done. Next year, the blades will be painted and for two years, the turbines be monitored whether that has an impact on the number of bird collisions. In addition, aviation safety and the impact of the painted blades on the landscape will be examined.
Taking previous research to the Netherlands
A study financed by Vattenfall and a group of Norwegian partners on the island of Smøla in Norway has already examined the effect of black wind turbine blades. That study showed that painting one blade resulted in 70 percent fewer collisions.
“That has to do with the way birds perceive the moving rotor of a wind turbine,” says Jesper Kyed Larsen, Environmental Expert at Vattenfall. “When a bird comes close to the rotating blades, the three individual blades can ‘merge’ into a smear and birds may no longer perceive it an object to avoid. One black blade interrupts the pattern, making the blending of the blades into a single image less likely.”
However, the Netherlands is home to other bird species and the landscape is very different from that in Norway, as is the meteorological conditions. Jesper Kyed Larsen again:
“We are continuously looking at ways to reduce the impact of wind turbines on the environment, and we are therefore very excited to be part of this study at Eemshaven to better understand the potentials of the black blade measure in a Dutch context. If we could find other ways of reducing collision risk to birds than temporarily stopping the turbines, and losing renewable energy production, that would of course be better for everybody.”
Effects on the landscape
One point of discussion in the Norwegian study was that black blades are more conspicuous, not only to birds but to humans too. The question was whether the surrounding area would be affected by the visual effect.
“Norway’s west coast is not known for its blue skies and sunshine. On the contrary, it often has grey and rainy weather or days with mixed cover of often fast-moving clouds giving a very patchy illumination of the landscape and turbines within it. The black blades therefore hardly stood out in the landscape, no more than the grey blades in any case,” says Bjarke Laubek, who is also an Environmental Expert at Vattenfall. “The people living in the area didn’t seem to be too bothered by it, and the black-painted blades were therefore allowed to stay until the end of their lifespan instead of just for the duration of the research project. In the Netherlands, we have clear blue skies more often than in Norway. The light setting on the turbines is therefore different, but it is still difficult to estimate how noticeable the black blades will be in a Dutch landscape. “
Effects on the blades
It will also be important to gain more knowledge about the practical and financial aspects of the black blade measure in a Dutch context. Will the black paint affect the durability and as a result the maintenance needs for the blades? The study at Eemshaven will be considering this as well.
Vattenfall is participating in the black turbine blade pilot project together with a number of energy companies and Dutch public authorities such as Groningen Province. The windfarm in Eemshaven is owned by RWE.
Cranes and geese avoided Danish wind turbines
In 2020, Vattenfall completed and extensive research project into the behaviour of birds in the vicinity of wind turbines in North Jutland in Denmark. Jesper Kyed Larsen: “The research showed that the birds studied were much better at avoiding colliding the wind turbines than expected. Well above 99 percent of the pink-footed geese and cranes flying in the area were able to avoid the turbine blades.”
By Clemens van Gessel