The turbines at Dutch offshore wind farms Borssele and Egmond aan Zee were stopped for four hours on Saturday 13 May, to give a large flock of migrating birds safe passage.
It is the first time that such a measure has been applied and is in line with the approach of the government and the offshore wind industry to put ecology and biodiversity at the centre of offshore wind farms, according to the Government of the Netherlands.
This first implementation of the measure is part of a pilot phase to ensure the system operates correctly and accurately.
The measure will officially take effect in the autumn of 2023 and will be continuously improved from then on.
Offshore wind farms that are under construction and future wind farms, off the Netherlands, will also participate in the measure.
Minister Rob Jetten said: “This is an international first, nowhere in the world are offshore wind farms stopped to protect birds during mass bird migration.
“We want the impact of wind farms on nature to be as small as possible and we are doing this with this measure, among other things.
“All parties involved have worked well together and set this up in a relatively short time, a great initiative that I am very proud of.”
In order to give the birds a safe passage, wind farm owners will now reduce the speed of the wind turbines to a maximum of two rotations per minute during the predicted night time peak migration.
At the end of 2022, a PhD student at the University of Amsterdam (UvA) delivered a bird migration prediction model that predicts bird migration two days in advance.
The model uses weather data and various bird radars in the North Sea. A group of migratory bird experts also predicts the chance of large bird migration two days in advance.
The two-day period gives grid operator TenneT time to guarantee the stability of the high-voltage grid. This time is also used to inform all those involved and to carefully initiate the shutdown of the turbines.
Tim van Oijen, from Vogelbescherming Nederland, said: “Twice a year, in spring and autumn, millions of birds migrate across the North Sea on some nights.
“With the growth in the number of wind farms in the North Sea, it is extremely important that we do this in the most ecologically responsible way possible with minimal impact on the North Sea.
“The temporary shutdown of the turbines during bird migration contributes to this.”
Rijkswaterstaat has developed the procedure on behalf of the Ministry of Economic Affairs and Climate Policy with, among others, wind farm owners, grid operator TenneT, the Ministry of Agriculture, Nature and Food Quality, the Bird Protection and the North Sea Foundation.