Hamburg (dpa) - Every day from April to October billions of insects are killed in wind turbines in Germany. That, at least, has resulted in a model calculation by the German Aerospace Center (DLR).
Overall, the losses add up to 1200 tons per year. Conservationists do not doubt the numbers of the study, but the validity: "It would be completely wrong to derive a significant threat to insect populations by wind turbines," said Lars Lachmann Nabu. In German forests alone, 400,000 tons of insects are eaten by birds each year.
The authors Franz Trieb from the DLR in Stuttgart, Thomas Gerz from the DLR in Oberpfaffenhofen and Matthias Geiger from the Leibniz Institute for Biodiversity of Animals in Bonn themselves point out that they can not say exactly how much the losses affect the entire insect population , Nor could they compare to other potential causes of declining insect density, such as increased use of pesticides, urbanization or climate change.
The three experts have determined for 2017 that the rotors of the approximately 31,000 wind turbines in Germany cover an area of approximately 158 million square meters. The average capacity utilization and the wind speed lead to the statement that about eight million cubic kilometers of air blow through the plants during the insect flying season from April to October - that is ten times the German airspace up to 2000 meters height.
One cubic kilometer of air contains about nine kilograms of insects, most of which survived an encounter with a wind turbine, the researchers explain. But five percent of them, just around 1,200 tons, fall mathematically to the wind turbines victim. That would correspond to five to six billion locusts, bees, wasps, cicadas and beetles every day of the warm season.
The German Wind Energy Association sees methodological weaknesses in the DLR study. "Wind energy generates electricity without emitting CO2 and other emissions, which are recognized as an essential threat to insect populations," said CEO Wolfram Axthelm. In Germany, wind energy alone saved CO2 emissions of 172 million tonnes last year. "Wind turbines are to be understood as a problem solver in the context of the species development of insects, not as a problem cause."
It has long been known that wind turbines can be a fatal fatality to birds and bats. But here, too, there is the problem that the scale can hardly be grasped. A statistic of the Brandenburg State Office for the Environment since 2002 lists 3,900 dead birds reported to the Office from all over Germany. Among them are many common species such as gulls, pigeons and ducks, but also rare birds of prey such as red kites and peregrine falcons. They have no chance against rotor blades that can cut through the air at the top at almost 400 kilometers per hour. According to the register, 158 white-tailed eagles alone fell victim to wind turbines in recent years, with currently around 800 breeding pairs living in Germany.
All in all, according to experts, the heavy loss in the bird world is mainly due to problems caused by intensive agriculture. According to monitoring programs, around half a billion fewer birds live in Europe than they did 40 years ago. Estimated 100,000 windmill victims per year in Germany are barely statistically significant.
However, conflicts between wind farm operators and conservationists are increasing when wind farms are to be built near lesser spotted hooves or rest areas of rare shorebirds. The protection laws have improved, but the areas for wind farms are scarcer. Conservation and environmental NGOs have a poor response to renewable energy, but they demand "a reasonable risk assessment on a case-by-case basis," Nabu said.
Model analysis of insects DLR
Opinion Bundesverband Windenergie
Bird losses at wind turbines in Germany (table)