HS Environment | Wind turbine can act as a giant fly swatter – Scientists estimate that turbines kill a huge number of insects

When In the 1990s, wind power was installed in California, and many wind power companies encountered a puzzling problem. When the wind was strong, some of the wind turbines suddenly started to slow down.

The slowdown was significant. The rotation speed of the blades, and at the same time the electricity production, could even drop by half.

However, the phenomenon did not affect all power plants. In adjacent power plants, the speed of one slowed down and in the other it remained unchanged. When the wind weakens again, all power plants run at normal speed.

What was the matter?

Danish wind turbine manufacturer NEG Micon A/S approached researchers from the Dutch Energy Research Center who were asked to investigate the problem. Already at the beginning of the investigation, it was considered whether the problem could stem from insects. Insects fly to the blades of a wind turbine in the same way as they fly to the windshield of a car.

However, this was considered unlikely. If the blades were slowed down by the dead insects, the deceleration should have occurred gradually as the scum accumulated. In this case, however, the deceleration was sudden.

So the researchers went through ten different hypotheses. None of them explained the phenomenon, so they went back to insects. Now they turned their attention to the fact that there were a lot of dead insects below the blades. The insects stuck to the blade and dried into a ragged scab that stained the underside of the pallet dark.

When the researchers mimicked the insects’ carapace, they noticed, that the dead insects did indeed brake the blades, but the phenomenon only appeared at high wind speeds. The problem disappeared when wind power companies started cleaning the blades regularly.

Insects are a problem for wind power, but are wind turbines a problem for insects? This is hard to say because the topic is largely unexplored. Probably the only one dealing with the subject research however, gives cause for concern.

In 2018, researchers from the German Aviation Research Center estimated how much of the migrating insects fly through German wind farms, as there is data on the movements and numbers of migrating insects. According to the researchers’ modelling, around 24,000 tons of insects pass through one German wind farm every year, and an estimated five percent of them – or 1,200 tons – end up as waste in the blade of the wind power plant.

If we assume that one insect weighs a milligram, that would mean that German wind turbines would kill 1.2 trillion insects a year. There are 12 zeros in a trillion.

Crazy when looking at the numbers, you should keep in mind that this is modeling, not real-life research. Wind farms are located in very different biotopes – forests, farmland, coasts – so the selection of insects that fall victim is also different.

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Wind turbines can attract insects with their smell, sound or color.

However, what is special is that, apart from German modeling, there is practically no research on the subject – even though we are living in a time of insect disappearance. We don’t know what species wind power kills, nor do we know the extent of the problem. Famous German bat scientist Christian C. Voigt wrote last year that new studies are urgently needed on the effect of wind power on insect populations.

If the numbers in the modeling are close to reality, a five percent cut in the population of migratory insects each year would gradually begin to show up in declining populations. One of the starting points of the Germans’ modeling was to search for answers to why the number of insect species and individuals in Germany have collapsed in some places in recent years.

Wind turbines do not only threaten migratory insects. According to researchers, it is possible that wind turbines attract insects.

Many swarming insects, for example, flock to high landmarks. So it’s no wonder that swarms have been seen above wind turbines.

of Lund University in Sweden in the study the swarming of insects was monitored with the help of radar during ten consecutive late summer nights in a Swedish wind farm. The insects swarmed over the wind turbines every night, even in the dark on warm nights. The insects attracted predatory bats.

Wind turbines can also attract insects with their smell, sound or color. The smell of insects that have shriveled on the blades may attract predatory insects and carrion-eating insects. The hum emanating from wind turbines, on the other hand, can sound like the sound of swarming, which attracts more swarming insects.

At the base of the wind turbine, anyone can also see that a huge variety of insects from different taxonomic groups rest on its walls. They have apparently come there attracted by the color white, researchers have concluded.

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