Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dangerous flight into the wind farm

08.07.2016

Wind turbines attract bats. They seem to appear particularly appealing to female noctule bats in early summer. In a pilot study, researchers of the German Leibniz Institute for Zoo and Wildlife Research in Berlin noticed this when they tracked the flight paths of noctule bats, Nyctalus noctula, using the latest GPS tracking devices . The bats managed to take even seasoned experts by surprise.

The motive behind the study is the conflict between the exploitation of wind energy and the conservation of the protected bats. The German so-called ‘Energiewende’, the full transition from conventional to renewable energy sources, causes a steady increase in the number of wind power facilities (wind farms).


Graphic.

C. Voigt, IZW


Common noctule bat with band for identification.

Foto: Manuel Röleke

This expansion of wind power production throughout Germany is also likely to drastically increase the total number of bat fatalities at wind turbines. There appears to be therefore a conflict between the development of renewable energy sources and the conservation of endangered and legally protected bats; a so-called green-green dilemma.

According to expert estimates, about 250,000 of bats sailing through the night sky are currently dying at wind turbines every year as long as turbines are operated without mitigation measures. The cause of bat death is either a direct collision with the rotor blades of turbines or a barotrauma caused by abrupt air pressure changes in the tailwind vortices associated with the moving rotor blades.

These abrupt air pressure changes shred the inner organs of bats and kill them instantly. Seventy percent of the bats slain by German wind farms are migrating bat species. Noctule bats (Nyctalus noctula) are among these migrating bat species. They are also among the largest bats flying in the night skies of Europe.

How do bats interact with wind farm facilities? Where do bats prefer to hunt their favorite insect prey? What distances do bats fly during the hunt for prey? How high do they fly anyway? To answer these questions, the research group working with Christian Voigt fitted adult noctule bats with miniaturised GPS data loggers. As a test area, the researchers selected a patch of forest in Brandenburg, east Germany. Cultivated land and several wind parks surround this forest patch.

The result: In the early days of summer, female bats seem to be virtually fixated on the giant wind farms. The majority of female bats even crossed the wind parks.

Christian Voigt suspects the following: "One explanation considers the fact that bats make their homes in trees. In early summer, having just finished raising their pups, the female bats take off looking for new homes and hunting grounds. Conceivably, the bats mistake the wind farm constructions for large dead trees, ideal for serving as bat homes. Our American colleagues have suspected this to be the case for North American bat species already. By contrast, male bats generally avoided the wind park facilities and continued to commute between their headquarters and hunting grounds without much variation. These male bats had no reason to venture out. They had already established their quarters earlier in the year."

In general, the bats left their quarters about 30 minutes after sunset. Female bats flew longer and expanded their hunting grounds to a much larger area than the male bats. The researchers were surprised by the long distances the bats flew on their hunts. On average, female bats spent 1.5 hours in the air and covered almost 30 kilometers during their hunt. The average hunting time for males was only 1.0 hour. In this time, they covered only 15 kilometers.

A few individual bats flew up to 250 meters high. However, the hunting excursions of 95 percent of the bats covered only heights between 0 and 140 meters above ground. This is risky business for the bats because in most wind farms, the turbine rotors turn at heights between 70 and 130 meters!

The researchers also learnt that male bats prefer ‘bio-prey’. Their favorite hunting grounds were above or near organically grown crops. Male bats spent only 21 percent of their flight time above fields with conventionally grown crops. Females were a little less finicky but avoided forest areas. Both male and females frequently hunted near linear structures such as hedgerows or alleys.

The results are further evidence in favor of the idea that environmental goals and conversation goals are in principle compatible with each other. When searching for real estate for future wind parks, operators should exclude certain environments from consideration. These include meadows and pastures, cultivated areas with organic crops and areas close to rivers and lakes or areas with linear landscape elements. Before considering the installation of a wind farm, bat detector devices can indicate whether bats use the area as hunting ground. Such bat detectors listen in on the echolocation calls of bats and automatically record them. "According to legislation, the investor and operator who plan to establish some wind farm facility must test for the presence of bats. Alas, imposed regulations remain largely unheeded!" mentions Christian Voigt.

Small changes in the operation of existing wind farms would be sufficient to minimise bat fatalities and defuse the renewable energy – bat conservation conflict. Bats only rarely fly at temperatures below 10 °C and wind speeds above eight meters per second. This wind speed is close to the minimum where the net energy production of a wind turbine starts. Operating the turbines only at wind speeds above eight meters per second would cause less than one percent loss in terms of electricity generated, a minute loss for the operator. The required technology for adjusting the operation of wind turbines in this manner already exists and is readily available. It would therefore be no big deal to support bat conservation in addition to providing green energy. Why does it not happen more frequently? Christian Voigt ventures a guess: "Wind farms already carry the green stamp of renewable energy production. As a consequence, the operators feel that they made a sufficient contribution to environmental protection. However, it should be the objective of an intelligent ‘Energiewende’

to work sustainably in all areas. This should include both measures to alleviate climate change and the conservation of biological diversity. Climate protection and the conservation of species are compatible. It is quite simple to avoid sites with large bat populations and to institute the respective shutdown times in the operations of wind farms. This would drastically reduce bat fatalities around wind farms."

Bats are listed as protected species in Germany as well as in the entire EU. They are the only mammals capable of true active flight, and they play a very useful role in the environment. Bats in Europe live exclusively on insects. Aside from devouring heaps of menacing mosquitos, they also make short shrift of the legions of crunchy beetles and juicy caterpillars which would otherwise make a meal out of every ear of corn and most vegetables in fields and gardens. "Bats are veritable service providers for ecosystems. Farmers should appreciate their contribution. They have to use far less insecticide as long as bats hunt for insects above their fields."

Every killed bat is sorely missed in the population because bats reproduce slowly. Not only local populations but also those of migrating bats shrink in size if there are too many bat fatalities around wind farms. The fatality rates are particularly devastating for bat species on their way from northeast Europe, where they reproduce, to southern and western Europe via Germany, where they hibernate during the winter months.

Contact

Leibniz Institute for Zoo and Wildlife Research (IZW)
in the Forschungsverbund Berlin e. V.
Alfred-Kowalke-Str. 17
10315 Berlin
Germany

Christian Voigt
Tel.: +49-30-5168-517
voigt@izw-berlin.de

Steven Seet (Press)
Tel.: +49 30 5168-125
seet@izw-berlin.de

Saskia Donath | Forschungsverbund Berlin e.V.
Further information:
http://www.fv-berlin.de

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>