Can things be as bad as they are painted?
Image copyright - Simon Watson
The fatal attraction of wind turbines
A long term research programme in the Communications Division has focused on the impact of humans on biological sonar systems found in nature - specifically those of bats and marine mammals. Recent work has included an investigation into bat interaction with wind turbines from an acoustic perspective.
Part of this study was undertaken by PhD student Chloe Long whose work was the first study to empirically assess insect attraction to wind turbines. She looked at the relationship between a wind turbine’s colour and the number of insects it attracts finding that the most commonly used turbine colours, white and pale grey, are also top of the colour charts for insects, only beaten by yellow for attractiveness.
If insects are drawn to turbines, their predators, bats and birds, will inevitably follow. The Communications Division is currently assessing the scale of the problem and how the bat populations in areas close to wind turbines are affected. There is nothing else in a bat’s environment which moves in the same way – i.e. which rotates in one plane of motion at a relatively high angular velocity. Bats’ sonar mechanisms are not designed to detect that kind of target and they have not developed adaptive behaviours to cope with the challenge. This can and does prove fatal, though the extent of the problem is not yet known. The bat conservation trust in the UK has developed a position statement on the problem:
see http://www.bats.org.uk/pages/wind_turbines.html for details.
Can bats ‘see’ turbines?
Because bats rely on the transmission of sound to interpret their environment (echolocation), investigation is underway into how bat echolocation pulses might interact with moving turbine rotor blades. Two papers on this work are currently in press and due for publication shortly.
One of these papers details an equation that can be used to rate wind turbine rotors in terms of how detectable they are to an approaching bat (i.e. how likely a bat’s echolocation pulse is to be intercepted by a blade and reflected as the rotor operates). In theory this can be applied to any make of turbine or used to design a more ‘bat-detectable’ rotor.
The second paper examines how the information contained in bat echolocation pulses might be modified after reflection from an operational rotor, and what this might mean for a bat. Many bat species utilise the shift in frequency that occurs in an echo reflected from a moving object (known as ‘Doppler shift’) to assess the movement and speed of their prey (such as moths).
One of our key findings in this study was that the frequency shift of echoes reflected from a turbine rotor operating under low wind speed conditions may be sufficient to prevent the bat indentifying the target correctly, i.e. some species may not be able to perceive the true movement of the turbine blades.
To read a report on Chloe Long’s work by Matt Walker, the BBC’s Earth News editor, click here.
University contacts:
For further information about the bat projects
Dr James Flint - Head of Communications – j.a.flint@lboro.ac.uk
For information about wind turbine research
Prof Simon Watson – Head of Energy – s.j.watson@lboro.ac.uk
Media enquiries – please contact our Public Relations Team - publicrelations@lboro.ac.uk