Every year, wind turbines around the world kill millions of flying animals with their sharp blades – especially bats – which also hinders the efficient and continuous operation of the renewable energy-producing devices.
Now, researchers at Tel Aviv University (TAU) and the University of Haifa have dreamed up an innovative device designed to prevent this phenomenon.
The new development is a unique, drone-mounted technology that transmits a combination of ultrasonic signals and lights. This deters the bats and leads them to fly at a higher altitude outside the danger zone so the turbines can continue to operate efficiently and continuously.
The study was conducted under the leadership of doctoral student Yuval Werber of the department of evolutionary and environmental biology at the University of Haifa and his two supervisors – department head Prof. Nir Sapir and Prof. Yossi Yovel, head of Tel Aviv University’s Sagol School of Neuroscience and faculty member of the School of Zoology. It was also done in collaboration with the WinGo Energy Company and entrepreneur Gadi Hareli.
The article was published in the journal Remote Sensing in Ecology and Conservation under the title “Drone-mounted audio-visual deterrence of bats: implications for reducing aerial wildlife mortality by wind turbines" and was funded by a research grant from the Israeli Ministry of Energy.
The article was published in the journal Remote Sensing in Ecology and Conservation under the title “Drone-mounted audio-visual deterrence of bats: implications for reducing aerial wildlife mortality by wind turbines.” The study was funded by a research grant from the Energy Ministry.
“Wind turbines are considered a promising technology in the field of renewable energy, but their operation involves a variety of biological challenges,” Werber explained. “Today, the only solution to prevent the death of bats is to stop turbine activity at times when the bats are expected to be particularly active. But such interruptions reduce the turbines’ efficiency and the amount of energy they can produce.
“The advantage of the drone is that it is in constant motion and transmits a combination of visual and acoustic signals designed specifically for bats, warning them of danger. When signals are stationary and constant, animals tend to get used to them and eventually ignore them,” he said.
“The study, which is part of my doctoral thesis, was conducted in the Hula Valley, an area with a lot of bat activity,” Werber said. “We operated the drone at a height of 100 meters – the average height of the center of a wind turbine, and in motion along a path of about 100 meters, back and forth.”
How did the scientists reach their conclusions?
To track the bats’ activity, they used radar located on the ground, which allowed for tracking at a height of 100 meters and above and added a LIDAR (light detection and ranging) device – a laser-based tool used to detect objects at short distances, mainly in the automotive industry – for tracking at a lower height. At the same time, they made acoustic recordings of the bats in flight, using receivers placed at three different heights – one meter, 150 m. and 300 m. – and a blimp (dirigible) to elevate the receivers.
“Importantly, our study was the first in the world to combine these technologies – Radar, LIDAR and high-altitude acoustic recorders – to track bats,” Weber said.
Using a variety of monitoring methods, the researchers compared the bats’ normal activity to their activity in the presence of the drone carrying the deterrent device. The findings were unequivocal – the device succeeded in keeping the bats away. With the drone’s presence, the bats’ activity underneath it decreased by about 40% at a distance of up to about 400 meters. On the other hand, their activity increased above the drone’s altitude of 100 m. up to 800 m.
“It appears that the device is effective in repelling bats from its immediate environment – the bats sense the visual and ultrasonic signals it emits and choose to fly over it, as we had hoped,” explained Werber.
“We hypothesized that if the device is activated near a turbine, it will lead the bats to fly over the turbine and out of harm’s way,” he said. “This is an effective and easily implemented solution that is reasonably priced, with great benefit to all parties. It prevents the killing of bats and also enables the operation of the turbine and the production of green energy in a safe, continuous and efficient manner. We intend to carry out a follow-up experiment on a wind turbine site to test the efficiency of the device under these conditions.”