Science

Drone-mounted "bat shield" could help prevent wind turbine collisions

Drone-mounted "bat shield" could help prevent wind turbine collisions
Ultrasound and light emitters were attached to the plastic struts of the drone's landing gear
Ultrasound and light emitters were attached to the plastic struts of the drone's landing gear
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Ultrasound and light emitters were attached to the plastic struts of the drone's landing gear
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Ultrasound and light emitters were attached to the plastic struts of the drone's landing gear

Wind energy is often thought of as "clean" but, in fact, the technology has the blood of thousands – if not millions – of bats on its hands. That's not only because bats can fly into the giant wind turbine blades and die, but because the turbines create a low-pressure field which causes the bats' internal organs to explode when they pass through it. A new drone-mounted system shows promise in rerouting some bats above the turbine blades and away from danger.

While wind turbines kill about 140,000-500,000 birds a year according to the Audubon Society, the death toll for bats is much higher. That's because as the turbine blades spin, they create a five-to-10-kilopascal drop in pressure behind them, according to Scientific American.

When bats fly through this low-pressure zone, their capillaries expand rapidly and the animals die from internal hemorrhaging. Birds tend to have stronger capillaries, so they can withstand the pressure drop more easily.

To combat this negative side effect of a promising energy-producing technology, researchers have experimented with blade-mounted whistles, as well as using ultrasonic waves to keep bats away from the deadly turbines. But the whistle process could prove costly, and the ultrasonic wave devices tested are stationary, which tends to make the system ineffective over time as animals habituate to it.

Researchers at Tel Aviv University and the University of Haifa have come up with a system that could address both issues: brightly flashing lights and ultrasonic pulses delivered from drones that fly in front of the turbines. Flashing lights at bats might seem an odd choice as a deterrent if you have been led to believe that bats are blind, but the creatures do in fact have highly sensitive eyes that can pick up on visual clues.

To see if the light/sound combo would in fact deter bats, the researchers launched their drone in Israel's Hula Valley, which is noted for significant bat activity. For the bulk of the test, the drone flew at a height of 100 meters (about 328 feet), which is the average height of a turbine. Then, it flew back and forth in front of the turbines on a path about 100 meters wide while flashing its lights and playing its sounds.

Next, using a combination of ground-based RADAR, laser-based LIDAR tracking devices, and acoustic receivers, they tracked the bats' flight patterns. The drone was successful in rerouting about 40 percent of the bats above the turbines. During the test (seen in the video below), there was no wind turbine present, but the researchers plan to test the drone again at a turbine as the next phase of the study.

The drone that could save bats from the terror of wind turbine blades

"We hypothesize 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," said Yossi Yovel, head of Tel Aviv University's Sagol School of Neuroscience. "This is an effective and easily-implemented solution that is reasonably priced, with great benefit to all parties: on the one hand, it prevents the killing of bats, and on the other hand, it enables the operation of the turbine and the production of green energy in a safe, continuous and efficient manner."

The researchers' work has been published in the journal, Remote Sensing in Ecology and Conservation.

Source: Tel Aviv University via Phys.org

8 comments
8 comments
aksdad
If only there were an incredibly efficient way to generate electricity on a large scale safely and reliably at any time day or night with no pollution or carbon dioxide emissions from a fuel source as abundant as the oceans with enough to last a billion years so we could dispense with the intermittent, unreliable power of the bird-and-bat-choppers. Hmmm...
christopher
@aksdad If only there were a way to stop autocratic kleptocracies from murdering their neighbors with the impunity they get form hiding behind weapons built from electricity generation byproducts...
Charyus
@Christoffer, right on the spot!

We need to embrace that technology worldwide and asap.
Rick O
Maybe an alternative would be to add something to the blades themselves that generate light/sound? Low power LED strips might be enough to warn them away, and would look pretty cool at night too, lol
White Rabbit
The goal of the project is laudable, but its potential value is impossible to assess without more information.
Turbine blades tend to be about 52 meters long which means their sweep is 104 meters plus the diameter of the nacelle. The flight path of the drone is said to be 100 meters wide. Does this imply that each turbine needs a dedicated drone? Note the use of the singular article in the first sentence of the last paragraph...
"'We hypothesize 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,' said Yossi Yovel, head of Tel Aviv University's Sagol School of Neuroscience."
With battery TBR (Time Between Recharge) in the 45 minute range the system will require a full-time attendant just to do battery swaps for every 3 or 4 drones. Even if each one can detour bats around multiple turbines the cost of the labour required will be huge.
We need more data!
Nelson Hyde Chick
Rick O, that makes too much sense to be implimented.
DaveWesely
At this point, the researchers are trying to figure out what would work to warn the bats away from danger. Once that is figured out, they can tackle the implementation. For instance, instead of the drones being battery powered, perhaps they could be tethered to the front of the nacelle with power cables.
And @aksdad, a nuclear plant takes about 7 years to build. An equivalent wind farm can be built in 6 months. Land based wind turbines produce electricity with an LCOE of $30/MWH, while nuclear is about $120/MWH.
ljaques
@white rabbit Many drones have automatic recharging bases, so this would take care of your costly personnel problem.
@aksdad Two Bit DaVinci on YT did a solar requirement calc for the world: (3 farms of 207x207 miles, pulling 8hr shifts.)
The actual fix is SMRs, wave and tidal energy collection, offshore wind, ubiquitous solar, and much more effective use of power by humans.