Wind turbines kill tens of thousands of flying animals – especially bats and birds – each year.  It’s a growing problem that worries conservationists intent on fostering renewable energy sources but also protecting wildlife. Traditional means of deterrence, including the posting of acoustic devices that emit sounds to startle flying animals, aren’t always effective.  Over time, the creatures simply become habituated to their presence.  Limiting the rotation speed of the turbines, while partially effective, also reduces their efficiency – and ultimately, their profitability – a non-starter with power companies.  How can this perennial dilemma – conservation vs. economic benefit – be resolved? With drones, say some researchers.

A recent study conducted in Israel and published in the journal Remote Sensing and Ecology in Conservation found that drones in constant movement above and below a wind turbine caused bat mortality to decline dramatically – between 40%-50% in the period tested.  The researchers used RADAR and LIDAR to track bat movements during the test period to determine precisely how they reacted to the drones and their pulsating sounds of alarm.  Compared to the control group,  a large percentage of  bats flew over or under the turbine to escape being drawn into its vortex.

Deterring bat mortality – with drones or another device – has only recently become a top research priority.   For years, scientists believed their main animal of concern was birds, but it turns out that bats, which are nocturnal and lack good eyesight, are far more vulnerable.  The erection of wind turbines has added to the mortality problem because bats often mistake the structures for tall trees.  Without a powerful deterrent, hungry bats are highly likely to pursue moths and other insects straight into the whirring blades of a turbine, experts say.

Bats also suffer from a somewhat creepy reputation that makes them less attractive as a focus of policy concern.  In fact, bats are an important part of the ecosystem. Bats pollinate plants and flowers, disperse seeds and eat thousands of insects every night, reducing crop damage and pesticide use by an estimated $3.7 billion annually.  And unlike birds, they live long lives and reproduce slowly, which means bat deaths on a large scale – 880,000 per year, due to wind turbines, according to some estimates – pose a growing risk to the survival of the species.

The Biden administration is considering the use of drones to deter bat fatalities as part of its strategy to increase U.S. reliance on wind power – not just on land, but also at sea.   The Department of Energy just awarded a $1.6 million grant to EPRI, an energy research and development nonprofit group, to study what kind of environmental conditions are likely to attract bat activity in possible offshore wind areas in the Pacific Ocean. EPRI’s team plans to deploy acoustic sound devices on boats, buoys, and drones to determine which of the devices is most effective in detecting and deterring bat flight patterns.

Interest among state governments and local power companies is also growing.  After a 2020 study at Duke University found an even larger (80%) reduction in bat mortality due to sound deterrents, Duke Energy decided to mount a stationary sound device atop all of its 255 wind turbines at Los Vientos in the Rio Grande Valley in Texas – the first such installation in the continental United States.  So far, no company has deployed drones for this purpose but with further successful tests, it’s only a matter of time, industry analysts say.

Previous Drone News: