Volume 36
Issue 3
Bat deterrent devices are placed strategically on wind turbines in an effort to repel
bats from the blades.
Photo: Cris Hein / BCI.

This summer, while many of us were traveling for summer vacation or visiting friends and family, quiet tests were underway on three North American wind farms that could be a huge boon to bats.

BCI worked with NRG Systems to test out the companys latest bat deterrent device on 48 wind turbines in the U.S. and Canada. Six devices per turbinepointed up, down, forward, sideways and backwardspulsed out ultrasonic beams designed to repel bats from the wide sweep of the turbines rotors.

And if all goes well, the deterrent devices could be on the market for wide-scale wind industry use by the end of 2017. It will round out more than a decade of effort by BCI, deterrent manufacturers and the wind industry to arrive at a solution.

Beginning in June, BCI Wind Program Director Cris Hein, together with Brogan Morton, product manager for NRG Systems, and three separate wind energy partners, began gathering data on how the new units performed atop a range of wind turbine models. A main goal was to determine whether the ultrasonic deterrents could be used at any wind facility in the U.S. and Canada, regardless of the turbines in use at a given site.

Previous designs just werent robust enough to justify a full marketing ramp-up, Morton said. As well as being plagued by overheating and damage by water leaking into the casings, they also werent reducing bat mortality as much as had been hoped. Earlier field tests showed a roughly 30 percent decrease in bat mortality; the goal is to reduce bat mortality by at least 50 percent.

Testing is expensive, running into the hundreds of thousands of dollars per test. In addition to funding by the wind industry partners, the current round of testing was made possible by a 2015 grant from the U.S. Department of Energy.

People have to have confidence that the units will work, that theyre worth investing in, Morton said.

Demonstrating effectiveness is also intensively time consuming, involving daily hunts on the ground below for bat carcasses to compare turbines with and without the deterrents. Improvements to the new deterrent designs include a longer operational life, around 10 years; the ability to remotely control and monitor the units; and an increased ultrasonic broadcast range that reaches to the edges of the rotors tips under most conditions. High humidity, for instance, reduces the distance ultrasonic waves can travel.

Hein and Michael Schirmacher, BCIs wind energy program manager, have been instrumental in helping NRG key in on the range of ultrasonic frequencies that keep most bats away, between 20 and 60 kilohertz, as well as placement on the turbines themselves, Morton noted.

The tests are also looking at how well the deterrents work at lower wind speeds. One effective strategy to reduce bat collisions at turbines has been to curtail, or shut turbines down, during low wind days. But as wind technology improves in its ability to generate power from ever lower wind speeds, curtailment for wildlife can begin to add up in reduced energy production.
This is a solvable issue, Hein said. Were testing strategies that will not only protect bats, but allow for full operation of wind turbines and maximize green energy. We can have the best of both worlds.

We all know that with the climate challenges we face, renewable energy is a good path, but we cant ignore the local effects on wildlife, Morton added. But we dont have to choose between the two. Technology can break the tension between those things.