HOLY RESEARCH BATMAN! Scientists Help Solve Issues With Bats and Wind Power

Bats fly to the top of the “issues” list when it comes to wind power. New research, however, helps to solve this wildlife fatality issue.

Ed Arnett, PhD, is a wildlife biologist/conservation scientist and leading expert on bats and wind power. Dr. Arnett is the co-director of programs at Austin-TX, based Bat Conservation International (BCI).

Bat fatalities decreased because of Arnett’s team and what they learned from the new research.

The bat fatality problem was identified in 2003 when researchers found an extraordinary amount of bat kills at the Mountaineer facility in West Virginia, and at a site in Tennessee. Fatalities are widespread and worldwide. "The fatalities at Mountaineer were higher than had ever been reported, 48/turbine," Arnett says.

Arnett, BCI, the American Wind Energy Association, U.S. Fish and Wildlife Service, and the National Renewable Energy Lab partnered to initiate the Bats and Wind Energy Cooperative (BWEC) shortly thereafter and revisited the Mountaineer site in 2004. (You can go here

One of the most interesting things Arnett found was that bats are killed the most on nights with low wind speed; so researchers reduced the amount of operating hours on low end periods.

Ultimately, when turbines spin less that means less power and less money.

But there is more to wind power than earning money. Some firms want to be good citizens, especially in a green industry.

Arnett defends his position. "The wind doesn't always blow strong," Arnett says. "The bats are more active at low wind speeds but the turbine blades rotate at full RPM even at these low wind speeds, and the bats are killed during these periods. If the blades aren't turning  at all during very low or no wind periods bats don't get killed."
 

Arnett and his team of researchers hypothesized that they could reduce fatalities substantially by reducing the amount of the operating hours. This hypothesis worked but it took time. Arnett says it took a few years to find a company willing to host this kind of experiment. In the summer of 2008 Iberdrola Renewables offered up the Cassleman Wind Power Project in Pennsylvania.
 

Since the summer of 2008 Arnett and his team analyzed the data and found that bat fatalities were dramatically reduced. The data showed that when you change the cut in speed of the turbine (the wind speed at which turbine-produced electricity enters the power grid) from the normal operating speed, and leave the turbines in a feathered state (blades pitched parallel to the wind that do not spin) until the wind reaches that new cut in, you reduce the amount of operating hours.

These particular turbines at Casselman are 3.5 mps (meters per second) cut in speed, and Arnett's team tested changes to 5 and 6.5 mps. Arnett's experiment showed reduced bat fatalities between 53%-87% on any given night. The average on any given night was 73% reduced fatalities.
 

"By doing this we've demonstrated substantial reductions and with only relatively small power losses, about 0.3 to 1% of the total annual
output," Arnett says. Were these power losses okay with Iberdrola? Arnett says they were and this is substantiated by a press release from Iberdrola.

Iberdrola (BIBE.MC) is currently the world's leading provider of wind power with more than 8,000 MW of wind power in operation globally. "We were proud to offer our Casselman site for this experiment and  provide funding for it. We fully support the efforts of the BWEC," Andrew Linehan, director of permitting for Iberdrola says in the release. "We believe  this is the responsible thing to do and recognize there is an impact on bats that requires scientific study. We're committed to hosting this effort which represents a new area of investigation for the wind industry. The new information generated by the Casselman project is useful in improving many techniques for
reducing wildlife risk at those wind power sites where there are significant impacts to bats."

A full copy of the Iberdrola study can be found here [pdf]: Effectiveness of Changing Wind Turbine Cut-in Speed to Reduce 
Bat Fatalities at Wind Facilities