DTE says turbine bird, bat deaths not out of the ordinary

HURON COUNTY — A recent study of 183 DTE Energy wind turbines found that bird and bat deaths per megawatt is just above average compared to other wind parks in the Midwest.

“We’re not the highest, but we’re just above average (in bird deaths),” said Dennis Buda, operations manager for Thumb Wind Parks at DTE.

“We are almost in the middle of all of the bat fatality rates, and that is on a per megawatt install basis in all of the parks,” Buda said in a recent presentation to the Huron County Planning Commission.

The wind parks in the post-construction wildlife study were Sigel, Echo, McKinley, Brookfield and Minden, which is in Sanilac County.

Birds died at a rate of about 4 birds per megawatt, and the rate of bat deaths was 6 per megawatt, DTE Wind Development Manager Matthew Wagner told the Tribune.

Each turbine produces a maximum of 1.6 megawatts, while the maximum capacity factor is 32 to 35 percent, Wagner said.

“We’re within the rates recorded at other Midwestern and Eastern wind energy facilities,” Buda said. “There were no correlation found between the habitat variables, such as distance to wooded areas, or water sources. … No species that were protected under federal or Michigan endangered species were found.”

DTE contracts with a third party to do the wildlife studies, Buda said.

Huron County Commissioner John Nugent sits on the planning commission. He cited an article in Scientific American that stated delaying the cut-in speed of the turbines (the speed at which the turbine connects to the grid) could prevent bat deaths.

Buda said the current speed is 3.5 meters per second (mps), and will be 4 to 4.5 mps with new echo adaptive software recently purchased from General Electric.

Nugent said bat mortality could be reduced, according to the article, if the blades are feathered at 5 to 6.5 mps.

Buda said he wasn’t sure how those numbers were achieved, and that “Everything is a balance.”

“If we are operating in an area, temperature, time of year where activity can be/is high for bats,” Buda told the Tribune, “Then this software will delay the start of those turbines to allow the bats to adapt and find the blades and stay away from them.”

Buda cited a study in his presentation to the planners by the American Wind Wildlife Institute, which found the following U.S. bird fatality statistics:

• The biggest culprits in bird fatalities are cats, who kill 1.4 to 3.7 billion birds per year.
• Buildings and windows kill 988 million birds annually.
• Agricultural tiling practices cause the death of 1-2 million birds annually.
• Wind energy is responsible for 214,000 to 368,000 bird deaths per year.

Less than 0.1 percent of all bird deaths are from wind turbines, said Cindy Hecht, DTE spokesperson.

Buda told the planners that the most significant threat faced by populations of North American migrant birds are habitat destruction and climate change caused by fossil fuels.

“DTE is very concerned. We’re working close with the (U.S. Fish and Wildlife) Service (USFWS), and we’re trying to strike that balance,” Buda said. “The more we do, the more we learn, and the better off we’re all going to be.”

DTE is currently working with its corporate biologist, USFWS and its third-party contractor on a presence/absence study where microphones were placed throughout the wind parks to determine the specific kinds of birds or bats that are in the area.