A White Pine County wind farm that sells power to NV Energy has been forced to change operations after its massive turbines killed triple the number of bats allowed under an agreement with federal regulators.
The 152-megawatt Spring Valley Wind Energy project about 260 miles northeast of Las Vegas killed an estimated 566 bats in 2013, so its operator agreed to change when the windmills kick on in hopes of reducing the number of deaths.
In June, the wind farm’s 66 turbines — each standing up to 425 feet tall — were adjusted on nights with high bat activity so they would only start turning when sustained winds reach about 11 mph instead of the usual “cut-in” speed of about 7 mph.
The move was designed to reduce the number bats killed in collisions with the spinning blades because “when it gets too windy, the bats aren’t flying as much,” said Paul Podborny, a field manager with the U.S. Bureau of Land Management’s office in Ely.
Podborny is scheduled to meet next week with Spring Valley Wind representatives to review whether the new operating protocols are working. If bats continue to die in unacceptably high numbers, additional measures might include increasing the number of nights the higher cut-in speeds are used, increasing the cut-in speed even more or shutting down the turbines altogether on nights when a lot of bats are active, he said.
Matt Dallas, spokesman for San Francisco-based Pattern Energy, which owns the wind farm, said the turbine speed adjustment results in a small reduction in power output, “but we are willing to accept this in order to reduce our environmental impact.”
In an email, Pattern’s director of environmental compliance, Rene Braud, said the vast majority of the bats were Mexican free-tail bats, “a very common and abundant species” that migrates by the millions through the Spring Valley each year and is not protected under federal law.
“The project has had no impact at all on any threatened or endangered bat species,” Braud said.
To environmentalists, though, the higher-than-expected bat deaths prove what they have said all along.
Rob Mrowka, senior scientist for the Center for Biological Diversity in Nevada, put it this way: “The Spring Valley Wind project is an important component of a renewable energy portfolio placed in absolutely the wrong location.”
CAVE OF CONCERN
The $225 million project went online in August 2012 as the first utility-scale wind farm in Nevada. It features 66 turbines scattered across more than 7,600 acres of federal land at the heart of the vast Spring Valley, which runs north-south for about 110 miles between the Schell Creek and Snake mountain ranges in eastern Nevada.
The facility was designed to generate enough electricity to supply about 40,000 homes, with NV Energy as its only customer for the first 20 years of operation. It drew stiff opposition from environmentalists.
The Center for Biological Diversity and the Western Watersheds Project sued to block construction in January 2011, accusing the BLM of skirting environmental regulations to fast-track the project. Settlement talks began after a federal judge refused to stop work to allow more study of the impact on bats and sage grouse, and the resulting agreement spelled out what Pattern must do to track and curb bird and bat mortality. It also set limits on the number of deaths allowed each year: 178 birds and 169 bats.
“To me, it was a compromise to both protect the bats and allow renewable energy to still be produced,” Mrowka said. “It is highly unlikely that without the agreement and without the vigilance by the conservation groups that any action would have been taken to protect the bats.”
Biologists think as many as 3 million Mexican free-tailed bats roost in Rose Cave, about five miles from the wind farm, on their southern migration to Central America from late July through early October.
Laser beams at the cavern’s mouth track the bats as they come and go. At peak times in August as many as 2,000 bats per minute leave Rose Cave.
Research suggests bats easily can navigate around stationary wind turbines, but not even echo-location will save some of them when the blades are turning.
Each of the 262-foot towers in Spring Valley holds a rotor the diameter of a football field. When one of its three blades is pointed straight up the structure stands taller than Planet Hollywood Resort on the Strip. Though the blades appear to spin slowly, their tips can reach 170 mph, churning the air into tornado-like swirls. Even a close call can be deadly for a bird or bat because sudden changes in barometric pressure cause their insides to explode.
FEWER BIRDS THAN BATS
While bat deaths at Spring Valley Wind were well above the mitigation threshold in 2013, bird deaths were well below it. The operation reported just 40 bird fatalities last year, though one in particular garnered widespread attention. A golden eagle was killed there in February, prompting an investigation by the U.S. Fish & Wildlife Service and stoking national debate over the environmental trade-offs associated with the sort of large-scale green energy projects championed by the Obama administration in the face of climate change.
The Associated Press earlier this year documented the illegal killing of eagles around wind farms, the federal government’s reluctance to prosecute such cases and flaws in the regulatory framework.
In December, the Interior Department exempted wind farms from penalties associated with bald and golden eagle deaths for up to 30 years, provided companies obtain permits and make efforts to avoid killing protected birds.
The 30-year rule replaced an earlier version of the so-called “incidental take permit” implemented in 2009 to cover eagle deaths for up to five years. Wind energy developers argued the shorter-term permits created uncertainty that chilled investment in their projects. And since administration officials showed little appetite to penalize wind farms for killing eagles, no company ever bothered to get one of the five-year permits.
No other eagle deaths have been reported by Spring Valley Wind, but Podborny said even one more would be cause for concern and possible mitigation measures. Though bird deaths in general do not appear to be a problem at the facility, he said, “We still have to look at what species are being killed.”
Pattern Energy officials said they have been working with federal regulators since the eagle death. The company formally applied for a 30-year eagle take permit earlier this year. They expect the permitting process to last into 2015.
The Associated Press contributed to this report. Contact Henry Brean at email@example.com or 702-383-0350. Follow @RefriedBrean on Twitter.