Intelligent Energy

Nevada's first wind farm heads to 'the bat cave'

Nevada's first wind farm heads to 'the bat cave'

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As construction begins on Nevada's first wind farm, will radar systems help prevent "barotrauma," i.e., what happens to a bat that gets too close to a turbine?

Nevada has broken ground on it's first wind farm despite its proximity to Rose Guano Cave, a popular haunt for about a million Brazilian free-tailed bats.

Environmental groups and Native American tribes have been trying to halt the project, filing a lawsuit in January. Their injunction attempt failed in April, and last week, Pattern Energy announced that they've begun construction on Spring Valley wind farm. Come next winter, the San Francisco-based company plans to install 66 wind turbines on the 8,565-acre site. Rose Guano Cave lies four miles away.

Research has found that bat deaths on wind farms don’t typically result from striking turbine blades but by "barotrauma." This occurs when the small mammals’ lungs can't cope with sudden air pressure changes when the blades whir past. The deaths typically happen at night and during the summer when insects buzz around turbines the most. During their migration each August and September, around 1 million Brazilian free-tailed bats (also called Mexican free-tailed bats) roost in the cave.

The groups, who are appealing the U.S. District Court's decision, object to the Bureau of Land Management's fast-tracked handling of the farm's approval process. Approved in October, the proposed 150-megawatt project completed an environmental assessment but lacked a more rigorous Environmental Impact Statement.

Rob Mrowka, an ecologist with the Center for Biological Diversity, said in a statement initially announcing the lawsuit:

Renewable energy is nationally and globally important for addressing the growing threats from climate change, but renewable projects must be properly located with careful consideration of natural values — not only those of the site, but also those of the surrounding area.

The best ways to avoid negative impacts with renewable energy projects are to carry out a thorough environmental review and site them carefully. Unfortunately, in this case the BLM did neither.

The environmental assessment did, however, lay out how the developers intended to address their wildlife issue—which also concerns golden eagles, pygmy rabbits, sage grouse, and other bat species. Following similar precautions taken at their Gulf Wind farm (right) to protect birds, Pattern Energy plans to install radar systems that would track birds and bats as they approach the farm. Acoustic devices would also monitor the bats when they move in and out of the cave.

MERLIN radar units, developed by DeTect, have a range up to 4.6 miles. Vertically, they can track bird and bat flights up to heights of 0.86 miles. According to the assessment, the farm's two units could signal to some or all of the turbines to shut down when necessary. For a closer look at what is flapping nearby, a VESPER radar system would measure the wingbeat frequencies of birds, bats, and even bugs flying through its beam. This could potentially provide valuable insect data that might help decrease bat deaths.

If all goes according to plan, the outcome would hopefully play out as it does in the animation below.

In February, the Fish & Wildlife Service drafted voluntary guidelines for wind farms proposed for federal lands. Wind farms, of course, aren't alone in the world of renewable projects meeting wildlife habitat. The lives of desert tortoises and some proposed solar farms in the Southwest have also overlapped, fueling lawsuits as well. Recently the Western Watershed Project, a group also involved in the Spring Valley suit, temporarily halted fence construction on BrightSource Energy's Ivanpah Project in southern California.

In a report released last winter, The Wilderness Society suggests a few locations on federal lands where large solar farms could exist with minimal effect on what's living around them.

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Images: National Park Service, CDC, and DeTect

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Melissa Mahony

Contributing Editor

Contributing Editor Melissa Mahony has written for Scientific American Mind, Audubon Magazine, Plenty Magazine and LiveScience. Formerly, she was an editor at Wildlife Conservation magazine. She holds degrees from Boston College and New York University's Science, Health, and Environmental Reporting Program. She is based in New York. Follow her on Twitter. Disclosure