While the wind industry has rejoiced after the federal government voted earlier this week to extend the production tax credit – contributing more than $12 billion in taxpayer dollars to the renewable energy industry over the next decade – important questions remain as new studies are either wrapping up or just beginning.
Four acoustic firms in Wisconsin released a study last month that says commercial wind turbines generate “dangerous levels” of low-frequency noise. The study was led by Clean Wisconsin, an environmental advocacy organization that is “generally supportive of wind projects,” according to the 13-page report. The four acoustic firms that conducted tests in early December have worked for and against wind projects in the past, organizers say.
The results might pose an issue as wind projects move forward.
“The four investigating firms are of the opinion that enough evidence and hypotheses have been given herein to classify LFN (low-frequency noise) and infrasound as a serious issue, possibly affecting the future of the industry,” the report states.
The report highlights an ongoing debate throughout the region for setback distances. Minnesota has a minimum setback of 500 feet of turbines from occupied dwellings. The Minnesota Pollution Control Agency also states that turbines must create less than 50 decibels of noise to minimize impacts, which typically forces larger setbacks. However, the MPCA does not measure wind turbines for LFN impacts.
Critics of wind developments say those distances are inadequate. They cite countries such as Denmark, which requires setbacks of about 2,000 feet and Holland, which requires 3,280 feet. Germany’s noise-based standards range up to a full mile.
The New Era wind project in Goodhue County offered a setback of 1,500 feet. The county board responded by adopting an ordinance that required roughly half a mile. The Minnesota Public Utilities Commission eventually approved the project, conditionally, with a required setback distance of 1,626 feet.
New Era and the EcoHarmony wind project, among others, may also be facing additional hurdles in the future. The Minnesota Department of Commerce, in conjunction with the Minnesota Department of Natural Resources, posted an 81-page request for proposal on Dec. 31 that seeks to study bat fatalities within commercial wind farms in southeast Minnesota. The study is projected to cost $730,000 and last more than three years.
“This study comes at a critical juncture for planning bat conservation strategies in Minnesota,” reads the RFP. “All seven bat species found in the state are susceptible to fatality from wind turbines.”
According to the RFP, bat fatalities are projected as high as 25 per year per megawatt. Minnesota had 2,500 MW installed in 2010 – fourth-most in the U.S. – and must add an additional 4,000 MW by 2025 to meet its Renewable Portfolio Standard approved in 2007.
The final state-mandated permitting hurdle for New Era, which is 78 MW, is developing a comprehensive Avian and Bat Protection Plan; the initial attempt was rejected by the Minnesota PUC in 2012 as inadequate and a revised copy was submitted a few weeks ago.
EcoHarmony, the 280-megawatt project in Fillmore County, is located near Forestville/Mystery Cave State Park. Many turbines are sited in close proximity to bat hibernation sites. The DNR and the U.S. Fish & Wildlife Service have both expressed written concerns to that effect, dubbing it a “high risk” site for bats.