Are wind turbines bad for you?
Do they keep people up at night? Are they annoying? Do they negatively impact health? Are they dangerous?
These questions are on Cass County residents' minds as a company prepares to bring as many as 150 wind turbines to Adams, Bethlehem, Boone and Harrison townships in the northern part of the county along with neighboring Miami County.
Sleep and health
Noise & Health, a peer-reviewed journal, published an article in 2012 about a study comparing "sleep and general health outcomes between participants living close to [industrial wind turbines] and those living further away" in two rural Maine locations.
One of the locations had 28 1.5-megawatt turbines, according to the article, while the other had "three similar turbines."
The article states questionnaires completed by participants collected information on sleep quality, daytime sleepiness and general health.
Those living within about 4,600 feet of an industrial wind turbine "had worse sleep, were sleepier during the day and had" worse mental health scores than those living farther than 4,600 feet from a turbine, the article concluded.
"Industrial wind turbine noise is a further source of environmental noise, with the potential to harm human health," the article states. "Current regulations seem to be insufficient to adequately protect the human population living close to industrial wind turbines... Further research is needed to determine at what distances risks become negligible, as well as to better estimate the portion of the population suffering from adverse effects at a given distance."
A 2011 article also from Noise & Health compared health-related quality of life of New Zealand residents living near wind turbines to those "in a demographically matched area sufficiently displaced from wind turbines." The study also relied on questionnaires.
The area in the study near the wind farm had 66 410-foot wind turbines with decibel levels ranging between 20 and 50, according to the article.
The limit called for in Cass County's wind turbine ordinance is 60 decibels.
Renewable Energy Systems, or RES, is planning to erect wind turbines about 600 feet tall in Cass and Miami counties. Brad Lila, development director for the company, said the turbines will be 3.6 to 4.2 megawatts.
"Our results suggest that utility-scale wind energy generation is not without adverse health impacts on nearby residents," the Noise & Health article states.
The World Health Organization's Night Noise Guidelines for Europe states an average of 30 to 40 decibels over one year causes effects like body movements, awakening, self-reported sleep disturbance and arousals.
WHO calls an average of over 55 decibels over one year "increasingly dangerous for public health."
Annoyance
A 2011 article in Environmental Research Letters addressing studies on wind turbine noise indicates there's "a clear association between levels of wind turbine noise" and annoyed residents.
The article goes on to conclude that "wind turbine noise is more annoying than road traffic noise at the same equivalent noise level" and speculates this could be due to wind turbines often being built in environments with low ambient noise.
"The visual intrusion of wind turbines in the environment may affect the assessment of noise annoyance," the article continues. "This is supported by the fact that the proportion annoyed by noise among residents who can see the wind turbines is significantly higher than among residents who do not see turbines at the same average noise exposure."
Falling frequencies
The Environmental Research Letters article also concludes low frequency noise from wind turbines is not greater "than road traffic noise at levels often found in urban and residential areas" and "[i]nfrasound from wind turbines is not audible at close range and even less so at distances where residents are living."
The article states support is lacking for claims that low frequency noise and infrasound from wind turbines causes serious health effects.
A Wind Turbine Health Impact Study prepared for the Massachusetts Department of Environmental Protection and Massachusetts Department of Public Health in 2012 seconds that claim.
"Available evidence shows that the infrasound levels near wind turbines cannot impact" the inner ear, the study states.
Wind turbine infrasound's effects are also insignificant in other parts of the body, according to the study.
"The measured levels of infrasound produced by modern upwind wind turbines at distances as close as [223 feet] are well below that required for non-auditory perception," like vibration in parts of the body and pressure in the chest, the study states.
Another take
Professionals in the fields of neurology, aerospace, mechanical engineering and health reviewed studies and literature on wind turbines to prepare the Massachusetts Department of Environmental Protection study.
The study states wind turbines can produce unwanted sound during operation and the sound "is perceived to increase in intensity at night." Noise is both mechanical and aerodynamic, according to the study, describing the latter as the sound made when moving turbine blades make contact with the air.
At distances greater than about 1,300 feet, the study states "sound pressure levels for modern wind turbines are less than" 40 decibels, "which is below the level associated with annoyance in the... studies reviewed."
Lila said RES is planning to build its turbines in Cass and Miami counties with setbacks from residences of at least 1,500 feet.
The study also states there's limited "evidence suggesting an association between exposure to wind turbines and annoyance" along with insufficient evidence "to determine whether there is an association between noise from wind turbines and annoyance independent of seeing a wind turbine..."
The study goes on to conclude that the information reviewed indicates "no association between noise from wind turbines and" psychological distress, mental health problems, pain, stiffness, diabetes, high blood pressure and cardiovascular disease.
Shadows, ice and gas
Wind turbine shadow flicker does not pose a risk for seizures, according to the study, which recommends shadow flicker not occur more than 30 minutes per day and no more than 30 hours per year at points of concern, like residences.
The study addresses the possibility of ice building up and falling from turbine blades as well.
"In most cases, ice falls within a distance from the turbine equal to the tower height and in any case, very seldom does the distance exceed twice the total height of the turbine," the study states.
Measures "should be taken to ensure the public is not likely to encounter such ice," according to the study.
Lila said RES's turbines will be able to perceive additional weight from ice buildup and shut down until the ice sheds.
Ice buildup on wind turbine blades is less common than it was in the past, Lila continued, adding blades have gotten more flexible over the years, preventing ice from forming as easily as on the more rigid predecessors.
Lila also responded to concerns over the turbines' effect on natural gas fields. He said such deposits lie deeper than the foundations for RES's turbines, which he added will be about 9 feet. Vibrations created by the turbines won't affect underground natural gas, Lila also said.