Safety
Operation of any utility-scale energy conversion system presents safety hazards. Wind turbines do not consume fuel or produce pollution during normal operation, but still have hazards associated with their construction, operation and maintenance.
With the installation of industrial sized wind turbines numbering in the thousands, there have been at least 40 fatalities of workers due to the construction, operation, and maintenance of wind turbines, and other injuries and deaths attributed to the wind power life cycle.Most worker deaths involve falls or becoming caught in machinery while performing maintenance inside turbine housings.
If a turbine’s brake fails, the turbine can spin freely until it disintegrates or catches fire. Often turbine fires cannot be extinguished because of the height, and are left to burn themselves out. In the process, they generate toxic fumes and can scatter flaming debris over a wide area, starting secondary fires below. Several turbine-ignited fires have burned hundreds of acres of vegetation each, and one burned 800 square kilometres (200,000 acres) of Australian National Park.
During winter ice may form on turbine blades and subsequently be thrown off during operation. This is a potential safety hazard, and has led to localised shut-downs of turbines. Modern turbines can detect ice formation, and shut down.
Electronic controllers and safety sub-systems monitor many different aspects of the turbine, generator, tower, and environment to determine if the turbine is operating in a safe manner within prescribed limits. These systems can temporarily shut down the turbine due to high wind, ice, electrical load imbalance, vibration, and other problems. Recurring or significant problems cause a system lockout and notify an engineer for inspection and repair. In addition, most systems include multiple passive safety systems that stop operation even if the electronic controller fails.
In his book Wind Energy Comes of Age, Paul Gipe estimated that the mortality rate for wind power from 1980–1994 was 0.4 deaths per terawatt-hour. Paul Gipe’s estimate as of end 2000 was 0.15 deaths per TWh, a decline attributed to greater total cumulative generation.
Aesthetics
Newer wind farms have larger, more widely spaced turbines, and have a less cluttered appearance than older installations. Wind farms are often built on land that has already been impacted by land clearing and they coexist easily with other land uses (e.g. grazing, crops). They have a smaller footprint than other forms of energy generation such as coal and gas plants. Wind farms may be close to scenic or otherwise undeveloped areas, and aesthetic issues are important for onshore and near-shore locations.
Aesthetic issues are subjective and some people find wind farms pleasant and optimistic, or symbols of energy independence and local prosperity. While some tourism officials predict wind farms will damage tourism, some wind farms have themselves become tourist attractions, with several having visitor centers at ground level or even observation decks atop turbine towers.
Residents near turbines may complain of “shadow flicker” on nearby residences caused by rotating turbine blades, when the sun passes behind the turbine. This can easily be avoided by locating the wind farm to avoid unacceptable shadow flicker, or by turning the turbine off for the few minutes of the day when the sun is at the angle that causes flicker.
Wind towers require aircraft warning lights, which may create light pollution. Complaints about these lights have caused the FAA to consider allowing fewer lights per turbine in certain areas.
Noise
Modern wind turbines produce significantly less noise than older designs. Turbine designers work to minimise noise, as noise reflects lost energy and output. Noise levels at nearby residences may be managed through the siting of turbines, the approvals process for wind farms, and operational management of the wind farm.
Renewable UK, a wind energy trade organization, has said that the noise measured 350 m from a wind farm is less than that from normal road traffic or in an office; some physicians and acoustic engineers have reported problems from wind turbine noise, including sleep deprivation, headaches, dizziness, anxiety, and vertigo.
Nina Pierpont, a New York pediatrician and wife of an anti-wind energy activist, states that noise can be an important disadvantage of wind turbines, especially when building the wind turbines very close to urban environments. The controversy around Pierpont’s work centers around her statements made in a self-published, non-peer-reviewed book that ultra-low frequency sounds affect human health, which are based on a very small sample of self-selected subjects with no control group for comparison. She asserts that wind turbines affect the mood of people and may cause physiological problems such as insomnia, headaches, tinnitus, vertigo and nausea.
In December 2006, a Texas jury denied a noise pollution suit against FPL Energy, after the company demonstrated that noise readings were not excessive. The highest reading was 44 decibels, which was characterized as about the same level as a 16 km/h wind. The nearest residence among the plaintiffs was 1,700 feet from one of the turbines. More recent lawsuits have been brought in Missouri, Pennsylvania, and Maine.
In the Canadian Province of Ontario, the Ministry of the Environment created noise guidelines to limit wind turbine noise levels 30 metres away from a dwelling or campsite to 40 dB. These regulations also set a minimum distance of 550 metres for a group of up to five relatively quiet 102 dB turbines within a 3-kilometre radius, rising to 1,500 metres for a group of 11 to 25 noisier 106-107 dB turbines. Larger facilities and noisier turbines would require a noise study.
In a 2009 report about “Rural Wind Farms”, a Standing Committee of the Parliament of New South Wales, Australia, recommended a minimum setback of two kilometres between wind turbines and neighbouring houses (which can be waived by the affected neighbour) as a precautionary approach. In July 2010, Australia’s National Health and Medical Research Council reported that “there is no published scientific evidence to support adverse effects of wind turbines on health”.
A 2008 guest editorial in Environmental Health Perspectives published by the National Institute of Environmental Health Sciences, the U.S. National Institutes of Health, stated: “Even seemingly clean sources of energy can have implications on human health. Wind energy will undoubtedly create noise, which increases stress, which in turn increases the risk of cardiovascular disease and cancer.”
The Japanese Environment Ministry will begin a “major study into the influence of sounds of wind turbines on people’s health” in April 2010, because “people living near wind power facilities are increasingly complaining of health problems”. They plan a four-year examination of all 1,517 wind turbines in the country.
A 2007 report by the U.S. National Research Council noted that noise produced by wind turbines is generally not a major concern for humans beyond a half-mile or so. Low-frequency vibration and its effects on humans are not well understood and sensitivity to such vibration resulting from wind-turbine noise is highly variable among humans. There are opposing views on this subject, and more research needs to be done on the effects of low-frequency noise on humans.
Research by Stefan Oerlemans for the University of Twente and the Dutch National Aerospace Laboratory suggests that noise from existing wind turbines may be reducible by up to half by adding “saw teeth” to the trailing edges of the blades, although research is not complete.
2009 review
A 2009 expert panel review, described as being the most comprehensive to date, delved into the possible adverse health effects of those living close to wind turbines. Their report findings concluded that wind turbines do not directly make people ill.
The 85-page study was sponsored by the Canadian Wind Energy Association and American Wind Energy Association. The academic and medical experts who conducted the study stated that they reached their conclusions independent of their sponsors. “We were not told to find anything,” said panel expert David Colby, a public health officer in Chatham-Kent and a Professor of Medicine at the University of Western Ontario. “It was completely open ended.”
The study did allow that some people could experience stress or irritation caused by the swishing sounds wind turbines produce. “A small minority of those exposed report annoyance and stress associated with noise perception…” [however] “Annoyance is not a disease.” The study group pointed out that similar irritations are produced by local and highway vehicles, as well as from industrial operations and aircraft.
The report found, amongst other things, that:
- “Wind Turbine Syndrome” symptoms are the same as those seen in the general population due to stresses of daily life. They include headaches, insomnia, anxiety, dizziness, etc…
- low frequency and very low-frequency “infrasound” produced by wind turbines are the same as those produced by vehicular traffic and home appliances, even by the beating of people’s hearts. Such ‘infrasounds’ are not special and convey no risk factors;
- Colby stated that evidence of harm was so minuscule that the wind associations were unable to initiate other independent collinear studies by government agencies. It was not surprising that their requests met with complete blanks on the need to examine the issues further;
- one study member noted: “You can’t control the amount of cars going by and wind turbine noise is generally quieter than highway noise”;
- the power of suggestion, as conveyed by news media coverage of perceived ‘wind-turbine sickness’, might have triggered “anticipatory fear” in those close to turbine installations.
The study panel members included: Robert Dobie, a doctor and clinical professor at the University of Texas, Geoff Leventhall, a noise vibration and acoustics expert in the United Kingdom, Bo Sondergaard, with Danish Electronics Light and Acoustics, Michael Seilo, a professor of audiology at Western Washington University, and Robert McCunney, a biological engineering scientist at the Massachusetts Institute of Technology. McCunney contested statements that infrasounds from wind turbines could create vibrations causing ill health: “It doesn’t really have much credence, at least based on the literature out there” he stated.
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