Oct 02 2014

Wind Turbine Syndrome

It looks like sustainable energy sources are going to be playing a larger role in our energy infrastructure in the future. Wind and solar are what first come to mind, but there is also hydroelectric, geothermal, and wave-generated electricity.

With the introduction of any new technology, especially on a large scale, there are bound to be some issues. Giant wind turbines are sprouting up, and this has caused some protest among people who don’t like the presence of the behemoths near their homes. Some claim that the noise from wind turbines is causing them ill health effects.

What are the real risks and benefit of wind turbines?

Energy Production

Wind turbines are rated according to their maximum power output. Typical large wind turbines are rated at 1.5 MW, or megawatts. This is their maximum energy output, which typically occurs while the wind is blowing between 30-55 mph. There are 2-3 MW models available. Below 30 mph energy production drops off dramatically.

The wind is not always blowing, however, so the average efficiency of wind turbines is 15-30%. If we take a 1.5 MW wind turbine and assume a 25% efficiency, that’s 3,285 MWh of energy production per year.

To put that into perspective, the average American home uses 10,837 KWh of energy per year, roughly 10 MWh. So one 1.5 MW wind turbine could run about 320 homes.

One main advantage of wind turbines is that they are clean sources of energy and entirely sustainable. They do not use up any limited resources and they do not generate any pollution or greenhouse gases.

Non-Health Issues

Wind turbines, however, do cause potential problems, some related to human health and others not related. The non-health issues include being an eyesore (spoiling the landscape) and their effects on animal life.

One very real concern is that large wind turbines are a potentially life-threatening hazard to flying creatures, such as birds and bats. A review of scientific studies of the number of bird deaths caused by wind turbines estimates that  140,000 and 328,000 bird deaths are caused each year.

To put this into perspective, a study published in 2013 concluded that domestic cats kill between 1.3 and 4.0 billion birds each year. There has been some criticism of the guess-work used in this study, but even if we take the most conservative number and reduce it by an order of magnitude, that would be 130 million birds each year. That’s still 1000 times greater than the number for wind turbines.

Further, an estimated 100 million birds are killed each year by flying into windows. Again, that’s three orders of magnitude more than wind turbines. Large buildings with windows are probably more of a health hazard to birds than wind turbines.

Wind turbines may, however, pose more of a threat to bats. Estimates are between 600,000 to 900,000 bat deaths per year from wind turbines.  This may be because bats evolved behaviors to follow wind currents to find food and mates, and turbines reproduce those currents, luring bats to their deaths.

As we build a larger wind turbine infrastructure, new sites can be chosen to minimize bird and bat deaths. It might also be possible to change wind turbine characteristics so they are less deadly to flying animals, or to repel bats and birds from the area of wind turbines.

Health Impacts – Wind Turbine Syndrome?

Some people who live near wind turbines report that the low frequency sounds made by the turbines cause headaches, dizziness, tinnitus, and other problems. This cluster of symptoms associated with exposure to wind turbines has been dubbed “wind turbine syndrome.”

Of course, we know from historical experience that the mere belief in a medical syndrome is not sufficient evidence to conclude that a real discrete medical entity actually exists. Belief alone is enough to drive symptoms in some individuals. Further, symptoms resulting from other causes may be falsely blamed on the syndrome that is in the popular consciousness.

What does the scientific literature have to say? A 2011 systematic review found some interesting results.

The biggest predictor of having physical symptoms that are blamed on wind turbines is annoyance at the turbines themselves. This annoyance may be due to the physical presence of the turbine itself – essentially the eyesore factor, or it may be due to the sound created by the wind turbine.

People can perceive low frequency sound if it is loud enough, over 40 decibels. This can disturb sleep, which can plausibly cause the non-specific symptoms typically blamed on wind turbine syndrome. It seems, however, that some people have symptoms because they are annoyed by the sight of the wind turbine, even when they cannot hear it.

It is also possible that even if you cannot hear the sound, the infrasound created by wind turbines can still affect the ear. This is still not clear.  Therefore, some symptoms associated with wind turbines may be due to effects on the ears, while others may be due to the annoyance factor of the constant noise.

Another study indicates that for most people traffic noise is more perceptible and annoying, although those who are especially sensitive can still pick out wind turbine noise from background traffic noise.

A very recent study is making the rounds online with headlines indicating that the study shows that wind turbines can cause hearing damage. The Daily Mail, for example, has this headline: Could living near a wind farm make you DEAF? Low frequency ‘hum’ could damage the inner ear, experts warn.

The study, however, was not a study of wind turbines. It was a study of low frequency sound and it also showed that exposure to loud infrasound could cause changes in the inner ear associated with damage – but they did not document damage itself. In the press release, however, the authors used wind turbines as an example of infrasound, and that is what the press ran with.

This study is exploratory only, showing that the effects of loud infrasound on the inner ear requires more study. No conclusions about health effects can be made, however, and again – the study did not even look specifically at wind turbines. They also used sound at 80 decibels. GE reports about its wind turbines:

The closest that a wind turbine is typically placed to a home is 300 meters or more. At that distance, a turbine will have a sound pressure level of 43 decibels. To put that in context, the average air conditioner can reach 50 decibels of noise, and most refrigerators run at around 40 decibels.

At 500 meters (0.3 miles) away, that sound pressure level drops to 38 decibels. In most places, according to Keith Longtin of GE Renewable Energy, background noise ranges from 40 to 45 decibels, meaning that a turbine’s noise would be lost amongst it. For the stillest, most rural areas, Longtin says the background noise is 30 decibels. At that level, a turbine located about a mile away wouldn’t be heard.

Studies of installed wind farms also show that most do not generate significant noise most of the time (only when wind conditions are just so). Most wind farms do not result in complaints about noise. Noise complaints from other sources, like industrial noise, are three orders of magnitude greater than from wind farms.


In each case it seems that complaints or potential problems from wind farms are exaggerated and when put into context are not very concerning. Wind turbines do represent a threat to birds, but this threat is insignificant compared to domestic cats and buildings with windows. The threat to bats is greater, and further research to reduce this threat is warranted.

Health effects may be real in some cases, but seem mostly to stem from the stress of the nuisance presented by wind turbines, both visual and auditory. There is not enough data to conclude at this time that wind turbines represent a direct threat to hearing or to overall health.

Further, the noise generated by wind turbines is minor when compared to traffic and industrial noise.

Any real problems from large wind turbines can be easily mitigated by choosing appropriate sites, far enough away from homes or high traffic areas for birds or bats. Design changes may also further mitigate potential problems, but more research is needed.

It seems to me that the benefits of wind turbines outweigh the risks, when those risks are put into a reasonable context.

27 responses so far