According to the AEI, with wind farm noise, as with ocean noise, “the more we learn, the more obvious it is that there is much we still do not know. And, it’s not nearly as simple as either side in this increasingly rancorous debate appears to think it is”. While the focus of the report is to digest what was learned in 2009, it also include some over-arching themes and bigger-picture context that serves as a useful introduction to those who are new to the consideration of the effects of wind farm noise on people living nearby.
The report balances sensitivity to the experiences of some wind farm neighbours who have been affected by higher than expected noise levels (including some cases of excessive sleep disruption and even abandonment of homes) within a larger context that recognises that most wind farms do not trigger noise complaints, and that many or most wind farm neighbours who can hear the turbines are not especially bothered by the noise.
To conclude, the report suggests that both the industry and local activist groups are contributing to the current polarity of denial and fear about noise impacts, and that part of the problem may be that we are facing a situation that includes some fundamental paradoxes that lead scientific studies to come to reassuring conclusions despite negative impacts on a significant minority of people within earshot.
To find out more about the issue of wind noise, Renewable Energy Magazine contacted the AEI’s Executive Director, Jim Cummings, who kindly agreed to this exclusive interview.
Interview date: April, 2010
Interviewer: Toby Price
Could you summarise in a couple of lines the results of your study into wind turbine noise?
While it appears that most wind farms generate few, if any, noise complaints (they are likely farther away from most residents), it’s also clear that a significant minority of people within a kilometre or so of wind farms find the noise to be hard to live with. Since the turbines are rated by the manufacturers as having noise levels of a bit over a hundred decibels (roughly equivalent to a leaf blower or loud car stereo), with the noise emanating from 300 or more feet high in line of sight to a large area, it isn’t especially surprising that in some conditions, they will be audible to quite some distance away.
Currently the issue of wind turbine noise relates to large wind farms. Do you have any data or comments on the impact of small wind turbines in the urban area becoming a social problem?
I have not investigated smaller backyard turbines to any great degree. However, I know than many of the innovative vertical axis designs are only made in these smaller sizes, and they’ll be less apt to create noise issues for neighbours.
What are the main impacts of wind turbine noise on people living near wind farms (health, etc.)?
The biggest negative impact is sleep disruption. This can lead to other issues (stress, irritability, depression, etc.). In some areas, daytime noise is also enough of an issue to negatively impact quality of life (enjoyment of yard and garden, etc), which also can lead to annoyance/stress/etc. Audible noise does not seem to have any direct health effects; some lower frequency sounds may be felt in the body, and while it’s unclear how or whether this can lead to health effects directly, it can be disconcerting and uncomfortable (pulsing, pressure waves are some descriptions I’ve heard). My sense is that the severe low frequency issues are rare (though real and in need of further investigation), and in most cases, health symptoms are caused by high degrees of annoyance and sleep disruption.. It is important to mention that there is a well-studied individual variability in sensitivity to noise of all kinds, and much of what we are seeing could be that when wind farms are close to dozens of homes, it is more likely that some of the neighbours will be naturally more sensitive to noise.
What would you like to see turbine manufacturers and wind farm developers doing to mitigate any acoustic impacts of wind turbines?
There would be relatively few noise issues if turbines were a half mile from homes, and virtually none if they were a mile away. (Some reports of low frequency perceptions have occurred at greater ranges, but are less common). This is not practical in many areas, but we still can consider whether plopping wind farms in and amongst homes makes sense. I do not really want to recommend what they should do, as it involves not only many practical factors, but also the willingness of landowners to live with some noise (there are many who are not that bothered). One possible approach would be to increase the cut-in speeds for turbines closer to homes: very little electricity is generated at the lower speeds, so there may be able to be a significant reduction in operating time with a minimal reduction in income (one bat study last year suggested this is possible, at least in some wind regimes).
Finally, have you been in contact with the wind industry about the issue of noise and if so, what are their general views on this matter?
I have had a few good exchanges with industry consultants and one commercial wind farm operator, but not with turbine manufacturers. There are some in the industry who recognize that the noise issue is real and must be dealt with; the preferred approach seems to be building more frank and ongoing relationships with communities, in order to minimise surprises and build goodwill toward the project. Some in the industry remain a little too convinced that all the noise complaints are convenient stand-ins for just not liking the wind farm; this may sometimes be the case, but most of the people I’ve talked to are very explicit that they do not mind seeing the towers, they just don’t want to hear them. A few in the the industry continue to say that ambient wind noise will always drown out turbines, though this is becoming more rare, thankfully. Again, this may often be the case, but in some wind/atmospheric conditions, it is quite obviously not so.
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