Bad Vibrations — Where’s the Science?

Roger Watt
Waterloo, Ontario, Canada
November, 2008


Sorry, Beach Boys, but when it comes to the big industrial-strength wind turbines that are spreading across Ontario’s landscapes, there are no “good vibrations”.

In the Source Water Protection program resulting from Ontario’s Clean Water Act of 2006, the Ministry of the Environment mandates that the local committees are to develop science-based plans to protect the sources of drinking water. Requiring a scientific basis for environmental regulations is a superb idea. MOE should have a science-based justification for its regulations on wind turbines, too.

But it seems to me that MOE’s “science” is out of date. I believe MOE’s regulations do not protect a sufficient percentage of the people who are subjected to the vibrations from wind turbines. And they focus on the frequencies to which the human ear is most sensitive, ignoring the impact that vibrations at other frequencies (particularly, low frequencies) have on other parts of the body.

I end this article with an analysis based on two reports from Japan that, I hope, could lead to better, more people-friendly regulations. I am not a wind engineer or vibro-acoustic expert, and it may well be that my simplistic treatment is flawed. I invite correction and clarification.

Why do I care?

I am a seasonal resident of Ashfield-Colborne-Wawanosh Township in Huron County, with a cottage on the shore of Lake Huron. The closest of EPCOR’s Vestas V80 Kingsbridge wind turbines are 5km inland. On quiet summer nights, I am sometimes aware of the zinging sound that tires make when cars go over the warning strips on the highway intersection 3km away. I am never aware of the wind turbines. But I have met people who live closer, and some of them are not so fortunate. That is what got me interested in this topic.

Where’s the hype?

Despite the growing body of case reports to the contrary, the wind-industry lobby continues to proclaim that there is no conclusive peer-reviewed scientific evidence that the vibrations from wind turbines have a negative impact on human health.

That is an interesting choice of words. It is the same argument that the tobacco lobby used for decades in the previous century. To quote Carl Sagan, “absence of evidence is not evidence of absence”. It is also valid to say that there is no conclusive peer-reviewed scientific evidence that wind turbines are safe.

Where’s the problem?

In 2006, I downloaded EPCOR’s 681-page Environmental Screening Report for the Kingsbridge Wind Power Project, and used its noise-estimation data [pp282-288] to graph the predicted noise at the receptor locations for wind speeds at or below 6 meters/second. I added a best-fit logarithmic curve, plus lines for the MOE 40 dB(A) threshold and two others. France has wind-turbine regulations stating that the noise may not be more than 3 dB(A) above the ambient level during the night, and not more than 5 dB(A) above the ambient level during the day. Denmark also has a special scale that uses the dB(A) weights, but involves only the low frequencies. Both of these produce setbacks from residences that are twice the distance that results from MOE’s regulations.

On pages 35 and 47 of the 2007 Ontario Municipal Board report on the hearing on the Kincardine/Enbridge wind farm, there is expert testimony that the MOE guidelines “are designed to mitigate noise impacts for about 85% of the population”, but that they “would not protect all people, as individuals perceive noise differently”.

On page 56 of the 2007 Final Report of the Noise Expert on Wind Turbine Facilities Noise Issues commissioned by MOE, the author concludes that “the MOE process has provided a balanced approach between noise impact and the need for wind farms, based on currently available scientific data”. On page 50, the report also mentions an old ISO document that lists the expected community response to wind-turbine noise that exceeds the ambient sound level: sporadic complaints at 5 dB, widespread complaints at 10 dB, threats of community action at 15 dB, and vigourous community action at 20 dB.

There are reports indicating that rural areas remote from well-travelled roads can have night-time ambient noise levels as low as 25 dB(A) on quiet summer nights. However, MOE states that the acceptable level for a rural area at wind speeds of 6 m/s or less is 40 dB(A) or the minimum hourly ambient level, whichever is HIGHER. There are other reports that the noise from wind turbines on quiet summer nights can be much greater and carry much farther than predicted by the noise-estimating software used by the wind industry today.

MOE’s regulations are creating situations in which the expected community response will range from widespread complaint to vigourous action. It should come as no surprise that 24 citizen-action groups from 14 counties recently united to form Wind Concerns Ontario.

Where’s the science?

Two recent scientific works from Japan seem relevant. The first verifies that people’s ability to detect vibration follows a normal distribution, for all frequencies from 25 Hz to 18,000 Hz. The second lists the dB levels that can be detected by various percentages of the population at each frequency:

Perhaps we can use these to investigate some people-friendly regulations. Consider, for example, this simple four-step approach.

  1. From the second report, we can take the dB values for the mid-point frequencies that are used in computing dB(A) values, and derive the lowest dB(A) levels that various percentages of the population can detect.
       percent:  1   5  10  20  30  40  50  60  70  80  90  95  99
       dB(A):    7  12  13  16  18  20  21  23  25  27  30  33  38
  2. An expert at a public-forum ACW Council meeting stated that passage through walls and open windows will reduce the exterior noise by 10 dB(A). So, adding 10 to the above should give us the lowest outside dB(A) that can be detected inside.
       percent:  1   5  10  20  30  40  50  60  70  80  90  95  99
       dB(A):   22  27  28  31  33  35  36  38  40  42  45  48  53
  3. Various reports state that an increase of 5 dB(A) above the ambient level will begin to yield complaints from the community. So, by adding another 5 to the above, we get the dB(A) at which we can expect various percentages of the population to complain.
       percent:  1   5  10  20  30  40  50  60  70  80  90  95  99
       dB(A):   27  32  33  36  38  40  41  43  45  47  50  53  58
  4. By reversing the top row, we get the percentage of the population that should find the dB(A) acceptable … ie, without complaint.
       percent: 99  95  90  80  70  60  50  40  30  20  10   5   1
       dB(A):   27  32  33  36  38  40  41  43  45  47  50  53  58

This suggests that MOE’s 40 dB(A) regulations meet the needs of only 60% of Ontario’s rural population. If MOE were to adopt regulations based on noise not exceeding any receptor point’s lowest pre-existing ambient background level by more than 3 dB(A) by night and 5 dB(A) by day, that could meet the needs of 95% or more of the population.

What’s the conclusion?

The resolution of this must fall to our elected representatives. For what percentage of the population is it acceptable to sacrifice health and well-being in order to meet green-energy goals for wind turbines?

To quote Gordon Miller, Environmental Commissioner of Ontario, in his “State of the Great Lakes” keynote address at the 2008 It All Ends Up In The Lake conference, now is the time to make waves. If the concerned citizens in your community don’t yet have an action group, form one, and unite with Wind Concerns Ontario.


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