New research: wind turbine noise heard as far as 3.5 km
Cruel joke: Ontario’s 550 metre setback and government/industry notion that it is impossible to hear turbines past 1500 metres
March 3, 2020
New research from Australia has been published in the Journal of Sound and Vibration which shows that wind turbine noise goes a lot farther than the wind power lobby and turbine manufacturers would have you believe.
A lot farther.
Ontario’s setback, supposed to protect people from sleep disturbance and other effects of environmental noise pollution, is just 550 metres. This was suggested to the McGuinty government by the wind power lobby, after the Ontario government proposed a setback of 1 km.
The Australian research demonstrates that indoor low-frequency tone was detected 20 percent of the time at distances up to 2.4 km; the noise dissipated somewhat but was still perceived 16% of the time at a distance of 3.5 km. The authors note that complaints made to the South Australian Environmental Protection Agency came from people living as far away as 8 km!
Here is an excerpt from “Prevalence of wind farm amplitude modulation at long-range residential locations”:
Overall, it is important to determine how often AM is present at residential locations near a wind farm. In this view, Australian researchers from the Flinders University: Dr. Kristy Hansen, Phuc Nguyen, Dr. Branko Zajamšek, Prof. Peter Catcheside, in collaboration with Prof. Colin Hansen at The University of Adelaide studied the prevalence and characteristics of wind farm AM of a certain windfarm in Australia. Their goal was to determine how often AM occurred at various distances from the wind farm and to assess the suitability of the IOA ‘reference method’ for detecting low-frequency AM of a tone that is generated by wind turbines. Their research work is currently published in Journal of Sound and Vibration.
Their approach involved outdoor measurements for a total of 64 days at 9 different residences located between 1 and 9 km from the nearest wind turbine of a South Australian wind farm, which at the time of measurements was made up of 37 operational turbines, each with a rated power of 3 MW. The motivation for their analysis was to investigate the prevalence of a low-frequency ‘thumping’ or ‘rumbling’ noise that had been mentioned in complaints from residents.
… In summary, the study investigated the prevalence and characteristics of wind farm AM at 9 different residences located near a South Australian wind farm. Their work showed that, despite the number of AM events being recorded to reduce with distance, audible indoor AM still occurred for 16% of the time at a distance of 3.5 km. At night-time, audible AM occurred indoors at residences located as far as 3.5 km from the wind farm for up to 22% of the time. In a statement to Advances in Engineering, Dr. Kristy Hansen pointed out that the adopted approach was successful, although more research was needed to quantify the annoyance and sleep disturbance potential of the recorded type of tonal AM.
In Ontario, wind turbines are approved using a noise assessment protocol (developed by acoustics consultants often contracted to do work for wind power developers), using a computer-generated predictive model of the noise. As well, Renewable Energy Approvals require post-operational audits, many of which are incomplete, or have not been submitted at all.
The environment ministry has held the belief that it is impossible to hear turbine noise at 1500 metres and callers to the ministry District Offices or Spills Line are told their complaint is not accepted, and their files are closed, Wind Concerns Ontario has discovered in reviews of Incident Reports provided under Freedom of Information requests. Wind Concerns ONtario has so far tracked 5,200 formal records of complaints held by the government. How many would there be if people had not been told their complaint was impossible?
See a summary of the research here: Summary of Prevalence of wind farm amplitude modulation-2019
The actual paper is available here for a fee.
P.S. Thanks to U.S. acoustics expert Robert Rand for publicizing the existence of this research.