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Submission to the Senate Select Committee on Wind Turbines: Hansen  

Author:  | Australia, Health

Thank you for the invitation to provide a submission to this enquiry. My submission is relevant to items (c), (d), (e) and (f) in the terms of reference, as these relate to my areas of expertise which include acoustics, vibration, and noise measurement and assessment. As you will be aware, the recent NHMRC study concluded that “there is currently no consistent evidence that wind farms cause adverse health effects in humans”. However, there are also no studies that show that wind farm noise does NOT cause adverse health effects in humans, but this seems to have been forgotten.

The NHMRC information paper on which the NHMRC conclusion was based is flawed for a number of reasons which were pointed out to (but ignored by) the NHMRC. Some of these reasons are listed below. More details are provided in my review of the NHMRC draft information paper (included as an appendix to this document [also here]).

  1. The criteria used in the information paper to decide which research papers were worthy of being included in the study are obviously flawed as papers by many well-known scientists published in internationally recognised journals were rejected, yet one report by a resident near the Waterloo wind farm who has had no research training was included. Even the included papers were labelled as “poor in quality”, which then leads to the inevitable conclusion that there is “no consistent evidence that wind farms cause health effects in humans”.
  2. The assumption that wind farm noise is like any other noise of the same A-weighted decibel level is flawed. The authors of the information paper used this to justify why in the absence of high-quality studies on wind farm noise, they could use “studies on the health effects of similar emissions from other sources to inform its consideration of the direct evidence and in forming its overall conclusions”. Our measurements of wind farm noise in and around residences in the vicinity of wind farms indicate that wind farm noise is very different to other environmental noise such as traffic noise at the same A-weighted noise level (which I assume is the measure used by the information paper authors to define a “similar emission”) The difference lies in the low-frequency dominance of the noise produced in residences by wind farms, which is not quantified very well by the A-weighting metric. The other problem is that wind farm noise is highly variable and in many cases it varies at a regular rate so it sounds like “pulsing” or “thumping”, much like the bass sound from a party people may be having next door. Unfortunately this does not stop at midnight but may continue all through the night for several nights in a row before there is any respite. It is well known that this type of noise is annoying. It is also well known that some people annoyed by noise have difficulty sleeping and that sleep deprivation can lead to health effects, yet the authors of the information paper could find no evidence to support these well known facts.
  3. The assumption that the A-weighting measure can be directly related to the effect that noise has on people. This assumption showed no appreciation of the fact that the A-weighted noise level typically reported is a level that has been averaged over a period of time, usually between 10 and 15 minutes. Wind farm noise varies considerably over short periods of time and the peak levels can be much greater than levels averaged over 10 to 15 minutes.
    Select Committee on Wind Turbines Submission 50
  4. The assumption that A-weighted levels recommended by the World Health Organisation to avoid sleep disturbance, which were derived from traffic noise studies in urban areas would also apply to wind farm noise in rural areas. This ignores the fact that background noise levels in rural areas (especially in Australia) are well below background noise levels in urban areas and wind farm noise has entirely different characteristics to traffic noise, which makes it more intrusive and annoying.

Wind farm noise has the potential to be an even more serious problem in Australia than in Europe or the USA, because in Australia, rural environments in which wind farms exist are inherently very quiet. Current regulations in Australia allow for 40 dBA of noise to be produced at the nearest rural residence as a result of a wind farm. Although there is a 35 dBA limit for rural townships, this does not apply to farmers’ residences outside of the township zone. The 40 dBA allowable level is not an upper limit that cannot be exceeded by the wind farm. Rather, it is based on severe averaging. First, the data used are LA90 levels (the A-weighted level exceeded 90% of the time). This assumes that wind farm noise does not fluctuate, clearly an incorrect assumption, so the 90% of the time that the wind farm noise is above the allowed level is ignored. Next, the LA90 data are averaged for 10 minutes and each 10-minute average data point is plotted on a graph of LA90 vs wind speed at turbine hub height. Then a line of best fit (polynomial regression) is drawn through the data and compared to the 40 dBA recommended level. So there can be many data points, each of which represents a 10-minute average, that are characterised by noise levels above 40 dBA. In conclusion, the 40 dBA limit for wind farm noise is not sufficiently low to ensure that rural residents will not suffer from sleep disturbance. Also the 40 dBA limit does not account for the increased annoyance of a noise dominated by low frequencies.

One problem with current compliance assessment procedures using unattended monitoring is that it is easy to state that any levels that were measured above the allowed limit may not have been due to the wind farm – could be wind in the trees or insects or vehicles or animals. Thus any compliance measurements must be based on the recording of time series data that can be replayed in the lab for periods when the noise level exceeded the allowed level, so that extraneous noise sources can be ruled out. Measurements between 11pm and 5am are preferred as that is when people are trying to sleep and when extraneous noise sources are not likely to be a problem. In fact it would be better if any measurements of existing background noise levels before the construction of the wind farm were made between 11pm and 5am, rather than averaging over day and night, as it is the night time when the wind farm noise is most intrusive.

There is also a considerable amount of controversy surrounding whether or not infrasound can be adversely affecting the health of some people directly, making them suffer symptoms similar to sea- sickness. There are many case studies of people who have seasickness like symptoms in their homes near a wind farm, but who become symptom free when they leave their homes for a few days. The skeptics among us like to say that these people have symptoms even when the wind farm is turned off for a short time. However, I wonder how many people suffering from sea-sickness when on a boat, feel 100% well immediately they step on to shore. It is also interesting that a well-known Australian acoustician has found that wind farm generated infrasound exists even when the turbine blades are turned off and stationary (paper by Les Huson to be published in the Proceedings of Wind Turbine Noise April, 2015, Glasgow). This is a result of wind blowing past the tower and blades, causing them to vibrate at resonance and radiate infrasound.

Accusing people adversely affected by wind farm noise to be suffering from the “nocebo” effect, as you will no doubt see on many web sites and blogs, is selling them short, but not surprising if one appreciates the billions of dollars at risk for the wind farm industry. However, I am appalled by the level of emotion and personal attacks on people who express concern about wind farm adverse health effects, which are exhibited on some blogs, especially by university researchers who ought to have an open mind. The fact is that the jury is still out on the effects of infrasound on some people – no-one knows for sure, although there is plenty of anecdotal evidence that wind farms make some people feel ill. This is why the NHMRC has stated that they will soon be calling for research grant applications to address the lack of evidence. However, the $500,000 they have set aside will not be sufficient to fund a comprehensive interdisciplinary study and certainly not the sort of study that will satisfy all the barely possible criteria set by the authors of the NHMRC information paper (see https://www.nhmrc.gov.au/_files_nhmrc/publications/attachments/eh57a_information_paper.pdf).

An interesting report concerning a study funded by the wind farm company, Pacific Hydro, which demonstrates the effects of inaudible noise on some residents near the Cape Bridgewater wind farm is available from http://www.pacifichydro.com.au/english/our-communities/communities/cape- bridgewater-acoustic-study-report/?language=en. If infrasound is a problem, it will have ramifications for the recommended set back distance for wind farms. It will also require research to identify the mechanisms responsible for the noise and to devise ways to ameliorate it once its mechanism is properly understood. Even if the problem is the low-frequency thumping noise (which I suspect is at least an important part of the problem), its generating mechanism will need to be understood and again means for its amelioration devised. However, while the wind farm industry and its vocal supporters continue to claim that any perceived noise problem is “all in residents’ heads”, much needed research will continue to be unfunded and wind farms will continue to ruin the lives of a significant percentage of rural families. The exact percentage is hard to quantify but for some wind farms it could be as high as 10 to 20% or more.

One method that has been used in the past to obtain social survey results that hide the true story of the problems experienced by people living near wind farms is to study a cohort of people living within 10 km of a wind farm and then compare them with another cohort not living near a wind farm. The area surrounding a wind farm at a distance between 5 and 10 km is much greater than the area between a distance of 1 km and 5 km (no-one has to live closer than 1 km if they are not a host) and there will be at least 4 times as many people in the distance between 5 km and 10 km (for a uniform population density) where the problems are very much smaller. Therefore a study that concludes that only a small proportion of people living within 10 km of a wind farm are annoyed or highly annoyed or suffer adverse health effects is really a skewed study unless it takes into account the distance of each residence from the nearest turbine.

The undue influence that a large multi-billion dollar industry, such as the wind farm industry, can exert, is evidenced in the sacking of Professor Henrik Møller, a highly regarded acoustics professor from Aalborg University in Denmark, who has published, in high-quality international scientific journals, many peer reviewed papers on wind turbine noise and the effects of low-frequency noise on people. The publication of his results led to the Danish turbine manufacturer, Vestas making number of complaints to the university about his work, as his results were not in the best interests of the wind farm industry. Prior to his sacking, Prof Moller developed a low-frequency noise meter that people could take into their houses to detect levels of low-frequency noise for comparison with the Danish standard of 20 dB. However, the project making use of this meter has been discontinued, as Prof Moller’s colleagues are worried about losing their jobs if they continue with this work. One would hope that the situation does not deteriorate to this level in Australia. However, no researcher has the resources to engage in a court case should the wind farm industry decide to sue for damages.

Colin H Hansen, Emeritus Professor, University of Adelaide
February 24, 2015

Submission to the Senate Select Committee on Wind Turbines

This article is the work of the author(s) indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.

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