Resource Documents — latest additions
Documents presented here are not the product of nor are they necessarily endorsed by National Wind Watch. These resource documents are provided to assist anyone wishing to research the issue of industrial wind power and the impacts of its development. The information should be evaluated by each reader to come to their own conclusions about the many areas of debate.
Author: Hanning, Christopher
Recent evidence confirms and strengthens my 2010 conclusions that wind turbine noise at the levels permitted by Australian regulations has unacceptable adverse effects on sleep and health.
The NHMRC statement on wind turbine noise and human health fails in its duty to “build a healthy Australia” and to protect the public health by; reversing the burden of proof, applying an inappropriately high burden of proof and failing to properly apply the precautionary principle. They have, instead, applied the “reactionary principle” (Kriebel 2007), which is clearly not in the public interest. Had they correctly applied the precautionary principle, then, even using their present analysis, they would have called for an immediate moratorium on the construction of new wind turbines within at least 1.5km of residences and immediate reductions in noise emissions from existing wind turbines sited within 1.5km of residences. Had they applied a reasonable burden of proof, they would have called for a construction moratorium and noise emission reductions for turbines sited within 10km of residences. In addition, they would have mandated research by independent experts with relevant expertise in acoustics, sleep medicine and other relevant clinical disciplines, funded by the wind industry, as an urgent matter for the protection of public health.
The “nocebo” hypothesis is falsified at many levels. There is overwhelming evidence that the adverse health effects complained of by wind turbine neighbours and reported in the many publications cited in this and my 2010 submission are caused by the noise emissions of wind turbines.
The Australian regulations on wind turbine noise are not fit for purpose. They take no account of relevant earlier research, excessive amplitude modulation and low frequency sound emissions and were formulated to favour the industry rather than the public health.
In November 2012, I was privileged to make a lengthy, detailed written submission to the Australian Senate Inquiry into Excessive Noise from Wind Farms and subsequently gave oral evidence on 13th November.
I concluded that: “… there is compelling evidence that wind turbine noise can and does disturb sleep and impair the health of those living too close and that current guidance is inadequate protection.”
I see no useful purpose in restating my previous evidence as it is in the public domain and available to the Committee. I shall, therefore, restrict my evidence to three principal areas:
1. New evidence since 2012
2. Commentary on the recent NHMRC statement on wind turbine noise and human health
3. Commentary on the “nocebo” hypothesis
Fourthly, I shall comment on the wind industry and its supporters as “Producers of Doubt”.
Christopher Hanning, BSc, MB, BS, MRCS, LRCP, FRCA, MD
Author: Hansen, Colin
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]).
- 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”.
- 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.
- 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
- 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
Author: Bahtiarian, Michael; and Beaudry, Allan
Noise Control Engineering, LLC (NCE) was retained by Senie & Associates P.C. to evaluate the acoustic impact at the home of Neil and Betsy Andersen at 211 Blacksmith Shop Road, East Falmouth, Massachusetts. The goal of the evaluation was to determine if the three nearby wind turbines were detectable within the interior of the home. These wind turbines are all Vestas, model V82 at 1.65 megawatts. Two wind turbines are owned by the Town of Falmouth; known as “Wind #1” and “Wind #2”. The third turbine is privately owned by Notus Clean Energy and referred to as the “Notus” turbine. Wind #1 is the closest to the Andersen home at a nominal distance of 1,385 feet. The other two wind turbines are more than double that distance.
Soon after the first wind turbine was operational, complaints were filed by the Andersens and other neighbors. In the following years, evaluations of audible sound were performed by various organizations including NCE, consultants for the Town, consultants for Notus, and even the Massachusetts Department of Environmental Protection (MADEP). Various results were reported with some evaluations showing compliance and some showing non-compliance.
The study reported herein differed in a number of ways from previous evaluations performed by NCE and others. The major difference is that the primary measurements reported here is infrasound. Briefly, infrasound is sound pressure levels with frequency below 20 hertz which is generally considered an inaudible frequency range. Another difference is that measurements were taken both inside and outside the home. All previous tests were performed at exterior locations due to the fact that State regulations and local ordinance were only applicable at outdoor locations.
The methods used herein allowed for the collection of infrasonic sound pressure levels within the inside of the Andersen residence. Inspection of this data shows that there is a readily identifiable acoustic signature that is attributable to the Wind #1 Turbine, and to slightly lessor extent the Wind #2 turbine both inside and outside the Andersen home. These results are similar to results from other international researchers with references given in the report.
Based on our experience, NCE can unequivocally state that the infrasonic signature captured inside the Andersen residence with the wind turbines operational is 100% attributable to one or both of the Town’s Wind Turbines. To put the conclusions more commonly, this study finds that the wind turbine(s) produce acoustic emissions which are “acoustically trespassing” into the Andersen home.
February 27, 2015
Noise Control Engineering, Billerica, Mass.
Author: Van Renterghem, Timothy; Bockstael, Annelies; De Weirt, Valentine; and Botteldooren, Dick
Annoyance, recognition and detection of noise from a single wind turbine were studied by means of a two-stage listening experiment with 50 participants with normal hearing abilities. In-situ recordings made at close distance from a 1.8-MW wind turbine operating at 22 rpm were mixed with road traffic noise, and processed to simulate indoor sound pressure levels at LAeq 40 dBA. In a first part, where people were unaware of the true purpose of the experiment, samples were played during a quiet leisure activity. Under these conditions, pure wind turbine noise gave very similar annoyance ratings as unmixed highway noise at the same equivalent level, while annoyance by local road traffic noise was significantly higher. In a second experiment, listeners were asked to identify the sample containing wind turbine noise in a paired comparison test. The detection limit of wind turbine noise in presence of highway noise was estimated to be as low as a signal-to-noise ratio of −23 dBA. When mixed with local road traffic, such a detection limit could not be determined. These findings support that noticing the sound could be an important aspect of wind turbine noise annoyance at the low equivalent levels typically observed indoors in practice. Participants that easily recognized wind-turbine(–like) sounds could detect wind turbine noise better when submersed in road traffic noise. Recognition of wind turbine sounds is also linked to higher annoyance. Awareness of the source is therefore a relevant aspect of wind turbine noise perception which is consistent with previous research.
Timothy Van Renterghem, Annelies Bockstael, Valentine De Weirt, Dick Botteldooren
Department of Information Technology, Ghent University, Gent, Belgium
Science of the Total Environment 456–457 (2013) 333–345