Resource Documents: Australia (145 items)
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Prevalence of wind farm amplitude modulation at long-range residential locations
Author: Hansen, Kristy; Nguyen, Phuc; Zajamšek, Branko; Catcheside, Peter; and Hansen, Colin
Abstract:
The presence of amplitude modulation (AM) in wind farm noise has been shown to result in increased annoyance. Therefore, it is important to determine how often this characteristic is present at residential locations near a wind farm. This study investigates the prevalence and characteristics of wind farm AM at 9 different residences located near a South Australian wind farm that has been the subject of complaints from local residents. It is shown that an audible indoor low-frequency tone was amplitude modulated at the blade-pass frequency for 20% of the time up to a distance of 2.4 km. The audible AM occurred for a similar percentage of time between wind farm percentage power capacities of 40% and 85%, indicating that it is important that AM analysis is not restricted to high power output conditions only. Although the number of AM events is shown to reduce with distance, audible indoor AM still occurred for 16% of the time at a distance of 3.5 km. At distances of 7.6 and 8.8 km, audible AM was only detected on one occasion. 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.
Kristy L. Hansen, Phuc Nguyen, College of Science and Engineering, Flinders University, Tonsley, Australia
Branko Zajamšek, Peter Catcheside, College of Medicine, Flinders University, Bedford Park, Australia
Colin H. Hansen, School of Mechanical Engineering, The University of Adelaide, Adelaide, Australia
Journal of Sound and Vibration
Volume 455, 1 September 2019, Pages 136-149
doi: 10.1016/j.jsv.2019.05.008
Download original document: “Prevalence of wind farm amplitude modulation at long-range residential locations”
Characterizing tonal amplitude modulation of wind farm noise
Author: Nguyen, Phuc; Hansen, Kristy; and Zajamšek, Branko
[ABSTRACT] In addition to the overall noise level, periodic variations in the loudness of wind turbine noise, known as Amplitude Modulation (AM), also significantly contribute to the annoyance experienced by residents living near wind farms. Due to the high dependence of AM on meteorological conditions and the type of wind turbines, the level and duration of AM are hard to predict. These characteristics have an important impact on the annoyance response of residents. The level of annoyance is expected to depend on the AM depth, the number of AM occurrences and the AM continuity. The aim of this paper is to investigate AM characteristics in the vicinity of two wind farms in South Australia. It has been found that to successfully quantify tonal AM based on the Reference Method proposed by the UK Institute of Acoustics, removing the A-weighting, changing the range of band-pass filter frequency and reducing the prominence ratio are also necessary. AM density at night-time is much higher than at day time (25% versus 15%). However, there is not significant difference between AM depth at night-time and day time. Furthermore, AM is more likely to occur when the wind turbines are operating significantly below their maximum rated power.
Duc-Phuc Nguyen, Kristy Hansen
College of Science and Engineering
Branko Zajamsek
Adelaide Institute for Sleep Health
Flinders University, Bedford Park, Adelaide, SA, Australia
Download original document: “Characterizing tonal amplitude modulation of wind farm noise” (22 MB)
Severe localised grain production losses from atypical frosts in the Marrabel Valley Catchment 2011–2014
Author: Faint, John; and Morris, Mary
For the four cropping seasons from 2011- 2014, a majority of farmers in the Marrabel Valley have experienced unprecedented and widespread frost damage of grain crops on sloping paddocks high above the valley floor. Historically these areas have not been affected by frost as the steep slope of the valley sides ensures that cold air flows towards the lower lying areas where it is normal for frost to form.
The onset of these seasons of atypical and the abnormal frosts and frost damage coincides with the commencement of operation of an 18 km long wind farm which is located on a central ridgeline in the clearly defined catchment area. Four contiguous years of significant production losses have prompted this call for an investigation into whether the wind farm is affecting the near surface meteorology of the Marrabel Catchment. This Catchment covers 21,392 hectares and contains some of the most highly productive and high value cropping land in South Australia, consequently further investigation is justified.
[Submitted to the South Australian Grains Industry Trust (SAGIT), February 2015, as part of a researchapplication, which was not funded. Atypical frosts have continued to occur with millions of dollars worth of damage every year.]
Download original document: “Severe localised grain production losses from atypical frosts in the Marrabel Valley Catchment 2011–2014”
Summary of the Effect of the Medical and Scientific Evidence
Author: White, Richard; and Bean, Katherine
On our analysis, a number of propositions emerge from the medical and scientific evidence. Some of those propositions had unanimous support by the relevant experts, and others had the support of most.
The propositions which we understand have unanimous support from the relevant experts or are not contested include the following:
- Wind turbines emit sound, some of which is audible, and some of which is inaudible (infrasound);
- There are numerous recorded instances of WTN exceeding 40 dB(A) (which is a recognised threshold for annoyance/sleep disturbance);
- There are also recorded instances of substantial increases in sound at particular frequencies when particular wind farms are operating compared with those at times when they are shut down; (Measurements undertaken at the Waterloo wind farm showed that “noise in the 50 Hz third-octave band was found to increase by as much as 30 dB when the wind farm was operational compared to when it was shut down” – Exhibit A51, p 2.)
- If it is present at high enough levels, low frequency sound and even infrasound may be audible;
- WTN is complex, highly variable and has unique characteristics;
- The amount and type of sound emitted by a wind farm at a given time and in a given location is influenced by many variables including topography, temperature, wind speed, the type of wind turbines, the extent to which they are maintained, the number of turbines, and their mode of operation;
- Wind farms potentially operate 24 hours a day, seven days a week;
- There are numerous examples of WTN giving rise to complaints of annoyance from nearby residents, both in Australia and overseas.
469. The propositions which are supported by the preponderance of relevant expert opinion, and which we accept on that basis, include the following: - A significant proportion of the sound emitted by wind turbines is in the lower frequency range, i.e. below 20 Hz;
- The dB(A) weighting system is not designed to measure that sound, and is not an appropriate way of measuring it; (It is even acknowledged in the International Standard, ISO 1996-1 that the A-weighting system alone is “not sufficient to assess sounds characterized by tonality, impulsiveness or strong low-frequency content” – Exhibit A29, T43/8; Section 6.1; “Acoustics – Description, measurement and assessment of environmental noise – Part 1: Basic quantities and assessment procedures”, International Standard ISO (1996-1).)
- The most accurate way of determining the level and type of sound present at a particular location is to measure the sound at that location;
- The best way of accurately measuring WTN at a particular location is through ‘raw’ unweighted measurements which are not averaged across time and are then subjected to detailed “narrow-band” analysis;
- When it is present, due to its particular characteristics, low frequency noise and infrasound can be greater indoors than outdoors at the same location, and can cause a building to vibrate, resulting in resonance;
- Humans are more sensitive to low frequency sound, and it can therefore cause greater annoyance than higher frequency sound;
- Even if it is not audible, low frequency noise and infrasound may have other effects on the human body, which are not mediated by hearing but also not fully understood. Those effects may include motion-sickness-like symptoms, vertigo, and tinnitus-like symptoms. However, the material before us does not include any study which has explored a possible connection between such symptoms and wind turbine emissions in a particular population.
We consider that the evidence justifies the following conclusions:
- The proposition that sound emissions from wind farms directly cause any adverse health effects which could be regarded as a “disease” for the purposes of the ACNC Act is not established;
- Nor, on the current evidence, is there any plausible basis for concluding that wind farm emissions may directly cause any disease;
- However, noise annoyance is a plausible pathway to disease; (We note the World Health Organization has stated: “There is sufficient evidence from large-scale epidemiological studies linking the population’s exposure to environmental noise with adverse health effects. Therefore, environmental noise should be considered not only as a cause of nuisance but also a concern for public health and environmental health”– Exhibit A4, T287/5709, citing “WHO. Burden of disease from environmental noise.” World Health Organization; 2011 [viewed April 2013]; Available from: http://www.euro.who.int/en/publications/abstracts/burden-of-disease-from-environmental-noise.-quantification-of-healthy-life-years-lost-in-europe as referenced by Professor G Wittert in Exhibit 56 NHMRC Draft Information Paper: Evidence on Wind Farms and Human Health, “Expert Review: Comments in full”, National Health and Medical Research Council, February 2015, Appendix 8; and Exhibit 4, T299/6308, Reference No. 40, WHO “Burden of disease from environmental noise”. Bonn: World Health Organization European Centre for Environment and Health, 2011. Available from: http://www.euro.who.int/__data/assets/pdf_file/0008/136466/e94888.pdf.)
- There is an established association between WTN annoyance and adverse health effects (eg. this was established by the Health Canada study);
- There is an established association between noise annoyance and some diseases, including hypertension and cardiovascular disease, possibly mediated in part by disturbed sleep and/or psychological stress/distress; (This is also supported by much of the documentary material before us, including a Victorian Department of Health publication entitled “Wind farms, sound and health”, Technical Information, at 7. How can noise affect our health? – Exhibit A4, T297/6232.)
- There are as yet no comprehensive studies which have combined objective health measurements with actual sound measurements in order to determine for a given population the relationships between the sound emissions of wind turbines, annoyance, and adverse health outcomes. Indeed there is as yet no study which has given rise to a soundly based understanding of the degree to which particular types or levels of wind turbine emissions give rise to annoyance, or what levels or types of emissions are associated with what level of annoyance in the population. Because it relied on calculated rather than actual sound measurements, and was limited to the A and C-weighted systems, the Health Canada study did not do this.
Paragraphs 467–470, File Number 2015/4289
Decision and Reasons for Decision
Administrative Appeals Tribunal, Adelaide
Taxation & Commercial Division
Re Waubra Foundation (Applicant) and Commissioner of Australian Charities and Not-for-profits Commission (Respondent)
The Honourable Justice White, Deputy President
Deputy President K Bean
4 December 2017
