Documents filed under Noise
Low Frequency Noise Low frequency noise is generated at very low frequencies, generally accepted to be at levels below 100 Hz and the audible range. There is presently no commonly accepted metric or standard for measurement, although several have been proposed or used in specific situations. Low frequency noise has been associated with wind turbine developments, as well as road, rail, sea and air traffic and other industrial applications such as cooling towers. It creates a large potential for community annoyance, and it is most often experienced inside of homes and buildings where resonance amplifies the sound, which is less easily heard outside. Because the frequencies are so low, the noise is often “felt” as a vibration or a pressure sensation. Reported effects include annoyance, stress, fatigue, nausea and disturbed sleep. Low frequency noise can be a factor at much greater distances from the noise source than audible noise. A case study in North Carolina in the 1980’s near a wind turbine installation documented low frequency noise problems at residences located over ½ mile from the turbine.2 While the phenomenon was originally believed to be associated with the older, down-wind designed turbines, the problem persists with newer wind farms. It has received particular attention in Denmark, and has been a topic considered in the UK, Scotland and Wales through a commissioned government project in 2001.
3.8 Health & Safety Affected Environment, Environmental Impacts and Mitigation Measures "A number of comments submitted for the scoping process for the Desert Claim project EIS addressed concerns relating to potential health and safety issues. Specific topics indicated in these comments included certain possible hazards that are uniquely associated with wind turbines, such as blade throw and ice throw; health and safety issues associated with electrical and magnetic fields; more common hazards such as fire; and the incidence and impacts of shadow flicker, another phenomenon specific to wind turbines. Section 3.8 addresses these wide-ranging health and safety topics that have been identified as concerns for the environmental review. "
This significant research by van den Berg explains why turbine noise as far away as 1900 meters (more than 6,000 feet) is resulting in complaints by residents particularly at night. The paper concludes that noise immission predictions are not accurate and result in the understating of turbine noise levels, particularly during nighttime conditions.
Journal of Sound and Vibration "Since the start of the operation of a 30MW, 17 turbine wind park, residents living 500m and more from the park have reacted strongly to the noise; residents up to 1900m distance expressed annoyance. To assess actual sound immission, long term measurements (a total of over 400 night hours in 4 months) have been performed at 400 and 1500m from the park. In the original sound assessment a fixed relation between wind speed at reference height (10 m) and hub height (98 m) had been used. However, measurements show that the wind speed at hub height at night is up to 2.6 times higher than expected, causing a higher rotational speed of the wind turbines and consequentially up to 15 dB higher sound levels, relative to the same reference wind speed in daytime. Moreover, especially at high rotational speeds the turbines produce a ‘thumping’, impulsive sound, increasing annoyance further. It is concluded that prediction of noise immission at night from (tall) wind turbines is underestimated when measurement data are used (implicitly) assuming a wind profile valid in daytime."
Wind power is a relatively new generator of electricity in Sweden. Legislation and regulation regarding noise from wind turbines in Sweden have been discussed. Eja Pedersen at Halmstad University has at the request of the Swedish Environmental Protection Agency prepared this report as a base for further discussions on regulation and guidelines on noise from wind turbines in Sweden. The report reviews the present knowledge on perception and annoyance of noise from wind turbines in residential areas as well as in recreational areas. It also summarizes regulations in some European countries. The author Eja Pedersen is responsible for the content of the report. Stockholm, August 2003 SWEDISH ENVIRONMENTAL PROTECTION AGENCY Report 5308
Dr. Richard Truly, Director, National Renewable Energy Laboratory Dear Dr. Truly: It has come to my attention that an employee of the National Renewable Energy Laboratory (NREL), Mr. Larry Flowers: 1. Asserted, during public “forums” on wind energy held on March 25, 2003, in Ludington, Michigan, that I am in some way associated with the coal industry and, therefore, my analysis and writing concerning wind energy should not be considered credible. Over 150 people attended these public forums. 2. On March 27, 2003, distributed via email to one or more participants in the Ludington forums the attached undated, unsigned paper which questions the independence of my work, questions the truthfulness of my claim that my work on wind energy is self-financed, and makes other false and misleading statements. Mr. Flowers’ email forwarding the paper includes the following statement: “MI wind colleagues: here is a brief piece written in response to Glen [sic] Schleede misinformation. I suggest you distribute this to participants in the Ludington meeting…”
"This document aims to help developers, planning and enforcement authorities, other government agencies and the broader community assess environmental noise impacts from wind farms. The core objective of these guidelines is to balance the advantage of developing wind energy projects in this State with protecting the amenity of the surrounding community from adverse noise impacts. Wind farms need specific guidelines because wind turbines have unique noise generating characteristics and the environments surrounding wind farm sites usually have low ambient noise."
Kelly Alexander believed that windpower would be a good energy source. He was told the machines were not noisy. No one told him about the blade flicker that shines even through closed blinds or the low frequency noise that penetrates his home with doors and windows tightly closed and storm windows installed. Recently, the turbine owner visited Kelly and asked what he could do to help the situation. He said, “Stop lying about these turbines. Tell people the truth.”
Thank you for your enquiry about wind farm noise. I should probably explain my background and interest in wind farms. I have been a noise and acoustic consultant for more than 30 years and most of my current work is dealing with the assessment of environmental noise as it affects residential properties. I work equally for those potentially creating noise and those affected by it. I have been a supporter of wind energy and other forms of renewable energy for some 35 years. I have carried out noise assessments for both “sides” in planning applications for wind farms and adopt the same method of assessment whoever employs me.
This paper describes a case study in which low frequency noise (LFN) was suspected of causing disturbance in a semi-rural location close to an industrial estate. Previous attempts using conventional acoustic measurement techniques to resolve the case, or even prove the existence of a real acoustic problem, had proved unsuccessful. The study does not involve wind turbine noise directly, but the work done and resulting findings provide insight into identifying the problem of LFN and predicting annoyance.
Lincoln Township in Wisconsin sent a survey to its residents to help assess the impacts of 22 turbines installed by Wisconsin Public Service Corporation (WPSC) and Madison Gas and Electric (MG&E), which went online in June 1999. A summary of the survey comments received is provided in the attached document. After the wind turbines went online, the Lincoln Township Board of Supervisors approved a moratorium on new turbine construction.
Dr. David M. Lipscomb PhD provided this testimony before the State of Washington Energy Facility Site Evaluation Council involving the risks of noise emissions from then proposed Sumas Generating Plant on human health. An excerpt of the testimony is provided below. The full testimony can be downloaded by clicking on the link at the bottom of this page.
This WHO document on the Guidelines for Community Noise is the outcome of the WHO- expert task force meeting held in London, United Kingdom, in April 1999. It bases on the document entitled “Community Noise” that was prepared for the World Health Organization and published in 1995 by the Stockholm University and Karolinska Institute.
The document critically reviews the adverse effects of community noise, including interference with communication, noise-induced hearing loss, annoyance responses, and effects on sleep, the cardiovascular and psychophysiological systems, performance, productivity, and social behavior. Noise measures or indices based only on energy summation are not enough for the characterization of most noise environments. This is particularly true when concerned with health assessment and predictions. It is equally important to measure and display the maximum values of the noise fluctuations, preferably combined with a measure of the number of noise events, and to assess whether the noise includes a large proportion of low frequency components.
This paper, presented at the Windpower ’87 Conference & Exposition in San Francisco by N.D. Kelley, a physicist at the Solar Energy Research Institute in Golden, Colorado validates the fact that turbines (both upwind and downwind) produce low-frequency sound emissions that can negatively impact humans within their homes. Although modern wind turbines are different from those studied in 1987, the research is significant in that it demonstrates the need to test for low-frequency sound emissions and to do so inside buildings.
This report summarizes extensive research by staff of the Solar Energy Research Institute and its subcontractors conducted to establish the or1g1n and possible amelioration of acoustic disturbances associated with the operation of the DOE/NASA MOD-1 wind turbine installed near Boone, North Carolina. Results have shown that the most probable source of this acoustic annoyance was the transient, 'unsteady aerodynamic lift imparted to the turbine blades as they passed through the lee wakes of the large, cylindrical tower supports. Nearby residents were annoyed by the low-frequency, acoustic impulses propagated into the structures in which the complainants lived. The situation was aggravated further by a complex sound propagation process controlled by terrain and atmospheric focusing. Several techniques for reducing the abrupt, unsteady blade load transients were researched and are discussed.
This document has been prepared by Terry Matilsky, Professor of Physics at Rutgers University. For almost 40 years, he has been funded by NASA and other federal agencies to do data analysis from various scientific satellites; to examine what information tells us about a phenomena, and draw rational and solid, scientific conclusions from them.