Documents
Noise
Noise is defined as any unwanted sound. Concerns about noise depend on 1) the level of intensity, frequency, frequency distribution and patterns of the noise source; 2) background noise levels; 3) the terrain between the emitter and receptor; and 4) the nature of the noise receptor. The effects of noise on people can be classified into three general categories (National Wind Coordinating Committee, 1998):
1) Subjective effects including annoyance, nuisance, dissatisfaction
2) Interference with activities such as speech, sleep, and learning
3) Physiological effects such as anxiety, tinnitus, or hearing loss"........
prepared by the Renewable Energy Research Laboratory Center for Energy Efficiency and Renewable Energy Department of Mechanical and Industrial Engineering University of Massachusetts at Amherst
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.
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. "
"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."
Stockholm, August 2003
SWEDISH ENVIRONMENTAL PROTECTION AGENCY Report 5308
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…”
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."
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