Noise
Town of Bourne Wind Turbine Health Regulation
Introduction
On August the 10th 2011, the Bourne, MA Board of Health adopted a Wind Turbine Health Regulation. It is believed that this is one of a few local boards of health to recognize that wind turbines pose a health hazard requiring regulations to protect the public. In addition to other provisions, the regulation sets limits on the amount of noise measured at the nearest property line.
Bourne vs MassDEP Regulations
Technically, the allowed noise level is equivalent to the general noise pollution level allowed by the Massachusetts Environmental Department’s (MassDEP) noise regulation (310 CMR 7.10). The MassDEP regulation states that a violation occurs if the noise source increases the broadband noise level by more than 10 dB(A) above ambient. The Bourne health regulation applies specifically to wind turbines and limits the increase to 6 dB(A). In addition the regulation defines Amplitude Modulation, and limits this noise component to no more than 4 dB(A) Peak to trough. Amplitude Modulation is a particular characteristic of industrial grade wind turbines known as Aerodynamic Amplitude Modulation (AAM), the cause of which is believed to originate from wind turbulence at or near the tips of the blades.
The graph below serves to illustrate the importance of the AAM limit. The data was collected in Falmouth, MA by a resident, and it shows peak to trough values as high as 12 dB(A), far in excess of the 4 dB(A) limit set by the Bourne health regulation. In addition the peaks are in excess of the 40 dB(A) nighttime cap. The official post construction noise study has declared this wind turbine to be in compliance with the MassDEP noise limit of 10dB(A) above ambient, and this is accomplished by using ambient measurements that are unaffected by the AAM component.
Noise pollution exceeds MA and Bourne BOH limits
By separating the 10 dB(A) limit into two components, the Bourne Health regulation is superior to the MassDEP policy in numerous ways. First of all, the MassDEP policy has been subject to abuse, as applied to wind turbine noise, by the false interpretation of professional acoustic engineering firms.It has become common practice to restate the noise limit as an increase in the ambient level. The regulation clearly limits the broadband sound level increase to 10 DB(A) above the ambient level. Most resident complaints are related to noise from the AAM component. By restating the 10 dB(A)limit as an increase in ambient, acoustical engineers have failed to account for the effect of AAM in both preconstruction studies, and post construction measurements. AAM is a rhythmic (about once per second) sound typically described as a whoosh, whoosh, whoosh sound has little to no effect in increasing the ambient sound level. This has become obvious in the now infamous case in Falmouth, MA. Learning from Falmouth, Bourne has specifically identified AAM, and limits the level to 4 dB(A).The Bourne health regulation will serve to eliminate this most common abuse.
Another problem with the MassDEP policy is that it does not specify any absolute upper limit. By specifying a nighttime upper limit of 40dB(A), the Bourne health regulation could serve to deny permits where noise levels already exceed the limit, and where multiple wind turbine installations result is greater than 40 db(A), even though each one individually may not exceed the limit.
Danger for abuse
While the Bourne Health regulation is a major improvement over MassDEP, the danger for abuse continues to exist. Both regulations require a preconstruction acoustical study to establish compliance. Such studies have been shown to be subject to substantial error. The errors are traceable to at least the following:
- Turbine noise specifications are derived using the IEC 61400-11 standard, which carries no warranty that the figures are maximum levels, and do not report on the level of AAM.
- Computer modeling, used to calculate the propagation of wind turbine noise, accepts as the source input the false assumption that the noise originates at a point source at hub level, and radiates equally in all directions. AAM originates at edges of the wind turbine blades and radiates unevenly as a function of wind direction and speed.
- Noise propagation is affected by many topographical parameters which are subject to judgment error.
As a result, many permits will be issued for wind turbines that will generate excessive noise in violation of the health regulations.
Health departments are not equipped to deal with wind turbine complaints. Proving a violation is an extremely time consuming and expensive process. Data must be collected in the middle of the night, at wind speeds and wind direction that closely matches the conditions existing at the time of the complaint, by an attendant schooled in the science of acoustics. Such conditions are generally not known by resident filing complaints.
Conclusion
Experts who have studied this problem recommend that the better solution is to increase the distance between wind turbines and residential areas. Given the real danger of abuse, it is more practical to follow these expert recommendations that call for setbacks of a mile and a quarter or more.
References:
http://www.windturbinesyndrome.com/img/WindTurbineNoise.pdf
Costs of Mitigation Discussed in Falmouth
Sean Teehan, reporting in the Cape Cod Times, cites the spectacular costs of studying, mitigating, and decommissioning Wind 1 in Falmouth. The price tag ranges from $6,000 for studies to over $1,000,000 because with decommissioning, the town would have to repay the money the Renewable Energy Trust paid the town for future certificates.
But Selectman Brent Putnam put things in their proper perspective. According to the CCT article Putnam said, “In my mind it’s not a large price tag when we’re talking about the well-being of our neighbors.” The neighbors in this case are well within the international guideline of a mile-and-a-quarter setback, and suffer from “noise, low-frequency sound waves, and other effects from the turbines (including) headaches, dizziness, and vertigo among other health problems.”
The 1.65-megawatt turbine is just 1,300 feet from the home of Neil Andersen who is quoted in the piece.
by windwisema August 15, 2011
Article in APA Monitor on Psychology–Jul/Aug 2011–cover story:
Amy Novotney’s article, “Silence, please” notes that “Psychologists are increasing awareness of the harmful effects noise has on cognition and health.”
by windwisema August 6, 2011
Wind Turbine Noise
Noise from utility scale wind turbines and wind farms has resulted in numerous complaints from nearby residents worldwide. Many who have studied this problem have concluded that the only safe solution is to establish setbacks of at least a mile and a quarter.
Once installed, there is nothing that can be done to mitigate the noise short of shutting the turbine down. Furthermore, given the fact that the noise level is constantly changing as a function of wind speed and direction, collecting data to prove compliance is extremely labor intensive and prohibitively expensive.
In Falmouth, Vinalhaven and elsewhere it has taken more than a year to make a determination. The MassDEP is inclined to follow the common practice of using the LA90 metric for all sound measurements. By design, this system registers only the quietest sound levels present 10% of the time. It fails to measure 90% of the Amplitude Modulation (AM), which is the real source of complaints and happens to be the most noticeable and annoying characteristic of wind turbine noise. MassDEP has accepted the argument that measuring the peaks of AM requires an expensive data collection protocol.
In order to gain permit approvals, wind industry proponents insist on the use of supposedly “ scientific” methods, such as that contained in the New Zealand Standard NZS 6808:2010. These standards are used to predict safe noise levels on a case-by-case basis. However, standards and local by-laws like these suffer from a number of false assumptions. These include a limited range of data in the case of published noise emission reports and the exclusion of relevant AM sound data when modeling is used.
A major source of error is the accuracy of the published noise emissions from a given wind turbine. The published figures are derived using the IEC 61400-11 standard, which carries no warranty that the figures are maximum levels. The main purpose of IEC 61400-11 is to provide reproducible results at wind speeds between 6 and 10 meters per second which can be used to compare different wind turbine models.
The IEC 61400-11 standard procedure collects sound data at some distance from the turbine which are used to calculate the sound power level from a virtual point at hub height. In fact, the major source of the offending AM noise is generated at the extremities of the rotor blades which is at some distance from the hub center and radiates outward at broad angles from the direction of the wind.
Computer modeling, used to calculate the propagation of wind turbine noise, accepts as the source input the false assumption that the noise originates at a point source at hub level, and radiates equally in all directions. This assumption results in grossly under-predicting, by orders of magnitude, AM noise levels at the various receptor sites around a turbine.
The complexities of the so-called scientific method favored by the wind industry are open to manipulation and abuse. Add to that the next-to-impossible task of proving post-construction compliance. This leaves, as the only reasonable approach, the acceptance of the expert studies that recommend a setback distance of a mile and a quarter or more as the best way to protect the public from the extreme annoyance, and the ill health effects from wind turbine noise.
The fact that some people, who live in close proximity to wind turbines, can tolerate the noise without apparent annoyance or ill effects is interesting. However, this does not diminish the many claims of those whose experience is to the contrary. There can be any number of explanations as to why people are affected differently, but for now the focus needs to be on the significant number of people living within a mile of wind turbines who not only find them annoying, but argue that the noise is the cause of sleep disturbance, headaches and other ailments.
References:
http://www.ecoawarenesssociety.ca/research/resources/EAS%20SW%20Noise%20Analysis%20Critique.pdf
http://www.windturbinesyndrome.com/img/WindTurbineNoise.pdf
http://www.acousticecology.org/newsarchive/newsarchiveurban.html
http://www.acousticecology.org/srwind.html#Anchor-49575
http://acousticecology.org/docs/AEI_WindFarmNoise_2009inReview.pdf
http://www.renewableenergyworld.com/rea/news/article/2010/03/listening-to-wind-farm-noise-concerns
http://concernedcitizens.homestead.com/files/windfarms/noise.html
http://www.windaction.org/?module=uploads& func=download& fileId=2021
http://www.savewesternny.org/docs/pierpont_testimony.html
http://saveourseashore.org/?p=641
http://docs.wind-watch.org/simple-guidelines-for-siting-wind-turbines-to-prevent-health-risks.pdf
http://www.abajournal.com/magazine/article/the_war_of_winds/
http://www.windtaskforce.org/video?page=3
http://www.acousticecology.org/docs/AEI%20Wind%20Turbine%20Noise%20FactSheet.pdf
http://pandorasboxofrocks.blogspot.com/2010/10/guidelines-for-selecting-wind-turbine.html
http://kirbymtn.blogspot.com/2008/07/safe-setbacks-how-far-should-wind.html
http://sites.google.com/site/montvillewind/home/findings-rationale/setbacks
http://docs.wind-watch.org/McCann-Setbacks-property-values.pdf
http://abelaw.homestead.com/files/wind/Horizon_project/CCCC_ltr._to_Machias_8-28-09.pdf
http://www.windaction.org/documents/18164
Wind Wise ~ Massachusetts 