Resource Documents: Regulations (249 items)
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Author: West, Michael
Despite their generally positive reputation as sources of clean, safe energy, Industrial Wind Turbines (IWTs) do have their critics. For years, residents living in the vicinity of IWT clusters have reported a variety of physical ailments which they attribute to the sounds and vibrations emanating from wind turbines (Kelley, 1985; CBC.ca, 2011). Noise bylaws, setback distances and other regulations applied to IWTs appear to be based on analysis methods used historically with industrial applications, where noise tends to be constant or semi-constant and in the audible range. The noise generated by IWTs is quite different – spiky and high amplitude – like an exploration seismic source pulse, and mainly found in low frequencies not detectable by human hearing (i.e. infrasound or “below hearing”). This article looks at the signals generated by IWTs from a geophysicist’s perspective. …
The analysis of the operating IWTs on the ground and the seismic and air-pulse recordings confirms that large horizontal axis Industrial Wind Turbines act like airgun seismic sources that create low frequency pulses approximately once per second. The audible part of the air pulse makes a sound like “whump” so, as per geophysical industry tradition, we should name the IWT a “whumper” seismic source (as opposed to a thumper or puffer which would require a faster rise-time on the pulse). Most of the amplitude of the pulse exists at frequencies below the audible range, so a person stopping by the roadside to listen to an IWT may not hear anything and is likely to think that they make no significant “noise” at all.
Two aspects of IWT-generated noise do not appear to have been adequately accounted for in the creation of regulations for the IWT industry: that the noise contains many spurious, high amplitude spikes, and that it is mainly found in the low, infrasonic frequencies. An impulsive noise source such as an IWT requires amplitude measurements over short time windows like 1 second and little or no averaging of data during analysis. Long analysis time windows and averaging amplitude over 1/3 octave band frequency ranges is an acoustics industry testing method appropriate only for higher frequency “whirring” machines like diesel generators or milling machines. Current Ontario Government regulations do not include testing frequencies lower than 31.5 Hz. “Noise” testing procedures for regulation of IWTs should be revised to include all low frequencies created by the IWTs because the low frequency events contain the most power and highest amplitudes.
Conversion of non-weighted peak pulse amplitudes from the microphone recording in Figure 9, at 550 meters offset in 20 kph winds including the full frequency range to 1 Hz, revealed peak Sound Pressure Levels of 65 dB or more. Additionally, the SPL noise limit specification should not be increased with increased wind speed as this makes no sense. Governments and agencies tasked with the regulation of IWT installations should review and revise their testing protocols, so that regulations that reliably protect the health of people and animals living in the vicinity of IWTs can be implemented.
Michael West, P. Geoph., B.Sc., GDM
Canadian Society of Exploration Geophysicists | Recorder, Jun 2019, Vol. 44, No. 04
Download original document: “The Industrial Wind Turbine Seismic Source”
Author: Overland, Carol
Minn. R. 7030.0400 is the MPCA’s noise rule, setting standards for industrial noise. It was developed to limit industrial noise, from a noise source on the ground to a “receptor” on the ground. ISO 9613-2 was also developed to measure ground based noise reaching a ground based receptor.
A primary input is the “ground factor” set to address conditions on the ground, the ground effect, between the noise source and the receptor:
7.3 Ground effect (Agr)
7.3.1 General method of calculation
Ground attenuation, Agr, is mainly the result of sound reflected by the ground surface interfering with the sound propagating directly from source to receiver.
While there may be some reflected sound reaching the “receptor” (that is such an obnoxious term for people!), the sound from a wind turbine with a hub height of 300 feet or more! That’s a direct path to the “receptor.” The ground, grasses, corn, trees, buildings, do not get in the way.
The ground factor to be used for wind turbines is ZERO.
Dr. Schomer stated this clearly and thoroughly in the Highland Wind docket in Wisconsin (PSC Docket 2535-CE-100).
The use of a 0.0 ground factor for wind is standard practice, and that a 0.5 ground factor is NOT appropriate for wind because it’s elevated. This was inadvertently confirmed by Applicant’s Mike Hankard in the Badger Hollow solar docket, also in Wisconsin (PSC Docket 9697-CE-100):
The model that we use has been shown to predict conservatively with 0.5. I mean, 0.5 ground factor is used in probably – well, with the exceptiion perhaps of wind turbine projects which are different because the source is elevated. But for projects like a typical power plant, a solar plant where the sources are relatively close the ground, I would say 90 to 99 percent of the studies use 0.5. And when consultants like myself go out ad measure these plants after they’re cpmnstricted tp verify our modeling assumptions, that assumption checks out as being, if anything, overpredicting the levels. So there’s no need to – there would be no justification to use something like a .2 or .3 which would predict yet higher levels because we’re already demonstrating that the model is probably overpredicting. So that would not be justified for those reasons.
Who cares? Well, it’s bad enough that in that WI PSC Highland Wind docket, when the applicants couldn’t comply with the state’s wind noise limit, they redid their noise “study” using the inappropriate ground factor of 0.5 to give them more compliant numbers – they moved the goal posts, garbage in, garbage out. They think they can do that in Minnesota too, and are trying oh so hard in the Freeborn Wind docket (PUC Docket 17-410).
Last September, 2018 that is, Freeborn Wind did a deal with Commerce, admitted to in its “Request for Clarification/Reconsideration” pleading:
Freeborn Wind requests the Commission clarify its Site Permit to adopt Section 7.4, as proposed by Freeborn Wind and agreed to by the Department and MPCA, in place of the current Sections 7.4.1 and 7.4.2, to both ensure consistency with the Order and avoid ambiguity in permit compliance.
Freeborn Wind’s September 19, 2018, Late-Filed proposal for Special Conditions Related to Noise outlines the agreement reached between Freeborn Wind, the Department and the MPCA on this issue.
(fn. citing Late Filed—Proposed Special Conditions Related to Noise (Sept. 19, 2018), eDocket No. 20189-146486-01).
In this deal, they put language in the permit that was a fundamental shift in noise monitoring, one for which there is no justification under the noise modeling standards, whether state or ISO 9613-2 – that of using a 0.5 ground factor.
The language in the proposed special conditions requires Freeborn Wind to submit updated modeling and/or proposed mitigation demonstrating that modeled wind turbine–only noise will not exceed 47 db(A) L50-one hour at receptors. Specific guidance is included regarding the modeling assumptioins to be used. Specifically, proposed Section 6.1 directs Freeborn Wind to follow the NARUC ISO 9613-2 standard with a 0.5 assumed ground factor. As reflected in the special condition language, setting a turbine-only noise limit at 47 dB(A), using the specified model assumptioins, ensures that the Project will not cause or significantly contribute to an exceedance of the MPCA Noise Standards. This limit is supported in this record by expert testimony from Mr. Mike Hankard and the MPCA’s 2015 Noise Guide, both stating the 3 dB(A) is the generally recognized minimum detectable change in environmental noise levels. To illustrate, when nighttime background sound levels are at 50 db(A) L50-one hour, a maximum turbine-only contribution of 47 db(A) L50-one hour would result in a non-significant increase in total sound of less the 3 dB(A).
The day before the Commission’s meeting, they filed for a “Special Condition,” and oh, was it special:
At the meeting, they presented a chart with made up numbers on it, not supported by any noise study:
This chart was shown for a few seconds at most, it was not provided in the “Late Filing” above, and there were no copies for parties or the public. Did Commissioners get a copy? Who knows …
The Commission then granted the site permit! There were a few rounds before we got to where we are today, with Xcel Energy acquiring the project, and with a new site plan, bigger turbines, and some specific site permit amendments. In its permit amendment application, Xcel Energy is now the owner of Freeborn Wind, and Xcel wants to use larger Vestas V120 turbines rather than the V116.
From testimony in the original Freeborn Wind hearing, and in an Affidavit submitted by Commerce-EERA’s Davis:
7. It is generally understood that turbine noise output increases with higher blade tip speeds …
(Aff. of Davis, EERA Motion, 20181-139379-01)
In its permit amendment application, Xcel Energy is now the owner of Freeborn Wind, and Xcel wants to use larger turbines. In so doing, they have filed a noise study, Attachment E, utilizing that 0.5 ground factor. Xcel’s claim is that they’re using a 0.5 ground factor because the permit specifies that:
This Xcel filing is the first noise study in the Freeborn Wind record to utilize a 0.5 ground factor.
This Xcel filing is the first noise study in the Freeborn Wind record following the ALJ’s recommendation of denial:
The Administrative Law Judge concludes that Freebron Wind has failed to demonstrate that the proposed Project will meet the requirements of Minn. R. 7030.0040, the applicable Minnesota Noise Standards. Therefore, the Administrative Law Judge respectfully recommends that the Commission either deny Freeborn Wind’s Application for a Site Permit, or in the alternative, provide Freeborn Wind with a period of time to submit a plan demonstrating how it will comply with Minnesotat’s Noise Standards at all times throughout the footprint of the Freeborn Wind Project.
There’s a 3 dB(A) margin of error – even using Hankard’s numbers, look at the yellow lines right up against the homes, and look at the blue 50 dB(A) lines and how many homes are inside of those lines:
Turbine noise at the hub for the V120s can be maximum of 110.5 dB(A), and serrated edges provide an option to reduce noise (which Xcel says it plans on using for some turbines), per the Vestas spec sheet.
Compliance? Modeling with the improper 0.5 ground factor doesn’t come close to demonstrating compliance, instead it demonstrates a high probability of non-compliance. It demonstrates that using the proper ground factor for wind, it won’t do the modeling, likely (assuredly) because the project cannot comply. Freeborn Wind could not demonstrate that it could comply with state noise standards as originally designed with the smaller wind turbines and the proper modeling ground factor, and now Xcel Energy wants to use larger turbines. Larger turbines are noisier … once more with feeling:
7. It is generally understood that turbine noise output increases with higher blade tip speeds …
And now we see, hot off the press, the Plum Creek wind project (PUC Docket WS-18-700), proposed by Geronimo …
Vestas 150 and 162 turbines, 5.6 MW each! The noise for the V150 is a maximum of 104.9 dB(A), and for the V162 is a maximum of 104.9 dB(A), with “sound optimized modes available.” That’s in the brochure.
They have provided a noise study, BUT, much is NOT PUBLIC:
And I wonder why … well, it says that they’re not using a ground factor of 0.0. Look at p. 48 of the sound study above, deep breathe and take a peek:
They’re using a ground factor of 0.7 !
For this analysis, we utilized a ground factor of G=0.7, which is appropriate for comparing modeled results to the L50 levels.
18A 2-dB uncertainty factor was added to the turbine sound power per typical manufacturer warranty confidence interval specifications. 18Generally accepted wind turbine modeling procedure calls for a ground absorption factor of G=0.5, with a 2-dB uncertainty factor added to the manufacturer’s guaranteed levels, to predict a maximum LEQ(1-hr). In this case the state limit utilizes and L50 metric instead of maximum LEQ(1-hr), which means a ground factor of G=0.7 can be used.
They say it again on p. 62, elsewhere too:
How stupid do they think we are?
How stupid do they think Commerce-EERA is? … oh … never mind …
Anyway, here are the sound study maps based on that bogus 0.7 ground factor – look how many homes are affected:
Geronimo gets the gong:
The applicants know exactly what they’re doing.
At least twice in the Freeborn record I have asked whether the Commissioners understand “0.5 ground factor” and “0.0 ground factor” and have been vigorously assured that yes, they do understand. And Commerce-EERA staff? You’re responsible for doing the footwork on these siting applications. Do you understand?
If they do not understand, or misunderstand, they’ve got some learnin’ and edumacation to do. If they DO understand, and are approving site permits knowing that the modeling is off, that ground factor is misused, they’re complicit. They’re knowingly afflicting those who have to live with the noise sound levels that exceed Minnesota state standards.
As we saw in Bent Tree, where the noise standard compliance is in question, it is Commerce’s job to do the noise monitoring and deal with the problem. Once a turbine is up, there aren’t many options other than “shut down the turbines” or “buy out the landowners.” How many landowner buy-outs do you think we need before it’s admitted there’s a problem? Why is it so hard to develop responsible, precautionary, and respectful siting? Why is there resistance? The costs of their failure to do so are … well … we may see exactly what those costs are.
Commissioners and Commerce staff, make sure you know how the state noise standard and ISO 9613-2 was designed, how it is to be used, and what ground factor means.
If you know what it means, and are siting turbines using 0.5 and 0.7, you are responsible.
Author: Cooper, Steven
The issue of an updated noise guideline for wind farms in South Australia represents the third (public) attempt at the Environment Protection Authority (EPA) to address wind turbine noise and unfortunately still contains significant errors and omissions as to to fundamental requirements with respect to the protection of the amenity of residents in proximity to wind farms.
Despite complaints from residents and documentation in relation to such complaints, the EPA have not established appropriate criteria to protect the acoustic amenity of residents. …
The guidelines do not identify what level of noise, or what noise characteristics, will result in sleep disturbance. Assuming that most people will sleep indoors, then Section 2.3 identifies that sleep disturbance is likely to be considered inside as an unreasonable interference that in turn could create an adverse health impact. Section 2.3 is silent on what is a sufficient outdoor amenity to not create an adverse health impact. … There is no information to identify what wind turbine noise levels and characteristics create and adverse impact for hosts or non-hosts. … Without this material provided in the noise guidelines then there is absolutely no way that any environmental assessment can be undertaken for a wind farm and identify that there will be no adverse noise impact. … There is no material to support the limits specified in the guidelines, and in light of no dose-response data for wind turbines, the matter of not identifying the precautionary principal in creating a noise guideline in relation to wind turbines is not acceptable.
In relation to fulfilling the ethical and moral obligations of acousticians to rural communities in proximity to wind farms, research has been conducted by multiple researchers including Professor Colin Hansen, Associate Professor Con Doolan, & Dr Kristy Hansen at Adelaide University & Flinders University, Dr B Thorne, Mr L Huson and the author into what constitutes the acoustic signature of wind turbines and how it is impacting upon people. The Adelaide University researchers conducted almost all of their research at Waterloo Wind Farm in South Australia, and have published a text book as well as multiple peer reviewed published papers. There is no reference to any of that material in the bibliography to the draft guidelines … In addition to the failure of the SA EPA to establish the acoustical basis of the core objectives and how the nominated levels will protect the community for adverse noise or health impacts there a technical issues in the guidelines that question the technical capability of the SA EPA to fulfil their obligations to protect the rural community from adverse noise impacts from wind turbine installations.
There is general agreement in acoustic Standards that there is a distinct different degree of sensitivity to noise by residential receivers during the night to that in the day. There are many Acoustic Standards throughout the world in relation to industrial noise and transportation noise where there is a different weighting (for different acoustic descriptors) applied to noise events that occur in the night-time period when compared to the daytime period. …
The concept for wind turbines of using a generic criteria based upon 24-hour measurements would appear to be inconsistent with general environmental assessments, in that there is an expectation of lower background levels and therefore lower criteria for the night time periods. Background levels at night are typically lower than in the day. Yet the draft guideline does not acknowledge this fact by providing different criteria.
Generally for a wind farm application, with respect to wind data monitoring of the wind for a proposed wind farm is undertaken over a number of years. Therefore, the concept of utilising two weeks of noise data for establishing criteria for a wind farm would appear to be inadequate and not appropriately considered by the EPA.
The difference in prevailing wind for a site or receiver location for the different seasons of the year may be significant in terms of both the assessment of the background level and the predicted noise levels. Such differences are not appropriately reflected in a regression averaging technique based upon hub height wind speeds without any identification of wind direction or seasons.
In the determination of noise criteria for other noise sources such as industry for transportation, the use of dose response curves determines criteria based around 10% of the population seriously or highly affected.
One concept presented in New South Wales by the EPA and Department of Planning is to establish criteria to protect 90% of the population 90% of the time and in that regard ambient background level is expressed in terms of the lowest 10 percentile of the background levels.
It is upon that lowest 10 percentile background level upon which in NSW the background +5 dB(A) limit as a general criterion is based. …
Section 4.7 (Annoying characteristics) repeats the previous errors (in the current and original version of the guideline) in relation to infrasound and clearly an inadequate literature research that indicates that is not a problem.
The suggestion in Section 4.7 that amplitude modulation or low frequency noise is not expected to impact upon receivers during a substantial fraction of the year is incorrect. …
Amplitude modulation by definition is the variation in the level of a carrier frequency where the variation in the level of that carrier frequency (described as modulation) occurs due to a much lower frequency. …
For a wind turbine when one is utilising the correct terminology, amplitude modulation can be related to the output shaft speed of the gearbox (where that tone is the carrier, as a clear and distinct tone) that is modulated at the rate of the blade pass frequency. Depending upon the turbine model the carrier frequency may be at for example, 25.5 Hz, 26 Hz or 31.5 Hz. A narrowband frequency analysis of the signature reveals side bands (to the gearbox output shaft frequency) that clearly satisfy the definition of amplitude modulation [link].
However, the audible noise associated with the “swish” or “thumping” noise is not amplitude modulation (by definition) but is a “modulation of the sound” as identified in the New Zealand Standard as a special audible characteristic. One would have expected the SA EPA to have understood the difference between amplitude modulation and modulation of the sound.
The use of the dB(A) level cannot, by definition be considered as a single frequency because it is a result of multiple frequencies. The dB(A) level can be seen to be modulated at the rate of the blade pass frequency. Therefore, the modulation (variation) of the dB(A) level cannot be called amplitude modulation. The periodic variation on the amplitude of the dB(A) is a modulation of the dB(A) level, where the modulation occurs at an infrasound rate. …
Additionally, it must be noted that determining “compliance” by use of a L90 average level would not account for the modulation of the acoustic signal. The time signature of a wind turbine identifies a series of pulses which occur at the blade pass frequency. The blade pass frequency is in the order of 0.86 Hz for a three bladed turbine operating at 17 rpm.
Therefore, there are questions as to whether infrasound as a concept of sound itself is generated by wind turbines [link1; link2]. As such the concept of audibility or effects from infrasound as suggested in the guideline may not be appropriate. The threshold of audibility for a tone is different to that of a pulse, especially in the infrasound region [link]. Research work and investigations undertaken by the author (by testing conducted in a chamber that could produce infrasound pure tones down to 1 Hz) identified that there is a difference in terms of the perception of infrasound for pure infrasound tones on a constant basis versus pulsations. There is also a hysteresis effect in the thresholds (for both sensitivity and hearing) when increasing the level of infrasound versus decreasing the level [link]. Additional work undertaken by the author has identified the provision of signals recorded in houses in proximity to wind farms and specifically using filters to prohibit any sound below 40 Hz into the speakers, to find that digital frequency analysis of the signal will show the presence of a signature in the infrasound region by way of the incorrect analysis of the pulsations, when in fact there is no infrasound present [link]. …
The suggestion in Section 4.7 of the draft guideline that annoying characteristics are not fundamental to a typical well-maintained wind farm is incorrect. In the UK there have been efforts to define “excessive amplitude modulation” in light of the increase in annoyance that identifies the above SA EPA claim of annoying characteristics is incorrect. Often residents complain that they hear (generally inside the dwelling but also external to the dwelling) on a continuous basis a low frequency noise when the turbines are operating, with the description typically expressed as a plane that never lands.
The development of wind farms in South Australia has resulted in the creation of a new industrial noise source that gives rise to disturbance to rural residents.
With the benefit of hindsight, it is apparent that the guidelines introduced by the South Australian EPA were not based upon actual wind turbine noise but on criteria for other noise sources without identifying the differences between those established noise source sources and wind turbine noise. Over the ensuring period the size of wind turbines has increased and so has the impact. Therefore one questions the relevance of original work on wind turbine noise carried out in Europe on turbines with significantly lower capacity.
From the outset, the South Australian wind farm guidelines had failed to provide material that identifies how the objectives of the guidelines are satisfied, by not identifying what acoustic impacts occur or adverse health impacts that occur as a result of the operation of wind turbines.
On a statistical basis, the number of complaints from communities in proximity to wind turbines is well above the norm and as such cannot be ignored by any regulatory authority if acting to protect the amenity of residents.
The principal issue that the author has experienced in attending residential properties with respect to wind farms is that residents report sleep disturbance. There appears to be a deterioration over time for some people that are impacted. It is noted that not all people are impacted by wind turbines which is compatible with an analogy for seasickness. …
There is often an excuse provided that there are no studies to show that wind farms create health impacts, which can also be said in the reverse case that there are no studies to show there are no health impacts. Because there is a lack of studies.
Work undertaken by the author has identified that in a laboratory situation persons who have become sensitised to wind turbines can detect the presence of a wind turbine signal even though it is inaudible [link]. I am advised by persons who have been adversely affected by wind turbines to the point of having to relocate from their properties (permanently or regularly) and who have recently participated in testing undertaken by Flinders University that in terms of the sleep study they have experienced disturbed sleep.
Further work by the author in relation to the investigation of fluctuations (that is not just restricted to wind turbine noise) reveals that the presence of excessive modulation, which occurs on a regular basis from wind turbines, gives rise to a greater level of annoyance which should be added to the A-weighted levels with respect to wind turbine noise [link].
Download original document: “South Australia Wind Farm Guidelines Consultation”
Author: Thorsson, Pontus
In most countries there are regulations of wind turbine sound level outdoors at dwellings. Often there are also regulations of the sound levels inside the dwelling, however not often directly aiming at wind turbine sound. The sound level indoors from wind turbines has attracted more interest in the latest years, and then especially in the low frequency region (up to 200 Hz). Studies on the in situ sound level difference between outside and inside of dwellings are however scarce. This paper presents the in situ measured sound level difference for two Swedish houses in rural locations, both using a loudspeaker and using the wind turbine sound as exciting signal. This is possible due to a 2 month long measurement series with simultaneous sound recordings outside and inside. The sound pressure level differences from the two methods are shown to differ substantially.
Pontus THORSSON, Akustikverkstan, Lidköping, Sweden
Proceedings of the 23rd International Congress on Acoustics, 9–13 September 2019, Aachen, Germany: pages 3826-3830
Download original document: “In situ measured facade sound insulation of wind turbine sound”