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Will Serrated Edges Slice Turbine Noise at the Hoosac?

November 2, 2014
Serrated TE installation  rigging at Hoosac

Credit: Larry Lorusso, used with permission

As the installation of new turbine blade edges began in Monroe last week (October 25, 2014), residents of Monroe and Florida can only hope that the saw-toothed edges will make a dent in the turbine noise plaguing them. An industrial-sized crow’s nest allowed technicians to apply GE’s experimental fix for Iberdrola’s out-of-compliance turbines. The blade being worked on in the photo at left is in the top middle of the frame. Below is a close-up of the “Serrated TE” GE uses to reduce blade noise.

Credit: Larry Lorusso, used with permission

Credit: Larry Lorusso, used with permission

According to a letter and report from Iberdrola to the MassDEP, the violations at the Hoosac ranged from 10.2 dBA above background in January 2014 to 17 dBA in February. The Serrated TE reduces broadband noise by 2 to 4 dBA according to Totaro & Associates of Houston Texas.

This is the first time an attempt has been made to mitigate turbine noise in Massachusetts while keeping the turbines running. Previous orders have required shut downs for certain hours of operation. The serrated trailing edge retrofit allows the wind turbine operator to continue to produce electricity while testing an unproven noise reduction technology.

According to Jim Cummings in”Addressing Wind Farm Noise Concerns” (Acoustic Ecology Institute, Dec 2012):

Aerodynamic noise from the trailing edge of turbine blades is the primary noise source of most modern turbines. This is generally a broadband noise, though most notable at frequencies of 700Hz to 2kHz. A range of design modifications are being developed by most turbine manufacturers, including shape of the airfoil, tip modifications, vortex generators along the fin’s crest, and porous or serrated trailing edges. Serrated edges appear to be the most widely studied, with overall noise reductions of 3-8dB being reported (Barone, 2011). However, many studies have found that these reductions are frequency-dependent, with reductions in low-frequency noise and increases at higher frequencies (over 2kHz). Serrations may be less effective at low or moderate wind speeds; in some situations, this can be when neighbors find turbine noise most audible.

Residents have filed multiple complaints to the MassDEP regarding the noise experienced West of Bakke Mountain, in Florida and Clarksburg, and on Moores and Tilda Hill roads in Florida and Monroe. However Iberdrola is only installing serrated edges on half the turbines on its industrial wind complex, meaning that those affected by Bakke Mountain turbines will not benefit.Hoosac-Report-map_Figure-1

Although noise and the consequent lack of sleep are the primary concerns for people living near the turbines, there is growing evidence that turbines also affect people through low-frequency emissions. Photographer Larry Lorusso, who lives one mile west of the turbines in Clarksburg, states that he is awoken in the night by the turbines. Michael Fairneny and his wife report adverse health effects at their home on Moores Road, one-half mile from the turbines. The health effects were so severe for Tim Danyliw and Nancy Shea that they abandoned the home they were renovating on Tilda Hill Road.

Serrated edge applications were made to the turbines operating in Vinalhaven, Maine as a beta test. No other turbines with noise violations in Massachusetts have used this technology.

Wisconsin Health Board Puts Onus on Wind Company

October 16, 2014

Enz homeAfter a year-long health study, the Duke Energy wind turbine project in Wisconsin was declared a human health hazard. The  Board of Health of Brown County voted to take the action on October 14, 2014, according to JMKraft writing in Illinois Leaks (Duke Energy’s Shirley Wind Farm Declared Health Hazard).

The decision was based on a report of a year-long study conducted by the Enz family to document infrasound in homes within a radius of 6 miles of the Shirley Wind turbines.

The vote to declare it a Human Health Hazard puts Duke Energy’s Shirley Wind utility on the defensive to prove to the Board they are not the cause of the health complaints documented in the study and could result in a shut down order.

According to the Waubra Foundation, the wording of the motion was:

To declare the Industrial Wind Turbines in the Town of Glenmore, Brown County WI a Human Health Hazard for all people (residents, workers, visitors, and sensitive passersby) who are exposed to Infrasound/Low Frequency Noise and other emissions potentially harmful to human health.

Proximity of Enz home to 6 turbinesFour different acoustical engineering firms performed the study, “A Cooperative Measurement Survey and Analysis of Low Frequency and Infrasound at the Shirley Wind Farm in Brown County, Wisconsin,” which was partially funded by the Wisconsin Public Service Commission.  The technicians recorded readings from several  homes the residents had abandoned (citing turbine emission health impacts).  The results included a statement agreed upon by all four firms – some of whom work for wind turbine developers – that in their opinion, “enough evidence and hypotheses have been given herein to classify LFN and infrasound as a serious issue, possibly affecting the future of the industry.”  WWMA summarized the study in a January 2014 post.

Sarah Laurie, of the Waubra Foundation in Australia, noted earlier this year (“Letter to Slovenia re Known Adverse Health Impacts of Wind Turbine Noise” Aug. 11, 2014) that:

Unlike most other products, where prior product safety is established, the wind industry has never been required to show there are no adverse health effects. … [I]n fact the wind industry are well aware of the serious health problems their products directly cause, and indeed that they have known for thirty years.

There are eight 500-foot turbines in the Shirley Wind project.

Proposed Plymouth Turbines’ Electricity Destined for NIMBY Neighbors

October 13, 2014
Plymouth's Future Generation Wind impact zone

Map credit: Dick Mann. Legend: Green pins mark 4 turbines; yellow pins mark residential streets in Bourne, red pins are in Plymouth, blue are in Wareham.

The towns of Brewster, Marion, Mattapoisett, and Duxbury defeated wind turbine projects in the last few years. Now each town is signing on to power purchase agreements to lower their electric rates, underwriting a turbine project in Plymouth.

This does not sit well with commentators, who posted about the Rich Eldred piece in Wicked Local Cape Cod, “Brewster may purchase wind power” (10/7/14).

“As a resident of Plymouth,” Margaret Burke writes, “it is my request that Brewster not purchase power from Future Generation Wind on the basis of potential harm to the health of Plymouth and Bourne residents.” She notes that the four 476-foot, 2-megawatt Gamesa turbines will be sited within 1300 to 1400 feet of residents. In addition to Plymouth and Bourne, Wareham residents may also be affected, Burke says, with the noise amplified where turbines are close to bodies of water.

I would encourage anyone in these areas who have concerns about their health and well being and that of their families to contact their Boards of Health and other town officials who should have some information on the FGW plan and can hear your concerns, give you feedback and any action plans they may have on your behalf to protect you from health risks associated with living too close to industrial size turbines.

In the comment posted by Mercedes Medford, “Marie Jane” notes “the people of Plymouth will be the surrogate, [they will] carry the burden of the project.” She warns readers about town government actions and potential contracts mentioned in the article:

BEWARE of tight time frames. BEWARE of promises for “the deal of the century.” BEWARE of those who assert that there is no evidence of intense strobing, decline in property value which is proven, of health issues which are being experienced, complex low frequency noise issues which are proven, no acknowledgement of habitat destruction.

According to the Eldred article, Future Generation Wind project in Plymouth is the initiative of Keith Mann, a cranberry farmer who plans to site four 450-foot-tall turbines on 150 acres near Route 25. “The idea is to sell the power to off-takers. The Cape and Vineyard Electric Cooperative wants to be an off-taker and would sell the green energy power to NStar at a higher price and distribute the gains to member communities.”

With the focus of the article on Brewster, Mark J. Cool–who is impacted by one of the Falmouth turbines–finds “it just might be that in Brewster, it’s OK to exploit neighbors in another community if it should save Brewster a few energy budget bucks.”

Scituate’s Turbine Noise Meets Regs–But Only at Reduced Power

August 7, 2014

“Still Life” according to PL photographer Greg Derr

While the Scituate turbine sits idle awaiting a solution from the Chinese manufacturer,* the Board of Health and the Selectmen have been hearing the preliminary report of the noise testing done by Tech Environmental.

“After three nights of testing in five different locations, owners of the 390-foot-tall wind turbine on the Driftway say noise from the machine falls within state regulations,” according to Jessica Trufant, reporting in the Patriot Ledger in Quincy (“Test results show Scituate turbine noise within state regulations” 8/6/14).

In a submission to Wind Wise, resident Dave Dardi said, “The report stated that the turbine was tested on three separate nights and the highest difference found between low ambient and maximum noise output was 7 dBa.” He asked owner Gordon Deane during the BOH meeting for information that he needed for proper evaluation of the data. Mr Deane stated that he didn’t bring that data with him. Mr Dardi pointed out that “the report indicated the turbine was very seldom above 30% power output and never above 60% during the testing periods and in addition the wind was never from the Southwest.”

Video of the Board of Health meeting is posted on YouTube, “Scituate Board of Health Meeting 7-28-2014.” The BOH pointed out that only three of the four tests were completed and voted to ask for the last test to be done while the turbines are running at intermediate speed and the wind direction from the southwest. They also asked why Tech Environmental had not accommodated parallel sampling by an acoustician for a Scituate community group, and were told there had been last-minute changes to the schedule.

*Trufant had earlier reported on the losses mounting from the turbine’s down-time (Software glitch costs owners of Scituate wind turbine $45,000, 7/30/14).

More on Noise Report at Monroe Turbine

August 3, 2014

In her Greenfield Recorder news article, Study: Monroe turbines too noisy (8/1/14), reporter Diane Broncaccio reveals more details on actions taken to address Hoosac Wind’s noise.

Since the letter was written, Iberdrola Renewables has invited 60 neighbors to an information session, to hear landowners’ concerns, give them copies of the sound test results and discuss the planned modifications.

Those modifications include

∎ Install trailing edge serrations (saw-like edges) on the blades to reduce the overall turbine sound.

∎ Develop an operational protocol to address potential turbine noise for when the blades are coated with ice.

∎ Hire an independent engineering service to “study the tonality in more detail.” According to Western Mass. DEP spokeswoman Catherine Skiba, a tonality study is a detailed analysis of where on the turbine the sounds are coming from.

Skiba said the DEP has received 58 complaints since December 2012. [Note: with no Boards of Health in either Monroe or Florida, residents must complain directly to the MADEP].

For more information on the noise report and DEP response, see Hoosac Wind Fails Noise Test.

This is the first case in Massachusetts that Wind Wise is aware of where a “pure tone” has been noted in noise testing. Trailing edge serrations have been tried in Vinalhaven ME with mixed results.

Serrations are added at Vinalhaven.

In a 2012 report, Addressing Wind Farm Noise Concerns, Jim Cummings of the Acoustic Ecology Institute makes sense of conflicting claims about the efficacy of adding serrated edges.

Serrated edges appear to be the most widely studied, with overall noise reductions of 3-8dB being reported (Barrone, 2011). However, many studies have found that these reductions are frequency-dependent, with reductions in low-frequency noise and increases at higher frequencies (over 2kHz). Serrations may be less effective at low or moderate wind speeds; in some situations, this can be when neighbors find turbine noise most audible.

During its first summer in operation, the three Fox Islands Wind turbines on the island of Vinalhaven, ME, were retrofitted with serrated edges as part of an effort to reduce noise impacts on neighbors…. No formal study of the effects has yet been released, though neighbors report that the serrations seemed to moderate the lower-frequency thumping element of the sound, while slightly increasing the overall whooshing aspects, as the studies summarized in Barrone might suggest (personal communications, 2012).


2014 Schematic from European Wind Energy Association, Barcelona

Meanwhile, at Europe’s Wind Energy Association conference in Barcelona this year, Philip Totaro spoke for the industry in noting:

 “A multitude of technologies have been prototyped for low noise but commercial use is limited except in cases where regulations have required it. Technical solutions could be used in combination, but effects have not been comprehensively studied and data is limited. For blade noise, the serrated trailing edge has been the single most influential technology, but others contribute as well. Turbine controls to derate when noise exceeds a threshold are a simple and cheap solution, but come at the expense of energy loss.”


Hoosac Wind Fails Noise Test

July 28, 2014

Ribbon cutting ceremony December 2012

UPDATE 7-31-14:

WAMC Radio reporter Jim Levulis describes the reaction of the MassDEP to Iberdrola’s mitigation plans for the Hoosac project  “Report Finds Hoosac Turbines Out of Compliance.”

Impacted resident Michael Fairneny is not impressed with the plans:

“Forget this mitigation,” Fairneny said. “I would want curtailment…these things shut down. If they’re found to out of compliance then I want something real done about it. I don’t see them ever being in compliance. I mean they are quiet a few days here and there. But the majority of the days when they’re not tested, if I’m not getting pounded the people on Tilda Hill are getting pounded.”

Hoosac Wind is loud. It’s too loud to comply with  Massachusetts noise limits. That’s why an April 28, 2014 letter to the Mass. Department of Environmental Protection offers remedies for the loud sounds. Iberdrola lists the exceedences measured in tests performed in January and February 2014 at monitoring stations at Tilda Hill Road and Moores Road:

• January 9, 2014 measurements were 42.4 dBA average Lmax at Tilda Hill South and 37.5 dBA average Lmax at Moores Road North. Ambient at those locations was 32.2 DBA and 26.7 dBA, respectively.
• February 20, 2014 measurements were 44.8 dBA average Lmax at Tilda Hill South and 44.4 dBA average Lmax at Moores Road North. Ambient at those locations was 27.8 DBA and 27.5 dBA, respectively. These unusual sound levels are attributed to a blade icing condition.

Too bad the company has not informed residents in Florida and Monroe, as it says in its letter it will do:

In addition to these technical modifications, New England Wind [Iberdrola Renewables] will be contacting neighboring residents inviting them to an information session. In that session New England Wind will listen to the concerns of landowners, discuss the sound test results, and detail our technical modifications. In addition, New England Wind will be offering scheduled tours of the site.

This report confirms what several acousticians noted after reviewing the original noise testing results from April 2013. Rob Rand  analysed the initial acoustic report, and Stephen Ambrose illustrated the issues in “Back to the Future II” for a Townsend, Vermont presentation in November 2013.

The large increase in noise above what is a quiet rural background turns this sparsely populated rural area into an industrial zone. But because wind turbines are not regulated like normal industries, the noise continues through the night.

Among numerous issues raised about the initial testing in 2013 were:

  • The turbines were run at a reduced power, which means that the turbines were producing less electricity and emitting lower noise. Iberdrola hired the acoustician (RSG of Vermont) to do the test and therefore was completely aware of the date and time of the testing.  This was true in the April 2013 testing and again in the latest January and February 2014 testing.  Even though the turbines were run at reduced power they still exceeded the Massachusetts noise pollution regulations.
  • Much of the original April 2013 testing was unattended when the MassDEP guidance says the testing should be “attended,” which means the noise is monitored by a person with a sound meter.
  • The test microphones were inappropriately placed near trees, raising the background level.

Independent acousticians also found raw data tables in the April 2013 test report that indicated noise violations, but the company rejected the data on those sampling occasions because they were assumed to be anomalies.

Before the project was ever built, the original modeled noise assessment indicated to acousticians that there would be “widespread complaints” and “strong appeals to stop the noise.” This modeling was performed on a computer in California, without any background noise measurements done in Florida or Monroe MA.

People whose lives have been impacted by the Hoosac project should have a chance to be heard. They will have ideas for mitigation that allow them to have a good night’s sleep.

Will MADEP Regulate or Not?

July 11, 2014

That is the question posed by Firetower Wind in the Turbines over Troubled Waters post and a key question raised by the approach taken by a DEP assistant commissioner, Douglas Fine (quoted by Kathryn Gallerani reporting in “UPDATE: Kingston Independence turbine exceeds state’s noise threshold during study” 7/10/14). The firm hired to test for compliance in Kingston issued an interim report confirming exceedences on two of the dates it tested.

Douglas Fine, assistant commissioner for planning and evaluation, said Wednesday that DEP has offered its assistance to the Board of Health as it sets a course of action in response to the violations of the state air pollution regulation. He did not foresee a conflict July 21.

Fine said DEP delegates authority for determining a course of action, in collaboration with the turbine operator, to the Board of Health.

“Now it’s in the Board of Health’s court to move forward,” he said. “The Board of Health will work with the turbine operator to develop and put in place actions that will eliminate any future exceedences of our noise standard.”

Fine said there are other instances of turbines violating the noise standard and that DEP has shared mitigation options with the Kingston board. He said DEP will also help the board and the turbine operator understand the conditions in place when the standard was exceeded to properly mitigate and prevent recurrences.

Sean and Doreen Reilly, whose family has been among the many households impacted by turbine operations in Kingston, wrote to the town:

As you are well aware we have been requesting and at times begging that you, our town, officials, help us by investigating, and acting, on the Nuisance conditions we have been exposed to by way of both excessive and invasive noise as well as the very disorienting shadow flicker impacts that have enveloped our home, property and neighborhood as a result of the Independence turbine operations.
The next Kingtson Board of Health meeting on July 21, 2014 may begin to address the Reilly’s concerns, but given the DEP’s track record, they may have to wait for a court order to have quiet at night.

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