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Will Serrated Edges Slice Turbine Noise at the Hoosac?

November 2, 2014

UPDATE 12/8/14: According to a letter Michael Fairneny sent to the DEP, serrated edges have not reduced turbine noise:

The new additions DID NOT help the noise coming at us last night…VERY LOUD still …Is there going to be follow up testing to see if this project is under state guidelines? How will you evaluate is further testing is not scheduled…? This project still continues to bother us…and not just when there is icing condititions….but I’m telling you …these serated edges did not diminish the noise comming at us much ….if at all??

Please plan more testing , and not just during icing

Thank You–
Michael Fairneny,, Friends of Florida & Monroe

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.

8 Comments leave one →
  1. December 8, 2014 7:02 pm

    The State of Massachusetts will do anything and say anything to stall anyone with negative information about commercial wind turbines. The state has an agenda to 2000 megawatts of renewable energy by the year 2020 . This is a political objective. The wind turbine victims are collateral damage on the war on fossil fuels. This is an intentional assault on the residents health and property rights around the wind turbines. Fight back ! stop begging these people who have an agenda ! If you know your going to a concentration camp don’t get on the train

  2. November 8, 2014 8:44 am

    In 2011 Ditlev Engel, Chief Executive Officer of Vestas Wind Company was asked why they have done nothing to megawatt turbines so they make less noise.

    Ditlev Engel responded : ” The simple answer is that at the moment it is not technically possible to do so, and it requires time and resources because presently we are at the forefront of what is technically possible for our large wind turbines, and they are the most efficient of all.”

    Ditlev Engel retired shortly after making this statement

  3. Marie Jane permalink
    November 4, 2014 4:05 pm

    Marie Jane says: “The Pentagon logs in strongly against Maryland wind turbine project [as] “An unacceptable risk to the national security” ” (from 10/30/2014).

    Who then will log in strongly against the industrial wind turbine for being “An unacceptable risk to the nation’s health and well being”? Who then will log in and acknowledge that since the first noise complaint the industrial wind turbine was and is, now, nothing more than an imperfect and experimental technology? Who then can allow “GE’s experimental fix for Iberdrola’s out-of-compliance turbines” as remedy? Who will admit there are noise issues that were purposely not researched prior to the siting of all Massachusetts industrial wind turbine projects because the industrial wind turbine agenda came before the people and their safety?

    We know our advocate will not be MADEP. The media? The various Committees, Councils, Commissions appointed to do our thinking for us? The Governor? Our Senators? The President? Perhaps, The Pentagon. If we are intentionally exposing people to harm from within by not shutting down the offending industrial wind turbines, what then is the purpose of national security?

  4. November 4, 2014 7:45 am

    MassDEP sample noise testing has uncovered violations exceeding state limits by more than 5 decibels at every installation that was tested. Any reasonable analysis of the handful of samples indicates that the noise level reaches more than 10 decibels above the state limit for testing on a continuous basis any nights of a year. Ten decibels is twice as loud as the law allows.

    Developers have responded with mitigation plans that interpret the samples very narrowly as worst case by placing small limits on wind speed, wind direction, and midnight to 4:00 AM reflecting the conditions surrounding test periods. The result is that these plans preserve the majority of revenue to the developer, and do little to nothing in providing relief to impacted residents.

    This effort with serrated edges cannot possibly reduce noise levels into compliance, and is just another phony response in a line of phony responses by developers, that should not be accepted by any regulating authority charged to safeguard public health and welfare.

  5. November 3, 2014 7:56 pm

    While the serrated edge may have some impact on audible sounds, I suspect it will have no effect whatsoever on infrasound. That may be coming off the full blade flexing back and forth instead of vortex shedding off the trailing edge of the blade.

  6. Susan permalink
    November 3, 2014 3:37 pm

    Turbines do not have to be noisey to make people sick. The vibration and flashing sunlight cause many of the problems people are having. That is besides the loss of property value and quality of life.

  7. November 2, 2014 9:58 pm

    We are told by MassDEP there is no evidence that Hoosac Wind is out of compliance on the Bakke Mountain side of the project even though the noise continues to disturb us, specially at night. No monitoring is planned by the state for the west side of the project or north with neighbors in Stamford and Readsboro VT having complaints the project is too noisy as well. Meanwhile we are advised by well respected certified acousticians, the only way to be certain the project is in compliance is continuous monitoring and curtailment of the turbines. It simple really, give the neighbors some peace ay night to let us get some rest. They have done that in some other Massachusetts communities, unless profit is more valuable than peoples health?


  1. Noise? What Noise? Tests Designed to Miss the Mark | Smart Meter News

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