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Who Said an Industrial Wind Turbine Is No Louder than Your Refrigerator?  

Author:  | Noise, U.S., Wisconsin

Is Your Refrigerator Running? Better catch it – and see if it makes as much noise as a 40 story tall industrial wind turbine.

In anticipation of posting testimony given at the public hearing for the town of Union’s wind ordinance on May 29, here is a document submitted by a member of the Town of Union’s Large Wind Turbine Citizens Study Committee regarding a statement widely used by wind developers comparing the noise an industrial wind turbine to the noise of a refrigerator. The committee member tried to track down the source of this quote and submitted these results which are now part of the public record. It reads:

Today, an operating wind farm at a distance of 750 to 1,000 feet is no noisier than a kitchen refrigerator or a moderately quiet room.

There’s a statement out there that has been used by people involved in the wind industry, most commonly cited on the American Wind Energy Association site that goes like this: “Today, an operating wind farm at a distance of 750 to 1,000 feet is no noisier than a kitchen refrigerator or a moderately quiet room.”

A similar statement appeared in the National Wind Permitting and Siting Guide 2002. So I wrote the NWCC and asked them if they knew the source since there wasn’t a footnote listed with a supporting reference.

They didn’t know.

AWEA referenced the National Renewable Energy Lab as the source, so I wrote them.

Even though they were very helpful and put me in touch with their staff noise authority, they could not come up with the author of that statement, however they did copy pages from books that their noise authority called the quintessential references on wind energy and noise.

So, then I Googled it. I typed in the refrigerator statement in question and came up with these statements from the American Wind Energy Association.

Author Tom Gray, AWEA:“Today, an operating wind farm at a distance of 200 meters (658 ft.) is no noisier than a refrigerator “.

Author Tom Gray: “Wind turbine noise (at 200 m) is as loud as your refrigerator heard from the living room”.

Author Tom Gray, AWEA . “Today, an operating wind farm at a distance of 300 meters (987 feet) is no noisier than a kitchen refrigerator or a moderately quiet room”.

Author Tom Gray, AWEA. “Today, an operating wind farm at a distance of 350 meters (1151.5 feet) is no noisier than a kitchen refrigerator or a moderately quiet room”, to:

Author Tom Gray, AWEA. “Today, an operating wind farm at a distance of a quarter of a mile is no noisier than a kitchen refrigerator or a moderately quiet room”

and finally:

Author Tom Gray, AWEA. “Objective measurements with sound meters show that a wind turbine, at a distance of 500 to 750 meters, (1645 to 2467 feet) is no noisier than a kitchen refrigerator or a moderately quiet room. If you doubt this statement, we invite you to visit a wind farm and see for yourself”.

From the very beginning, our committee was determined to take on the challenge of supporting our draft ordinance setback recommendations with references from the wind industry. It may just be an assumption, but we understand if the information comes from the sources that [wind developer] Ecoenergy listed as acceptable, that would then be deemed as a credible source.

Setbacks

AWEA, 1645 to 2467 feet (approx. 1/2 mile) for noise.

NWCC Permitting and Siting Guide 1998, and appropriate distance may be 1000 feet to ½ mile or more for noise.

AWEA Recommended book to buy: Wind Energy Handbook by Tony Burton. A minimum spacing from a dwelling for shadow flicker 10 rotor diameters (1/2 mile). Also added that a spacing of this magnitude is likely to be required in any event by noise constraints…

To note if there is an issue whether or not we are in an area susceptible to shadow flicker, there is Harvest the Wind: A Wind Energy Handbook for Illinois. Even though it wasn’t on the preferred list, Lisa Daniels from Windustry and Wes Slaymaker from Ecoenergy were authors so I thought it would be acceptable. “Shadow flicker may be more of a problem in northern Europe, Canada, and the upper Midwest than elsewhere…”

I looked up upper Midwest on Wikipedia, and Wisconsin is included in the upper Midwest.

Windustry, Best Practices and Policy Recommendations. “Turbines should be sited no less than 5 times their rotor diameter (1320 feet) from property lines unless written permission is given by the neighbor. This recommendation is designed to protect wind rights of all landowners and minimize the impact of wind turbines on neighbors.

Noise Limits:

NREL: National Energy Renewable Laboratory which is part of the US Dept of Energy, said as mentioned earlier that the quintessential reference for wind turbine noise is Wagner 1996 , “Wind Turbine Noise”, and Manwell’s “Wind Energy Explained”.

These pages that they sent me from these books referenced these items in the draft ordinance:

  • Germany night time rural noise limit 35 dBA, outdoors.
  • A fixed noise limit alone will not eliminate noise complaints.
  • A change in the sound level of 5 dB will over ambient noise will typically result in noticeable community response.
  • Tonal noise penalty.
  • Distance attenuation and sound propagation.
  • Differences in noise from day and from night.
  • Frequency of noise and dBC filter.
  • Aerodynamic Noise.
  • Multiple wind turbines. 2 at equal value increases the noise level by 3 dB.
  • Weather effects and noise.
  • Downwind noise.

In closing, finally some key points from the new AWEA Wind Siting Guide 2008:

“The studies required in the permitting process should be science-based and tailored to the specific site. Each wind developer has a responsibility to further the reputation of the industry by providing appropriate and sound oversight of the regulatory process. (1-3)”

Shadow Flicker

“A wind turbine’s shadow flicker impact area does not generally extend beyond 2 kilometers ( 1 ¼ miles) and high-impact durations (? 200 hours per year) are generally located within approximately 300 meters(987 feet) of the turbine. …The potential for shadow flicker has been raised as a visual issue by close neighbors of wind farm projects. (5-33)”

Sound

“Most states and localities establish noise limits at property boundaries based on specific sound pressure levels measured in decibels. (5-35)”

“The relative increase in sound from the project may be as important, or more important, than the absolute sound levels of the project itself. (5-36)”

Ice Shedding

“It has also been observed that the rotor ice can break off, and if the rotor is moving, can be cast some distance. (5-47)”

Please submit to Public Record.

Thank You.

MORE TESTIMONY: WHAT’S NOISE GOT TO DO WITH IT?

Q: What is Aerodynamic modulation? What is distance attenuation? How do dB’s add up? Three Turbines producing 45db equal what total dB? Do wood frame walls attenuate low frequency and high frequency noise equally?

These questions are part of the following document which was also submitted to the town of Union’s Plan Commission members by a member of the town of Union’s Large Wind Turbine Study Committee who has spent the last year researching the subject of noise from industrial wind turbines.
Here is his testimony:

Public hearing comments

Survey

Government officials have an intrinsic responsibility to protect the citizens. State statute 66.0401 restricted the wind committee research and recommendations to health and safety issues. Now the Plan commission members are faced with the same restriction. The supposed popularity of wind turbines should not carry any weight in making a decision concerning health and safety.

Noise

Noise is subjective. The town government and local residents should decide how much noise we should be subjected to during the nighttime hours. Not a wind developer. The developer has never offered anything less than 45dB which will be 15 to 20 times louder than we have now. Sleep deprivation is a well established health risk. It leads to a multitude of other health related issues.

The World Health Organization has found that sound levels during nighttime and late evening hours should be less than 30 dBA during sleeping periods to protect children’s health.

Atmospheric conditions can wreak havoc with nice clean sound propagation models, especially at night. And, as turbines get bigger, their noise can be deceptively hard to predict. Temperature inversions, wind layers, and other atmospheric effects can lead to surprisingly distant sound impacts. The noise levels can easily be 15 dB louder than predicted.

In some cases, low-frequency noise can become an issue with wind turbines. It is a component of a broadband noise field generated by spinning turbine blades. Low-frequency noise travels greater distances with less loss of intensity than higher-frequency sound.

Noise standards can very easily fail to protect nearby residents from disruptive levels of noise. When standards are exceeded the task of enforcement will quickly out distance the ability of local government and law enforcement. It is crucial that everyone involved (industry, government, residents) resists the easy temptation of relying on “paper” assurances that wind turbines will not create acoustic impacts.

With continual incorporation of best technology and best practices in siting, wind energy need not be stymied by noise issues. However, with noise impacts gaining more public credence, it is clear that the current boom in wind farm development could well backfire, for both the industry and a clean energy future, if the current generation turbines are sited too close to residences.

Noise impacts are not necessarily deal-killers for wind energy, as long as developers are honest about what is likely to be heard and continue to work diligently to investigate the aspects of wind turbine noise that are still not fully understood.

Better to be conservative, accepting the fact that even occasional atmospheric effects should be factored in to siting decisions today, so as to build a reservoir of good will, rather than a rising tide of complaints.

Questions
What is aerodynamic modulation?
What is distance attenuation?
How do dB’s add up? Three turbines producing 45dB each equals what total dB?
Do wood frame walls attenuate low frequency and high frequency noise equally?

If you are unable to answer these questions you need to rely on and trust that the wind committee has researched these issues. The recommendations of the wind committee for setbacks and noise limits should be considered the minimum to protect public health and safety.

Paul Cheverie, chairman of the Eastern Kings Community Council (Prince Edward Island, Canada) said. “There are no rules and regulations on windmills,” “The more we get into it, the more we realize we jumped the gun.”

[end of testimony]

To download the Town of Union’s Large Wind Turbines Study Committee’s Final Report which includes all supporting documentation for the wind ordinance, click here.

To watch video and hear audio of the May 29th Town of Union public hearing, visit the Evansville Observer by clicking here.

To watch a Milwaukee Channel 6 news segment which shows the trouble with living too close to industrial wind turbines, click here.

If you’d like us to send you a free DVD copy of this news segment contact us by clicking here or by writing us at Better Plan, Rock County; PO Box 393; Footville, WI 53537. We’ll be glad to send you a copy right away.

Friday, May 30, 2008 at 01:15PM
The BPRC Research Nerd

This article is the work of the author(s) indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.

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