In particular, the Sandia team has recently built a Scaled Wind Farm Testing (SWiFT) facility, at which they’ll be studying wake interactions between turbines, and they’ve long been on the forefront of developing new materials and experimental active systems to reduce load strains caused by inflow turbulence.  They’re also leading the development longer blades, which may have important noise implications. Their most exciting forward-looking project is a 5-year effort to re-activate development of vertical axis turbines, with the goal of moving toward 5-10MW scale vertical axis turbines for use offshore (this will be a 10-20 year project, if the first phase shows promise).  Meanwhile, at NREL’s NWTC, lots of research has looked at the pinpointing the sources of sound on turbine blades, as well as advanced modeling of sound propagation in various atmospheric conditions.  Researchers there have quantified the power-production trade-offs caused by wake interactions within wind farms, and are on the leading edge of new technology that might allow individual turbines to monitor incoming air flows and adapt their operations to minimize loads and noise.  All of this research has intrigued me, because of the likely role of wakes and atmospheric turbulence in wind turbine noise levels, and in creating some of the more intrusive sound qualities that neighbors find hard to live with.  My hope was to sit down with these researchers and learn more about their work, as well as draw on their experience to see whether they thought the turbulence factors they study to reduce stress on turbines may indeed also have an effect on the sounds.  

As it turns out, they were also intrigued by such a dialogue, and both labs asked me to present their teams with a seminar on what I’ve been learning about community responses to turbine sound.  Much of what I shared was new to them, and we had some great discussions.  One of the central take-aways from both teams was that very little research has really looked at the acoustic effects of inflow turbulence, and there was universal agreement that this is an important area for future study (as a start, the SWiFT facility will incorporate some acoustic measurements).  Many of them were especially interested in the varying sound quality of turbines, and the ways that this may trigger negative responses among neighbors; there was much speculation about the potential to identify the conditions that create the troublesome knocking, banging, thumping sounds, and perhaps adapt turbine operations to minimize or eliminate them.  As I’ve long found in my interactions with academic and agency researchers, there was an easy openness and curiosity in both rooms, with many questions tossed around, and an excitement about studies they hadn’t seen before. 

Read or download my presentation: The possible role of turbine, wake and shear effects on community response to wind farm noise  (This is the “director’s cut,” including a few slides deleted for length from the final version, along with some additional slides from the REW conference presentation that cover related topics) 

Community Response to Wind Farm Noise: The possible role of turbulence, shear, and wake effects by jimcummings

An article in South Coast Today gives a sense of how this is playing out in Falmouth and Fairhaven, where dozens of families within a half mile or so of turbines have been struggling with noise.  As is often the case, the takeaways are ambiguous.  Two residents near the Fairhaven turbines are quoted, both of whom are reluctantly moving from their homes.  One, who’s been sleeping in his living room because the noise in the bedroom keeps him awake, has found a buyer who’s paying just 7% below his asking price.  The other, whose kids and their mom have already moved away because their 8-year old was having trouble sleeping, had his house on the market at a low-end price, and after “watching buyers come by, look at the turbines and drive away” for several months, he’s now hoping to find renters.  Likewise, a local realtor speaks of a house around a half mile from the turbines that’s been on the market for two years: “They ask about the noise, they ask about the flicker, and then they don’t put in an offer,” she says, noting that the asking price has dropped from $389,000 to $244,900.

In Falmouth, realtors speak about similar troubles finding buyers, with some homes being passed from realtor to realtor as they attempt to sell.  However, the director of Falmouth’s Assessor’s Office says that homes near the turbines have sold at “close to or more than” the assessed value.  At the end of last year, a couple that was one of the closest neighbors to the one privately-owned turbine in Falmouth abandoned the home they designed and built, and started over with a cheap fixer-upper; I have not heard whether it has been sold or not.

Board of Selectmen Chairman Kevin Murphy said that the board will now begin looking at other ways to try to address the long-simmering dispute.  About 40 households have formally filed complaints, representing 15-20% of the homes within about a half mile. Since noise monitoring showed some violations of state noise limits, the two turbines do not run at night, so operate at a loss to the town, though they still produce carbon-free electricity for use at the town’s wastewater treatment plant.

For more on the Falmouth vote, see coverage in the Cape Cod Times and from the AP.
UPDATE, 5/25/13: Three neighbors respond to the vote in this local article.
UPDATE, 6/5/13: Neighbors emphasize that the vote was about funding the previous decision of the Selectmen to take the turbines down (not about whether the turbines should operate), and that the problems will need to be addressed by the incoming Board of Selectmen and/or the Board of Health.  They also say the state should step up with some financial help or forgiveness to lessen the burden on town taxpayers.

Across the bay in Fairhaven, the first results of noise testing were announced at a Board of Health meeting, marking a turning point not unlike one Falmouth encountered about a year ago.  Monitoring by the state Department of Environmental Protection has found that the two turbines in Fairhaven exceeded state noise limits in 5 of the 24 testing periods analyzed so far (more testing in varying wind conditions is ongoing).  All of the violations ranged from 0.7-1.5dB over the limit of 10dB above background ambient conditions.  Two to three decibels is considered the threshold of the human ear being able to hear an audible difference, so these noise levels are not perceptibly louder than sound just below the 10dB threshold; however, we once again see evidence that the 10dB-over-ambient standard is pushing the tolerance of neighbors.  As Fairhaven board of Selectman Chairman Charlie Murphy said, “Before, people didn’t believe the turbines were that loud at night, but now the study shows it,” adding that the results leave him more determined to “give our residents a good night’s sleep.”

As in Falmouth, where violations were also found in only some conditions and just over the limits, dozens of neighbors are complaining of lost sleep and other related health issues.  EPA standards developed in the 1970′s suggested that noise sources are fairly well tolerated when they remain within 5dB of existing ambient levels, and that at 10dB above ambient, “widespread complaints” are likely.  The detailed results from Fairhaven were not released, but the Falmouth report showed all locations exceeding 5dB, and most exceeding 7dB.  Some states still use 5-6dB thresholds, though many have moved to the 10dB used in Massachusetts, or refrain from the difficult task of regulating noise based on ambient conditions.  The Massachusetts measurement protocol has elements that may in part compensate for the larger 10dB threshold, and other elements that could counter that compensation: the standard compares the L90 sound level (quietest times) of ambient conditions with the absolute peak sound levels of noise from the turbines, rather than the average of each, which may somewhat increase the dB difference; however, the use of “slow” five-second time averaging, rather than “fast” one-second samples (closer to how the human ear perceives sound) likely results in lower peak measurements. Again, though, quibbling over exactly how the measurements take place can obscure the larger issue, which is that current standards appear to be insufficient to keep complaints to a minimum.

Since last fall, 105 formal complaints have been filed, by 23 different individuals living near the Sheffield, Lowell, or Georgia Mountain wind projects.  Annette Smith of Vermonters for a Clean Environment is also collecting confidential complaints, some from people who have filed formal complaints, and some from neighbors who have felt it to be futile to complain to the turbine operators and/or state.  

The DPS is hiring a noise expert to analyze the complaints, and comparing them to quarterly noise measurements made near each wind project.  After this analysis, the DPS has three options, and could recommend one or more: enforce standards if they find violations, create a more effective system for operators to respond to complaints, or ask the PSB to change the noise standards if necessary.

See this recent local news article for more, including details of a recent bad night for neighbor Kevin McGrath, whose house is pictured above.

The study ruled out other common causes of cetacean strandings, including foraging for fish in shallows, attack by orcas, illness, algal toxins, recreational boats, and earthquakes.  However, the researchers also could not identify a likely trigger among the Naval activities taking place on the morning of the strandings or the day preceding the discovery of the struggling animals.  Press reports at the time suggested that locals heard some large explosions on the day before and day of the strandings, though the researchers did not find records to indicate such activity. Mid-frequency sonar transmissions ended four days earlier; that or other ongoing activity is thought to have driven the dolphins into the bay, with unknown further disruptions triggering the fatal strandings early on the 9th.  According to lead author Paul Jepson, “Eyewitnesses described their behaviour as swimming continuously in tight circles, being vocal, fluke-slapping, leaning sideways, and often with one or more individuals attempting to strand.” 

The lack of a clear cause for the final stranding event during a relative pause in Naval activity on the day before the early-morning discovery of the floundering dolphins adds a familiar ambiguity to the situation.  A Naval spokesman noted that they disagreed with the report’s conclusion and stressed their decades of similar exercises in the area without mass strandings, while conservation groups including the NRDC and the UK-based Whale and Dolphin Conservation called for exercises to be redesigned. While cetaceans can often move away from unwanted noise, it’s long been known that strandings can occur when animals become trapped in areas with no escape route, such as apparently happened here.

Despite Naval denials of responsibility, this event did spur some changes that have led to later exercises being temporarily suspended when dolphins appeared on the verge of being trapped in a similar situation.  As detailed in the new study:

Following this MSE (Mass Stranding Event) and recommendations from the organisations involved in the rescue of dolphins in the MSE, the UK Ministry of Defence initiated the Marine Underwater Sound Stakeholders Forum in the UK to regularly meet with all interested stakeholders (scientists, other Government Departments like Defra and a range of non-Governmental organisations) to discuss these issues in some detail. A direct line of communication was also established after the Falmouth MSE to facilitate rapid exchange of information between cetacean strandings/sightings organisations and Royal Navy Naval Command Headquarters to report groups of pelagic cetaceans seen unusually close to shore and potentially at increased risk of stranding. This was used to report a near-MSE of over 20 common dolphins in the Fal estuary in April 2009 that was seen 15 minutes after RN sonar trials were initiated in the region. The RN immediately modified the naval exercise (including use of active sonars) until the group of dolphins had returned to open sea several hours later. The need to alter training excercises due to the presence of dolphins has not subsequently occurred in this region.

According to the authors, “Such continual improvement of mitigation strategies by the military themselves is probably the best way to limit future environmental impacts of naval activities, including cetacean MSEs.”

Ironically, considering the growing concern over the impacts of human noise on whales worldwide, early settlers in Wellington complained that whales in the harbor there kept them awake at night!  How the times have changed….

UPDATE, 4/11/13: On the final night of Town Meeting, a 90 minute discussion resulted in a measure that will put the $100,000 question before the full town in the May 21 election, rather than authorizing that money to begin to be spent immediately; in addition, this money may only be spent if the town as a whole votes to dismantle the turbines. At its April 11 meeting, the Board of Selectmen agreed to put a binding referendum on the May 21 ballot, approving additional tax levies to cover deconstruction of the turbines.  Coverage of this discussion and vote is here.  Also, the town meeting in nearby Scituate voted down a non-binding citizens proposal to urge revocation of the local permits for a single turbine that has also spurred complaints from its nearby neighbors; coverage here and here.

Last week, the Massachusetts Clean Energy Center said that it would consider forgiving the town $2 million in Renewable Energy Credits already paid and due to be delivered in the future, but only if the turbines were not dismantled, and the town did not impose any noise restrictions more stringent than state regulations.  This represents a small part of the estimated $12-15 million total necessary for decommissioning; over $10 million of this is outstanding loans, which the town hopes will be reduced via debt forgiveness by the state for one turbine, and possible state financial assistance for the other.  In the recent vote, though, the Town Meeting was considering a measures that would authorize the town to spend up to $14 million, since state support is uncertain.  The proposed borrowing would raise average property taxes by $48 per year, or a total per household of about $800.

The two town-owned turbines had been projected to create a net revenue of several hundred thousand dollars a year, in electricity saved at the town Wastewater Treatment Plant, electricity sold on the open market, and Renewable Energy Credits.  However, for the past year, since state DEP noise monitoring found noise levels exceeding state limits in the nearby neighborhood at night, the turbines have been shut down at night, and so operating at a deficit of about $100,000 a year due to the significantly diminished output. This recent article in Cape Cod Times provides a history of the turbine project in Falmouth, the emergence of impacts among neighbors, and the town’s efforts to decide how to respond.

At the town meeting, local green energy advocates urged a “no” vote, saying that it would be more  cost-effective to buy houses from those most upset with the turbine noise, while two Selectmen spoke in favor of the measure, because of the current annual losses, the need to heal the split in the town, and the fact that a town Wind Turbine Options Process group that met for several months came to the conclusion that, among several final options, decommissioning was the best choice.  

If the May 21 town-wide vote agrees to dismantle the turbines, the matter of borrowing funds to complete that process will return to the Town Meeting at another of its biannual sessions.  Meanwhile, town officials will continue to develop plans to navigate the “considerable complexity” of arranging all the necessary financing, contract revisions, and special legislation that will be needed to complete the process.

The Tribunal notes that it found the evidence of health effects to be both consistent and convincing, though both the extent of the problem and the cause were far less clear. It also notes that many (though not all) of the health effects referred to in the literature occurred at distances of less than 2km, which is the statutory setback in effect in Victoria.  Getting more clarity on how common effects are beyond that distance appears to be at the heart of the Tribunal’s decision to postpone a decision for six months:

The Tribunal considers that the issue of health and wellbeing raises two distinct questions. The first question is whether there is a causal link between sound pressure emissions from wind turbines and adverse health effects on nearby residents. The link may be physiological or psychological. However, given that the respondents expressly disavow that the impact is psychological and that the so-called “nocebo effect” lacks any empirical basis, the inquiry in this case must be as to whether there is a physiological cause. In this regard Mr Cooper hypothesised that wind turbines may emit a particular low frequency “signature” that gives rise to the problem.

One difficulty facing the satisfactory resolution of this question is that there appears to be no overlap of expertise between the acousticians and the health experts. The acousticians can measure the noise but are unable to say what effect it has on human health. The health experts can identify the health issues but are unable to connect those issues with particular levels of noise or sound pressure. It is this that creates the need for interdisciplinary studies.

If the first question produces an affirmative answer, the second and equally important question is what is the incidence of health problems amongst the nearby residential population, and how does that incidence vary or attenuate with distance from the wind turbines. Obviously the problem must be given greater weight by decision makers if 50 per cent of the population surrounding a wind farm is affected rather than 5 per cent.

The full statement linked above (which also has a long section on noise annoyance and sound limits), and an excerpt containing the section on health and well-being, paint a pretty solid and concise picture of the Tribunal’s quandary.  The South Australian EPA is conducting a study around the Waterloo wind farm in the next couple of months that may help answer at least some of the questions, and the Tribunal is eagerly awaiting these results.  It has also invited both sides in the dispute to submit further information that contribute some of that interdisciplinary insight mentioned above.  

This post, for example, notes that “mischaracterizations are coming out from all around,” and encourages residents to beware of any new surveys that appear to be asking questions about one’s overall quality of life or any annoyances other than wind farms.  The concern seems to be that general quality of life or attitudinal/psychological questions can contribute to the sorts of extreme claims that have filled the press recently, suggesting that “nocebo” type effects are the primary cause of health symptoms and annoyance complaints.  A detailed comment in the post includes a letter sent by one resident who returned a recent University of Waterloo survey without completing it, noting that “questions appear to be constructed in a manner that can be manipulated to achieve any desired result.” Here’s another site that similarly characterizes the UW survey as a political and wind industry sham.

All of these surveys, in order to be representative, need to have responses from a representative sample of both people being bothered and those who are not bothered.  Here, as in some previous research local efforts, distrust has grown to the point that those most affected may not participate.  While for many of those being kept awake or otherwise affected by nearby turbines, the question at hand appears very simple—the turbines are the issue, and they affect me—a useful survey will need to do more than simply ask about turbine health effects.  There are a lot of contributing factors, and it can be useful to consider many of them.  

While such surveys may be subject to misleading interpretations at times, the fact is that surveys and studies are always interpreted differently by those on opposite sides of the issue—where one side sees proof of their supposition, the other sees vague results, poorly designed data collection, or exaggerated significance.  It’s clear that both the idea that turbine noise has nothing to do with the problems being reported, and the idea that turbine noise is inevitably harmful for those living nearby, are overstating what studies and surveys have found. Still, such disputed studies provide raw data that can help quantify the extent of issues and become valuable sources of clear information for those on both sides of the issue, and especially for local decision-makers. 

In particular, if those most affected decline to participate in the Ontario studies, these surveys will come to conclusions that far fewer people are bothered by noise than are, in fact, affected.  This can’t be good for anyone.  Rather than fear the possible misinterpretations, it would be better to help assure that these surveys obtain results that reflect the actual extent of the noise problem.

UPDATE, 4/15/13: Some area residents are telling the University of Waterloo researchers that it’s already too late to measure pre-construction stress and other health markers.  This study is meant to provide a “before and after” picture of local sleep and overall well-being.  But, according to  an article in Niagara This Week, residents question whether it will do so:

“You’re not starting in the right place,” resident Debbie Hughes told Bigelow, during the public comment portion of Monday’s meeting. “We are already affected by the turbines. Our stress is already high.”

A dozen residents, all opposing wind turbines, shared similar messages. “It’s too late, two years too late,” said Helen Kzan, wearing an NRWC receptor 2418 bib. “I’ve been to the doctor. They told me to move.  My stress level has skyrocketed. My physician told me my stress will kill me before the wind turbines.”

While what the locals are calling “the pre-stress level” is likely already be elevated, it would still seem likely that the study could identify any trends in sleep disruption and more widespread stress that may be caused by the noise of the turbines once they’re built (at least, if those affected choose to respond to surveys). The whole situation highlights the ambiguities that exist in trying to determine the cause of any health effects that do occur.

Except in winter.  The groundbreaking Travel Management Rule specifically exempted snowmobiles from being subject to the limits contained in each forest’s local Travel Management Plan.  The reasoning was that many of the damaging aspects of unfettered ORV use were less relevant in winter; in particular, damage to vegetation and streambeds, and all the related risks of increased erosion.  These impacts are indeed significantly less in winter, though some soil compaction can occur beneath snowmobile trails over meadows.

But one key impact from motorized use can actually be worse in winter: the noise footprint of the vehicles.  Thanks to better sound transmission in cool air and across frozen, leafless landscapes, the sounds of snowmobiles often travel much further than the sounds of ATVs and dirt bikes in summer. This can clearly impact other forms of recreation, as well as disturbing animals who are sensitive to noise intrusions. In Idaho, lovers of “quiet recreation” worked hard to get snowmobiles included in national and regional travel planning, and when they failed, the national Winter Wildlands Alliance took the question to the courts.

This week, a Federal Judge in Boise agreed that the exclusion of snowmobiles from an otherwise comprehensive approach to travel management planning was “arbitrary and capricious” and “contrary to law,” ordering the Forest Service to revise the 2005 Travel Management Rule within 180 days to include snowmobile management.  According to the AP:

Mark Menlove, executive director with the Winter Wildlands Alliance, said the decision was a monumental victory for backcountry skiers and other winter recreationists seeking a peaceful experience in the woods.  The group’s goal is to not shut down snowmobiles in national forests, but force the agency to designate specific boundaries that carve out distinct areas for those who want to explore on powered sleds and those preferring skis, snowshoes and hiking boots.

“Many of our members use snowmobiles more and more to get to certain places, so we’re not in any way asking the forest service to ban them,” Menlove told The Associated Press on Monday. “But we are asking for some balance there, where our constituents can go and find peace and powder snow in the backcountry.”

While this ruling applies only to National Forests in Idaho, it may lead to similar reviews and expansion of travel management planning nationwide.