As regular readers will know, the National Park Service completed an epic planning process earlier this year when it released proposed rules governing air tours at Grand Canyon National Park.  After over two decades of discussion, including a failed attempt at coming to a consensus decision with all parties a few years back, NPS planners came up with an approach that was generally well-balanced.  It allows airplanes and helicopters to remain a strong presence in the park, with 8000 more annual flights being allowed than have been occuring in recent years, and half the park still hearing aircraft throughout most of the day.  On the plus side of the ledger for quiet recreation is a groundbreaking no-fly period for an hour after sunrise and an hour before sunset, a window of peace and quiet that will transform the back-country experience for the entire park.  And, flight corridors in two popular back-country areas will alternate seasonally, so there is a time of year in each when it will be noticably more serene.

Nevertheless, the air tour industry claims the plan will put them out of business; it’s not at all clear how this could be, given the greater numbers of flights.  I wonder whether the sunset period is especially popular for flights; if so, this could be a bitter pill for air tour operators to swallow.  Yet it’s hard to deny that this is a time of day when river runners and hikers will find their experience immeasurably improved when birds, wind, and water are the dominant features of the evening soundscape.

Heeding the air tour griping, four Congressmen, two from Arizona and two from Nevada, have added an amendment to a Department of the Interior appropriations bill that would strip all funding for implementation of the rule.  Earlier, the region’s two most powerful Senators, John McCain and Harry Reid, signed a letter opposing the plan, and McCain also attempted (and failed) to push through an amendment blocking it.  For more on the current amendements, see this editorial in the Arizona Republic and this post that details objections from other Arizona representatives and the National Parks Conservation Association.

A couple of articles in this month’s Wind Power Engineering caught my eye.  What follows is more speculative than what you normally find on AEInews, but with that in mind, I encourage you to check the articles out yourself.

Both articles address basic issues regarding wind turbines: the wakes they create downwind, and normal wear and tear of turbine blades.  Neither one considers noise impacts at all, and I don’t have the engineering background that might allow me to make truly informed extrapolations.  But both certainly seem to be worth bearing in mind as project planners and managers address possible noise issues.  The main thing I wonder is whether either of these factors might make turbines slightly louder than expected, or than modeled under more ideal assumptions.

The first article covers a topic we’ve covered here at AEInews before: ongoing research into the turbulent wakes that stretch out downwind from wind turbines:

Today’s massive wind turbines reach into a complicated part of the atmosphere, Julie Lundquist expalins. “If we can understand how gusts and rapid changes in wind direction affect turbine operations and how turbine wakes behave, we can improve design standards, increase efficiency, and reduce the cost of energy.”

The second article focuses on routine maintenance of wind turbine blades, and explains some of the normal wear and tear that needs to be attended to.  It seems likely that at least some blade imperfections would add extra noise, which is of course largely caused by the airflow coming off the blades.

Traditionally, less attention has been paid to the repair and upkeep of turbine blades versus other components. Instead, preventive maintenance programs have focused on the internal mechanics of turbines due to the predictability of their maintenance requirements. Typical preventive maintenance plans for internal components fall into 3, 6, and 12-month work schedules. By nature, blade repairs are more difficult to plan. Blade damage can arise in manufacturing, transportation, and tower construction and erection. However, maintenance issues more often occur in the field from leading-edge erosion, weather, and other factors. A lack of predictability and historical data complicates preventive maintenance for blades.

Commercial turbines can have tip speeds of over 200 miles per hour. At these speeds, rain drops can take on the impact of small stones, and blowing sand has the erosion power of a plasma cutter. Studies have shown blade roughness and accumulated debris on the blades can reduce wind turbine performance by 5 to 30%. Blades that aren’t working efficiently can also create vibration that contributes to gearbox failures.

Joshua Crayton, a contractor who provides blade maintenance services, notes that regular inspections are especially important in windy seasons and following lightning storms. “Operators and owners are inheriting their wind farm assets and the responsibility of maintaining blades that are no longer covered by the (manufacturer) warranty,” he says. “Like any business, wind farm owners and operators typically run a lean staff and may not have an experienced maintenance technician in-house. Partnering with a service company can help them design a long-term, post warranty, preventive maintenance plan.”According to Crayton, a maintenance plan should be initiated before the warranty period expires. “A thorough internal and external blade inspection should be scheduled in the warranty period,” he says. “Once owners and operators take over care of a wind farm, these inspections should take place every two years. Personnel can conduct simple ground inspections while on-site, but there is no substitution for a close, visual examination performed uptower.”

PLUS: Two other short articles may also be of interest: one on design concepts for a 20MW turbine (today’s big ones are 2MW), and the other a very positive development, a 36MW battery designed to stablize output to the grid from wind farms.

This post is an AEI lay summary of the following paper:

McCarthy, Moretti, Thomas, DiMarzio, Morrisey, Jarvis, Ward, Izzi, Dilley.  Changes in spatial and temporal distribution and vocal behavior of Blainville’s beaked whales (Mesoplodon densirostris) during multiship exercises with mid-frequency sonar.  Marine Mammal Science, Volume 27, Issue 3, July 2011.

For the past several years, ongoing research at the US Navy’s AUTEC training range in the Bahamas has been providing data that confirms what many had long suspected: that beaked whales move away from active sonar transmissions.  A recent paper published in Marine Mammal Science quantifies the changes in more detail than has occurred before.

Using recordings from the permanently-installed hydrophones lining the seafloor of AUTEC, the researchers charted the foraging vocalizations of Blainville’s beaked whales before, during, and after extended Naval training exercises (85 hours in 2007, 65 hours in 2008). In 2007, when activity was high prior to the exercises, animals returned to the range in somewhat lower numbers within 24 hours:

in 2008, when there was less activity prior to the exercises, very few animals returned in the first three days, but many were there shortly thereafter:

Among animals who continued foraging while sonars were nearby, they appeared to tolerate received levels ranging from 101 to 157db, which correlate to sonar transmisisons from ships 2-28km away.  A key question considered is whether the animals left the area, ceased vocalizing, or were masked by the exercise sounds. Because of the way that vocalizations increased first around the edges of the range, moving toward the center, the researchers are confident that the animals predominantly left the range; the decreased levels of vocalizations even around the edges imply that most animals moved more than 6km from the range (the limit of confidently knowing they’ll be heard by hydrophones along the perimeter).

The paper concludes by summarizing related ongoing research, including studies that aim to determine whether decreased foraging, especially directly after exercises, is due to fewer beaked whales in the area, or less preay (ie, was the prey moved off the range by the exercise activity and noise?).  The authors also note many as-yet unanswered questions that are triggered by their results, including whether the displaced animals continue feeding elsewhere during their absence from the range, and whether this particular population is more habituated to the sonar sounds, so that they either tolerate it better or are less apt to exhibit the presumably more dangerous behavioral responses that lead to strandings.

The UK wind industry is scrambling to respond to a High Court ruling that affirmed the legaltiy of conditions placed on the Den Brook wind farm near Devon, limiting ampltude modulation of wind turbine noise to a level that could be very hard to comply with.  After years of pooh-poohing the reports of neighbors who said that the pulsing quality of the turbine noise made it especially hard to live with, including a much-criticized study a few years back that found nearly no AM at UK wind farms, Renewable UK (formerly the British Wind Energy Association) is fast-tracking a far-reaching study of AM, which they hope to complete in just seven months.

The new study, funded by Renewable UK (a trade organization of wind industry companies), aims to develop better models for predicting AM, including assessment of the effects of high turbulance and closely spaced turbines, as well as noise predictions both nearby and at a distance.  In addition, they aim to develop a listening test that could inform a possible penalty-assessment approach to dealing with AM noise when it does occur; such an approach, common in many regulations, forces the overall noise level to be lower when AM is present.

After years of claimng there is no need to assess or regulate AM, it appears that the industry has now found itself sufferering the consequences of denying the problem.  Instead of working to create regulations that take the issue seriously (whether or not it is common), the industry is now vulnerable to being out of compliance when AM does occur.

The recent ruling unfolded along just these lines.  The wind developer claimed noise would be inaudible or at least not problematic, while local resident Mike Hulme was unconvinced and wanted to be sure that if AM did occur, there would be consequences for the wind farm.  His acoustical consultant Mike Stigwood told the Noise Bulletin: “I devised an excess amplitude modulation condition based on my findings and measurements at other wind farms that was worded simply and made an exceedence a breach. It was a simple stand-alone condition.” In an earlier round of litigation on these conditions, the developers proposd a penalty approach to dealing with non-compliance (thus seemingly implying that AM could occur), but the Inspector who wrote the rules did not incorporate their proposal, because he felt the proposal lacked necessary detail to apply effectively.

While the High Court ruling denied the appeal’s goal of stopping the Den Brook wind farm from proceeding, it affirmed the validity of the AM condition and stressed that the wind farm must comply with the rules as written, which are very stingent: whenever sound levels are over 28dB, turbine noise (measured in very short time intervals) can’t vary by more than 3dB.  To avoid penalizing random momentary fluctuations, the AM provision applies only when this pulsing of sound occurs more than five times in two minutes, and for at least six minutes in any hour.

While ruling that the condition as written was valid, the Court said that there was no provision in the ordinance that would allow any sort of penalty or other way of dealing with non-compliance with the AM limit, short of shutting down or changing operations so as to remove the pulsing sound. It’s likely that this High Court ruling will provide precedent and justification for the development of ordinances that do address Amplitude Modulation as a particular quality of wind turbine sound, and that future ordinances will be developed with a penalty scheme to minimize the negative effects of this pulsing quality of wind turbines, by requiring them to be quieter when AM is present; in practice, this is likely to mean that wind farms will need to be built a bit farther from homes, so that their noise is quieter all the time, leaving room for AM factor to be added without breaking the noise limits.

For more, see this article in The Environmentalist, a leading UK magazine, or read the High Court ruling here. Also fo note, the June 2011 edition of Noise Bulletin includes an in-depth article on the court case, along with a good summary of the Wind Turbine Noise 2011 conference, including a sidebar introducing the industry-funded AM research program; Noise Bulletin is not viewable online, but free sample issues and trial subscriptions are available on their website.

An Ontario Environmental Review Tribunal has ruled that the Kent Breeze Wind Farm can be built, denying an appeal by the a local resident and a community group that challenged the wind farm’s permits, largely on the basis of health effects that it may cause among nearby residents. Since Kent Breeze is the first wind farm to be approved under Ontario’s new green energy development rules, this was seen as a key to near-term wind development in the province.

The Tribunal’s 223-page ruling provides a fascinating, in-depth look at the state of current wind farm science and policy; many pages are devoted to the testimony of each of the witnesses, which included well-known researchers with a wide range of viewpoints, including Rick James, Geoff Levanthall, Christopher Hanning, Robert Colby, and many others.  I highly recommend that anyone interested in these issues download the full report and give it a look.

An article in the Windsor Star includes predictable responses from all concerned. “We are pleased with the decision of the tribunal,” said Jennifer Lomas, spokesperson for Suncor, the developer. “In terms of the alleged health concerns, we are committed to understanding the interaction of our operations and the environment. We meet all operating standards for these projects, this includes strict compliance to regulatory (rules).” Meanwhile, John Laforet, head of Wind Concerns Ontario, stressed that “(The tribunal) said there were risks and uncertainties. We aren’t debating whether there is a problem or not, but whether there is responsible development. We want believable studies and setbacks based on the outcomes of those studies…We are hopeful this ruling, while it’s a battle lost, it’s a step toward winning the war provincewide.”

Indeed, the Tribunal stressed in its ruling that “It is hoped that the legitimate debates surrounding the effects of turbines will spawn further independent research to the point that some of the challenges posed in this Hearing will be reduced over time.”   Futher, “The Tribunal accepts that indirect (health) effects are a complex matter and that there is no reason to ignore serious effects that have a psychological component.” This is a stark contrast to the CanWEA/AWEA health effects study, which focused nearly solely on direct health impacts, dismissed indirect effects triggered by annoyance, stress, or sleep disruption as insignificant or subjective, and concluded that there was scant reason to look deeper at the issue.

Click on through below the fold for AEI’s in-depth summation of the key points made in the full ruling.

Read the rest of this entry »

A very cool research program is underway in the Bahamas this summer.  In an attempt to understand whether exposure to ocean noise sources creates stress in whales, a team from the New England Aquarium is collecting fecal matter for stress hormone testing (the photo at left shows Roz Rolland surfacing after a successful collection dive).  Increased stress can lead to many secondary issues for any animal, including health impacts and reduced reproductive success. A series of blog posts from their two weeks on site is a fun read.  The work is continuing in the Bahamas, though this team has headed home.

Here also is an MSNBC article on the research.

The first field results from a Caltech research team led by John Dabiri have been published, and they suggest that Dabiri’s new approach to wind generation may be just what rural communities have been hoping for: the ability to proceed with widespread wind energy development without changing the character of local landscapes and soundscapes.

Dabiri’s team is looking at wind energy efficiency from an entirely new perspective: rather than designing individual turbines to capture as much of the wind energy passing through their blades as possible, they’re looking to capture as much of the wind energy in the projects footprint as possible.  Instead of the 300-400 foot 3-armed turbines we’re used to, the Caltech team is optimizing a tightly-packed array of 30-foot spinning vertical tubes (vertical-axis turbines) that look more like egg beaters or old-fashioned lawnmowers turned on end.  Inspired by fish schooling, the turbines use the air flow from one another to optimize energy capture and efficiency; by contrast, giant horizontal-axis turbines (the standard design we’re familiar with) need to be very far apart so that their turbulent wakes don’t interfere with each other.

In the first field season, last summer, a tiny test plot of just six turbines was arrayed in various configurations, so the  team could find what works best.  This summer, 24 turbines are being used in the second year of field tests.  Last summer’s results, while clearly preliminary, are exciting: the array produced 21-47 watts of electricity per square meter.  That may not sound like much, but a bit of high school math reveals that if this design scales up (even assuming just 30 watts/meter), a 1km by 1km plot of land (a bit over a half mile on each side) would produce as much electricity as one of today’s wind farms with two hundred 1.5MW 300-foot towers spread over many square miles. Put another way, a patch of land 200 feet on each side would produce the same amount of electricity as a single 1.5MW turbine, which generally needs a safety buffer of at least 500 feet on all sides.  The downsides of the new approach are that the productive wind installation would use all of the land in its footprint, unlike current wind farms in which the distantly-spaced turbines leave plenty of room for grazing or planting.  Horizontal axis turbines can also suffer more stress under high winds, though undoubtedly new materials and engineering approaches will address this issue.

There’s clearly a long way to go to bring this new design to utility-scale wind production, but of all the new approaches to wind energy, this is one of the most promising!

For more on Dabiri’s work, see this Caltech press release and visit Dabiri’s lab’s web page, which includes a video and links to a Powerpoint and the recently published paper.

The Syracuse Post-Standard reports that a study of real estate sales in three upstate New York counties has found that being closer to wind turbines can lead to reduced sales prices.  In two of the three counties, property values appear to have dropped by 8-15% for homes situated a half mile from the nearest turbine (which usually means several more are within a mile or two); the price drop was only slightly less for homes within a mile, while there was a smaller, 2-8% drop for homes within 3 miles of a turbine.  However, the third county studied showed no price reduction after the wind farm was constructed; the authors found that in this county, prices actually rose a bit just after construction, then settled  back to no significant change. This study uses a hedonic analysis methodology similar to two previous studies (Hoen and Hinman) that found no significant price change.  This new study, by Martin Heintzelman and Carrie Tuttle of Clarkson University, differs from the previous studies in that it does not combine all results, but rather looks at each county individually.

The Heintzelman study is still being finalized; an earlier version that combined all locations into an overall negative impact has circulated since March, but a new version that separates the locations and finds the more nuanced results is now available.

Riga, Michigan has adopted a wind farm ordinance that limits noise at nearby residences to 45dB during the day and 40dB at night, and the wind developer says they cannot meet these limits on the land they’ve leased.  The rules also establish a distance limit of 4x the height of the turbines; this amounts to a bit over a third of a mile. There’s a good chance that wind boosters will spur a township referendum to repeal the new rules.  Three other local townships where wind development is planned are working on ordinances, and there is some indication that they will come to a similar conclusion about acceptable noise levels.  It is not clear from initial press reports whether the Riga ordinance includes the option of obtaining permission from willing landowners to build closer or allow slightly more noise at their homes.

Joshua Nolan, director of the nonprofit Interstate Informed Citizens Coalition, said “The ordinance as it exists is probably the best compromise.” With many acousticians suggesting a 35dB night time noise limit (see recent AEI Wind Farm Noise 2011 report), and the industry more accustomed to building wind farms to meet a 45-50db threshold, the Riga ordinance is a moderate attempt to provide more noise protection for neighbors.  Yet it may also be a good illustration of the fact that such protection can indeed preclude development in some rural areas with more population density than the wide-open west.  Many towns and counties are attempting to find the middle ground where development can take place, but citizens are not unduly impacted by noise; in some areas, there may not be enough room to keep turbines far enough from homes to meet this goal.  In this situations, the localities will need to decide whether wind development or local peace and quiet is more important to them.  In some areas, it may be possible to find enough willing neighbors to accept louder noise at their homes to allow smaller wind projects to proceed, while keeping turbines noise to 40dB, or even 35db, at homes of those who wish to maintain the current rural soundscape.

An unprecedented court case has begun in the UK, which could determine whether noise impacts become more widely considered to be of importance around wind farms.  Jane and Julian Davis moved out of their home in 2006 after the wind farm began operation, saying the sound was ‘unbearable’ even though they wore earplugs at night and installed double glazing at the farmhouse in Deeping St Nicholas, Lincolnshire. in 2008 they were unable to get a real estate agent to list the home for sale, saying they could not determine a fair market value due to the noise from the turbines just under a kiilometer (about a half mile) away.

Their case is being heard by London’s High Court, and is believed to be the first UK case to seek damages for a “noise nuisance” caused by a wind farm.  According to a detailed post at Business Green,

Mrs Davis, whose husband’s family cultivated Grays Farm for more than 20 years before they moved out, said it had been a “nightmare” living there, and the family had no option but to leave. She told the Strand News Service on Monday that the humming sound created by the turbines was very unpredictable and mainly occurred at night. “You can never get to bed with the assurance that you will stay asleep,” she said. Their lawyers are seeking either a permanent injunction to shut down the turbines or damages of up to £2.5m to compensate the couple for the disruptive effect on their lives.

The case, which is expected to last three weeks, started on Monday but was adjourned until today so the judge and lawyers in the case could carry out a site visit. “Their lives have been wholly disrupted by that noise,” he told the court, also alleging the main operator had tried to “impose a code of silence on those examining or recording the noise that the turbines in this location have caused”.

But William Norris, QC for the owners, operators and landlords of the wind farm, rejected claims that the machines created an unacceptable noise nuisance, suggesting the couple may have become “unduly sensitised to sounds that would not adversely affect the ordinary person”. He accepted that their “amenity” had been affected, but said the couple had “a gross over-reaction to what they undoubtedly do hear”.

The Spaulding Guardian elaborated on the two sides’ perspectives:

The Davis’s barrister said in court that the developers tried to “attack the credibility and reasonableness of the claimants rather than examine what they were actually being told. From the defendants’ witness statements, and the material they wish to put before the court, it seems that those attempts to undermine the claimants, to say they are over-sensitive, that they are exaggerating and over-reacting, will continue during the trial,” the barrister added.

He claimed the defendants had been irked by Mrs Davis’ eagerness to “speak publicly” and that she was being attacked for refusing to “put up with the noise”.

The QC for the developers and turbine host families accepted the couple heard sounds they genuinely believed to be “objectionable” after the turbines were installed but argued they could not be considered “dispassionate and reliable witnesses” and said Mrs Davis is prone to exaggeration and “favours hyperbole rather than balanced description”.

The case adjourned on July 6 for the judge and and lawyers to do a site visit.

The Minnesota PUC has approved a controversial wind farm in Goodhue County, where a county ordinance setting a nearly half-mile setback was facing off against a 1500-foot setback that was originally planned for the project.  The PUC slightly increased the setback limit from 1500 feet to 6 rotor diameters, or 1630 feet.  But while giving approval for the closer siting, the PUC also is requiring developers to engage in “good faith” efforts to negotiate agreements with neighbors closer than the county limit, which is 10 rotor diameters, or just under a half mile.  It’s unclear how such negotiations might proceed, or whether the PUC or courts would respond if negotiations fail.   Over 200 landowners have signed lease agreements to host turbines, while a contingent of locals has pushed for greater protections for neighbors.

UPDATE, 9/14/11: Goodhue County will file request for PUC to reconsider their permit.
UPDATE, 12/4/11: Goodhue County decides not to appeal the PUC decision.
UPDATE 2, 9/15/11: Sixteen motions were filed with the PUC to reconsider the permit, with some of the filers using fightin’ words; a court challenge is also mentioned as a possibility.

The PUC’s decision is a stumbling lurch toward the sort of approach that makes sense to AEI, which would establish larger setbacks such as the county standard, while encouraging negotiated agreements with neighbors who live closer.

For more on the Minnesota decision, see these three articles from RenewableEnergie.com and this one from North American Windpower. This Reuters piece last week set the stage nicely as well.

UPDATE, August 1: 200 residents who live within a half mile of the proposed project and are not already in line to receive lease payments as hosts of turbines have been offered $10,750 each by the developers of the 50-turbine wind farm.  This is in response to the PUC order that they make a good faith effort to obtain agreements from these neighbors.  The offers total about $2 million, a small increase in the previous $180 million project budget.  It’s interesting to me that there are that many landowners within a half mile; another 200 have are already part of the project as lessees. Past experience suggests that in areas like this, with so many people being affected, there is apt to be a higher likelihood of negative reactions, as compared to wind farms in locations where residences are sparse, and mostly working farms or ranches.

An Australian wind farm was derailed this week when the Environment Resources and Development Court in the state of South Australia ruled in favor of a dairy farmer who challenged an earlier approval.  The Court rejected evidence related to possible health effects, but ruled that the planned wind farm would impact on the “visual amenity” of the area to an unacceptable degree.  The proposed turbine layout included several turbines within one kilometer (just over a half mile) of Richard Partridge’s dairy farm; 14 other homes were also within 1km of the nearest turbine, with several, including Partridge, facing the prospect of having turbines within 2km (a mile and a quarter) in several directions.  In his submissions of concern, Partridge stressed that audible noise would impact his quality of life and possibly the well-being of thousands of nearby dairy cows; his statement to a Senate Committee concluded:

Our landscape is a non-renewable resource. We cannot create more of it. It is the background and setting to our lives, and helps to identify us as Australians. The Australian landscape is a resource which we hold in trust for future generations. As its present custodians we have a responsibility to conserve and manage it wisely, protecting it from inappropriate development, so that it will enrich the lives of our children and successive generations.

While the Court heard evidence from a Waubra woman whose home 700m (2100 feet) from turbines was purchased by the developer after she complained of health impacts, the justices ruled that health effects are too uncertain to be blamed on the turbines, but that the rural nature of the area deserved more protection than the Allendale East Wind Farm layout could provide.  The deciding factor appeared to be the dramatic new vertical elements being introduced into the landscape by the turbines (see judgement). In Australia and New Zealand, “rural amenity” is more widely considered a valid basis for assessing the impacts of development, while in the US and Canada, assessment tends to stress objective measurements of noise, with quality of life concerns minimized as simply NIMBYism.

As for noise levels, the Court noted that it accepted at face value testimony from wind farm neighbors elsewhere who reported clearly hearing turbines at distances from 700m to 3.2km, but could not extrapolate from these reports elsewhere to apply such concerns to this site.  Justices agreed with testimony from the developer’s acoustical experts, which project noise levels to remain below the statutory limit of 40dB or 5dB over ambient, whichever is greater.