The answer is blowing in the wind
By Peter Sims
13 Sep 2011
Wind power is a youthful and growing industry, but growing in parallel is the level of protest from neighbours affected by noise issues - from surprisingly specific situations.
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Noise Monitoring | Noticias
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| Ampliar imagen | | Achany windfarm in the highlands of Scotland, courtesy of Graeme Smith |
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Although wind power is nothing new, its adoption on an industrial scale is a fairly recent phenomenon, and as with most large technological developments it’s one that we humans have become quickly used to. However, wind energy continues to be a polarising issue as energy developers expand the alternative generation sector, and concerned citizen groups push back, citing excessive noise from turbines as one of their primary concerns.
A recurring theme
The news media frequently document the latest objections of concerned local residents to prospective or existing turbine installations. In what was posited as a landmark ruling in June this year, a site in the highlands of Scotland was actually forced to close by the local government, as a result of two local complainants. While this shutdown was in fact temporary, and lasted for four days before it was lifted, it was nevertheless in response to the complaints of just two local residents, citing disturbances that occur only under specific circumstances. Significantly, this is not an isolated example, but part of a common theme that is recurring around the world.
| “If we carefully monitor the vibration and noise wind turbines generate we are well-positioned to minimise their impact on people" |
In Ontario, Canada, a ‘Windyleaks’ campaign looks set to create a storm, after an internal memo showed a senior environmental agency official opining that even Canada’s world-leading noise limits on wind turbines are still too high for the real world. Here, the news has been brandished as a political weapon with which to beat the government in upcoming elections, which is a testament to the emotive power of the issue. Meanwhile in Australia, the US and more countries besides, doctors regularly speak out about ‘Wind Turbine Syndrome’ – after treating patients who have been adversely affected by the noise from nearby turbines.
Development in a young industry
Of course, it’s all a relatively new area that is under constant development. Studies, science and manufacturers are developing all the time in this relatively young industry. As a case in point, as recently as July last year, news was released of a revolutionary new design of turbine that looks set to revolutionise energy generation capacity. Here, Japanese researchers have demonstrated apparently radical blade speed increases through the simple addition of a ‘ring’ around the circumference of the blades. While this is an unproven concept as yet, and remains in the early stages, it nevertheless reflects the youth of the whole industry.
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It is with this youth in mind that this year saw the establishment of a dedicated research centre in Canada. Here, the continent of North America’s first Wind and Renewable Energies Centre of Expertise (WRECE) has been established in the Centre for Engineering Innovation, with $1.4 million in research equipment supplied by Brüel & Kjær to University of Windsor’s Noise Vibration and Harshness-Sound Quality Group (NVH-SQ). The leader of WRECE, Professor Colin Novak, taught the first graduate-level course this summer.
Research and technology holds the answers
As Professor Novak says, wind turbines are now an integral part of the landscape and an important source of future power generation, so ongoing research into noise, vibration and efficiency is essential.
“If we carefully monitor the vibration and noise wind turbines generate we are well-positioned to minimise their impact on people. Wind energy is a constantly evolving technology that will have an impact on the lives of everyone – not just in our immediate community, but around the world.”
Professor Novak adds that advanced study of the turbines’ gearboxes and blades will also be part of the research. “These are huge structures with gearboxes the size of an automobile,” he says. “We want to find ways to monitor the conditions inside these gearboxes with the goal of making them more efficient. It is also important to find efficiencies in the shape and function of turbine towers and blades.”
The devil is in the details
What’s amazing within the industry at present, is how there is very little detailed monitoring of noise levels, while community engagement seems to be lacking. Uniting many of the public grievances, and all of those cited above, is that the problems emerge from highly specific situations. These require a somewhat nuanced understanding of the noise levels under different circumstances, such as at night or in different weather conditions, rather than the one-size-fits-all approach of slapping on an absolute and universal decibel limit.
| “I cannot understand why large-scale wind turbine developments do not perform continuous noise monitoring. Sharing unbiased noise data collected from wind farms might be a way to bridge the divide between the two groups on the opposing sides of this issue” |
In the aforementioned case in Ontario, the argument centres around the minimum setback distance of turbines from adjacent housing, which according to the senior ministry official Cameron Hall, was based on the assumption that the “sound contamination” they emit does not have a “tonal quality or a cyclic variation quality.” In Scotland meanwhile, the locals’ complaints focused only on specific time periods, while in Australia, the grievances cite insufficient consideration of the proximity of turbines and housing.
The picture that emerges shows that zones where humans and wind turbines meet require more detailed understanding and monitoring, along with an appreciation of the many variables that exist locally, if public consternation is to be successfully avoided. It is no small matter that in May, the London branch of the Institute of Acoustics gave a presentation entitled “Statutory nuisance: Wind farms and wind turbines,” in which they “strongly recommended that investigation of noise complaints involving large-scale wind turbines should include detailed assessment of the weather conditions.”
Openness and public consultation
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| Ampliar imagen | | Brüel & Kjaer's Noise Sentinel solutions mitigate public concerns at major airports around the world |
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But equal to the importance of this is the necessity of effective public consultation, and of open information sharing – which help to mitigate public reactions, or even forestall them completely. As the Institute of Acoustics’ presentation went on to say, “Providing noise-level based information to a wind farm operator may help facilitate a rapid remedial and collaborative response to an initial or informal approach by a local authority, which can sometimes resolve noise problems more quickly than the formal statutory noise procedure.”
The technology to collect this data is presently available and has already been used for a long time to monitor aircraft noise at airports. One example of such technology is the Brüel & Kjær Noise Sentinel, with which noise monitors can be located at the property line of the wind turbine development, or even at nearby residences. Those monitors can continuously log the noise levels as well as all of the weather parameters, so the data can be correlated. Along with this, threshold alarm levels can be programmed so that if a noise guideline is exceeded, a notice can be sent to the operator for a responsive action. Arguably the system’s most significant benefit is that the data can be made available on the web for everyone to see, and understand.
It seems then, that perhaps the wind industry is simply seeing a lag in the response to this kind of technological demand, just as the aerospace industry before it took some time to adopt the comprehensive noise controls that we see today. What is certain however, is that the negative effects of complaints from affected residents will not stop, making effective mitigation of their complaints vital.
With thanks to Professor Colin Novak.
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