By Dave Elliott
It has been an eventful year for renewables. While progress continues apace, with renewables now supplying around 15% of electricity in the UK and 22% of global electricity, in this pre- Xmas post, rather than spelling out all the good news, I will look at some of the less good stories from the year- concerning wind power and CSP. (more…)
By Dave Elliott
This year has seen yet more negativity on wind power, and proposals to cut support for on -land wind, despite this being the cheapest of the major new renewables. While overall public support for the use of wind energy remains high, in practice many new on-land projects are now opposed: two thirds of applications have been turned down in the last year. Much of this has been about visual intrusion, ‘Not In My Back Yard’ concerns relating to treasured views and, more prosaically, possible impacts on house prices. (more…)
Most people are surprised how quiet modern wind turbines are when they visit a wind farm. Mechanical noise is usually minimal – even right up close. And the aerodynamic blade noise is often less than the noise of wind in any trees or bushes near by. However in some locations some problems have still been reported.
An international panel of experts convened by the American and Canadian Wind Energy Associations, recently released a report based on a review of a large body of scientific literature on sound and health effects with regard to sound produced by wind turbines. After extensive review, analysis and discussion, the panel concluded that sounds or vibrations emitted from wind turbines have no adverse effect on human health – an issue that was recently given new prominence by a US report, which claimed that physiological damage could be caused by low-frequency sound from wind turbines (see my earlier blog).
The new review states:
- There is no evidence that the audible or sub-audible sounds emitted by wind turbines have any direct adverse physiological effects.
- The ground-borne vibrations from wind turbines are too weak to be detected by, or to affect, humans.
- The sounds emitted by wind turbines are not unique. There is no reason to believe, based on the levels and frequencies of the sounds and the panel’s experience with sound exposures in occupational settings, that the sounds from wind turbines could plausibly have direct adverse health consequences.
Even so, there are still reports that aerodynamic “swishing” sounds from wind farms are an issue at some sites at night – disturbing some people’s sleep.
The Telegraph quoted a nurse, Jane Davis, who says that she was forced to move from her home in Lincolnshire after eight wind turbines were built in 2006. “All I know is the amount of health problems people have suffered,” which she said included sleep deprivation, tinnitus, depression and psychological stress “seem to be excessive”. She added: “These things have devastated my life.”
The AWEA/CWEA report does say that, although “work with low frequencies has shown that an audible low frequency sound does not normally become objectionable until it is 10 to 15 dB above hearing threshold”, an exception is “when a listener has developed hostility to the noise source, so that annoyance commences at a lower level”. They note that “a major cause of concern about wind turbine sound is its fluctuating nature; some may find this sound annoying, a reaction that depends primarily on personal characteristics as opposed to the intensity of the sound level” and report that a “study of more than 2000 people suggested that personality traits play a role in the perception of annoyance to environmental issues, such as sound”.
However, they add, a bit abruptly perhaps, that though “some people may be annoyed at the presence of sound from wind turbines; annoyance is not a pathological entity”. It’s certainly true that once a noise gets annoying, however low the level (e.g. a tap dripping), it can become intolerable.
The report concludes that, though “there is no evidence that sound at the levels from wind turbines as heard in residences will cause direct physiological effects…a small number of sensitive people, however, may be stressed by the sound and suffer sleep disturbances”.
That rendition may not please sufferers! Of course, you could say that road traffic and aircraft landing and taking off can lead to much more noise annoyance for a lot more people, as can city living. But should we be adding more stress? Rural areas are, after all, usually quieter, which is one of their attractions. Or, assuming it cannot be resolved by careful wind-turbine location or modified operational patterns, is that just a cost that has to be borne by a small minority, who might in any case find a conventional power plant near them significantly less attractive?
The government’s view certainly seems unchanged. NewEnergyFocus reported that in January, energy minister David Kidney dismissed claims that the permitted night-time noise limit for onshore wind turbines is too high. He said that the 43 dB night-time limit in the ETSU-R-97 guidance was derived from the sleep disturbance criteria in Planning Policy Guidance 24, with an addition to allow for an open window. He said that ETSU-R-97 gave indicative noise levels thought to offer “a reasonable degree of protection to wind farm neighbours” and that there was no evidence that they needed to be reviewed. He added that residents’ comfort had to be balanced with the needs of wind-farm developers and so the guidelines should not place unreasonable restrictions on wind-farm development or add unduly costs and administrative burdens on wind-farm developers or local authorities. He concluded: “We have no robust new evidence to suggest that the current guidance is not achieving its aim.”
In a book to be published in Oct, Dr Nina Pierpont, a New York paediatrician, says she has identified a ‘wind turbine syndrome’ (‘WTS’) due to the disruption or abnormal stimulation of the inner ear’s vestibular system by wind turbine infrasound and low-frequency noise, the most distinctive feature of which is a group of symptoms which she calls ‘visceral vibratory vestibular disturbance’, or VVVD. Evidently this can cause problems ranging from internal pulsation, quivering, nervousness, fear, a compulsion to flee, chest tightness and tachycardia – increased heart rate. Turbine noise can also trigger nightmares and other disorders in children as well as harm cognitive development in the young. However, Dr Pierpont made clear that not all people living close to turbines are susceptible.
That might explain why, as the British Wind Power Association (BWEA) noted in an initial response, ‘an independent study on wind farms and noise in 2007 found only four complaints from about 2000 turbines in the country, three of which were resolved by the time the report was published’.
Nevertheless, it’s wise to be cautious. Some small domestic scale machines, which being small have very high rotation speeds, can be noisy, but audible noise from large modern wind turbines is nowadays hardly an issue, with gearless, variable speed turbines being very quite, since the blade rotation speed is better matched to the changing wind speed, thus increasing energy transfer efficiency and reducing aerodynamic noise. But low frequency sound might conceivably be a problem for some people. The only way to find out if this is this case and then to assess it’s significance, is to carry out research on a large scale – Pierpont’s sample was tiny, evidently based mostly on interviews with just 10 families living near wind turbines – 38 people!
In 2006 DTI published a study by Hayes McKenzie, which investigated claims that infrasound or low frequency noise emitted by wind turbine generators was causing health effects. The report concluded that there was no evidence of health effects arising from infrasound or low frequency noise generated by wind turbines. But the report noted that a phenomenon known as Aerodynamic Modulation (AM) was in some isolated circumstances occurring in ways not anticipated by ETSU-R-972, the report which described the method of assessing the impact of the wind farm locally. So the Government commissioned Salford University to conduct a further work. This study concluded that AM is not an issue for the UK’s wind farm fleet. Based on an assessment of 133 operational wind projects across Britain, the study found that, although the occurrence of AM cannot be fully predicted, the incidence of it from operational turbines is low. Out of all the working wind farms at the time of the study, there were four cases where AM appeared to be a factor. Based on these findings, the Government said it did not consider there to be a compelling case for more work into AM, but it would keep the issue under review.
Pierpont’s views have attracted significant media attention, with for example, the normally pro-wind Independent even suggesting that ‘there is a prudential argument for postponing the commissioning of land-based wind farms until they are shown to be safe’. A bit less radically, Pierpont has called for a 2 km safety zone.
The NHS website stepped in with a short critique, which noted that “The study design was weak, the study was small and there was no comparison group. There is also no information on how the group was selected in the first place and some uncertainty as to which countries these people come from.” It concluded ‘it is physically and biologically plausible that low frequency noise generated by wind turbines can affect people’ but, ‘this study provides no conclusive evidence that wind turbines have an effect on health or are causing the set of symptoms described’.
The BWEA, in a special Factsheet, then went on the offensive, noting that ‘Dr Pierpont is a known anti-wind campaigner’. And it pointed to a peer reviewed study by Geoff Leventhall which had refuted the allegations about infrasound, concluding that they were ” irrelevant and possibly harmful, should they lead to unnecessary fears”.
The Pierpont study does sound very weak but, to clear the air, it seems that the issue has to be resolved once and for all by an authoritative independent study.
Geoff Leventhall ‘Infrasound from Wind Turbines – Fact, Fiction or Deception?” Canadian Acoustics Vol. 34 No.2 (2006)