Sounding off on Wind turbines
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) www.wind.appstate.edu/reports/06-06Leventhall-Infras-WT-CanAcoustics2.pdf
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