According to the French National Academy of Medicine, there is a real risk that low-frequency noise from wind turbines can cause health problems among people living nearby. In the absence of any scientific proof, it recommends a ban on installing wind turbines with rated capacities of more 2.5 MW in size within 1500 metres of houses in France while in-depth studies are carried out. The academy further recommends that turbines be classified as industrial installations and thereby become subject to specific noise regulations. On the positive side, it finds there is no evidence of harm from infrasound, nor from the stroboscopic effect produced by turbine blades when the sun is low in the sky, which some claim provokes epileptic seizures.
The academy makes its recommendations in a report, published in March, that was prompted by a request made a year earlier by an anti-wind group based in Brittany, formed to "protect" an area known as Abers. The group asked government health minister Xavier Bertrand to examine the possible adverse effects of wind turbines on public health. An academy working group has since been examining the evidence.
Much of its information is from papers presented at an international conference on wind turbine noise held in Berlin in October 2005. The working group also refers to noise evaluation surveys carried out at wind plant in France as well as studies by the British Wind Energy Association, among other documents. In addition, the group interviewed a number of people, though none of the official bodies representing the wind industry, nor France's energy agency, ADEME.
The national Renewable Energy Syndicate (SER) and the French Wind Energy Association (FEE) are surprised at being ignored by the academy. The feel they could have contributed a "certain amount of factual information" to the investigation.
General ill health
The academy report notes that some people living close to turbines complain of health problems and cite noise as the number one cause. "Noise can have a real impact, not yet well understood, on health," the authors say, noting that at even moderate intensities, irregular and insistent noise can lead to stress, disturbed sleep and general ill-health. Problems mentioned range from tiredness and headaches to vomiting, insomnia and palpitations.
While recognising the effects of noise are often subjective and difficult to quantify, the report recommends two studies be carried out to prove whether noise from wind turbines really is harmful. The first would record noise levels over several weeks inside houses near turbines. The second would investigate health problems among the general population that potentially could stem from wind turbine noise and correlate them to the distance from the machines.
The results would be used to establish a minimum distance from the nearest dwelling at which turbines could safely be built -- even if this has to be unique for each site to take account of the local climate and topography. In the meantime, the report recommends no turbines be built within 1500 metres of a house.
The report criticises current regulations governing wind plant for not stipulating a minimum distance and for not specifically tackling noise emissions from turbines. Instead, turbines fall under general regulations on noise. These state that the maximum permitted increase in noise levels is three decibels at night and five decibels during the day, measured outside the house. The report argues that the regulations are not only out of date, but also inadequate because they do not take account of the "industrial nature of turbines, the great variability in noise emissions and technical advances in the simulation and measurement of noise levels."
As SER and FEE point out in a joint response to the academy, the government is in the process of drawing up standards specifically for measuring turbine noise emissions; these will probably be issued towards the end of the year. SER/FEE also stress that France has some of the strictest legislation in Europe concerning noise. As part of the permitting process, wind power projects are subject to an impact study, which includes acoustic tests, and a public enquiry at which local residents can voice their concerns. Further acoustic tests are carried out during construction and validated by the local public health authorities. If, once the plant is operational, people complain about noise, further tests are carried out. If noise levels are found to exceed the limits, the operator has to make changes -- for example, stopping turbines during periods of light wind, when noise is more obvious -- to comply with the law.
Lack of logic
SER and FEE question the logic of banning turbines of 2.5 MW and above when these new, larger turbines are much quieter than less powerful models of earlier generations. "There is absolutely no correlation between turbine size and potential noise emissions," states SER's André Antolini. Noise is relative: SER/FEE quote their own study showing noise emissions of 100 decibels at the height of the rotor, 55 decibels at the foot of the tower and 35 decibels 500 metres from the turbine, which is the same level as a normal conversation. As regards health problems, ADEME points to countries such as Denmark and Germany, which have a long history of wind plant without any apparent ill effects on the population at large.
The wind industry welcomes the prospect of serious scientific studies which would help dispel some of the myths surrounding wind power, but argues there is no justification in imposing a ban in the meantime. The studies, it says, must be carried out by independent acoustic experts under government auspices if they are to be acceptable to all sides. The results would then provide an objective basis for debate in what is, after all, a very subjective area. "People who find turbines ugly also think they are noisy, without taking account of the actual noise levels," notes ADEME, quoting from a Danish study.
The report has "complicated matters" says Marion Lettry of SER. It is being used by anti-wind groups to oppose applications. As a result, the permitting process is taking longer than ever. So far, industry minister François Loos has not taken any action, but SER is sending a circular to prefects, the local government officials in charge of the process, explaining that the report provides no evidence to justify projects being turned down.