Abstracts: ISEE 20th Annual Conference, Pasadena, California, October 12–16, 2008: Contributed Abstracts
Wind Turbines and Noise: Is There a Minimal Siting Distance?
The share of renewable energy sources is in constant increase in France and worldwide. This orientation notably results from the need to diversify energy sources and reduce dependency on fossil energies. It also takes places in a global context of greenhouse gas emissions reduction. In France the wind turbine production was of about 0.75 GW in 2005 and is now more than 2.7 GW. In spite of the growing interest for renewable energy sources, their potential environmental and health impact is a source of concern. This is the case for wind turbines for which residents put forward the noise generated by the future wind parks to contest their construction. These concerns led the French National Academy of Medicine to temporarily recommend a minimal distance of 1500 metres between wind turbines (>2.5 MW) and habitations. Following this, the French ministries in charge of health and environment commissioned AFSSET to further investigate the acoustic impacts of wind turbines and produce detailed recommendations.
To perform the study, a work group constituted of experts in acoustic, metrology and health effects was set up. AFSSET's expertise was conducted in close cooperation with the Agency for environment and energy management (ADEME). The experts reviewed the available data regarding wind power developments and perspectives, health effects of noise, regulations applicable to wind turbines and wind parks in various countries as well as noise levels measured in residential areas. Regional authorities were also interviewed through a questionnaire (97 regional authorities investigated, return rate 42%) to understand the current management practices and siting distances. Numerical simulations were performed to assess noise levels induced by wind parks in various topographic and meteorological conditions. There are basically two regulation strategies in noise management: acceptance levels based on absolute noise (including ambient background and other sources) and acceptance levels based on emergence (the contribution of a specific source to the ambient level). Absolute levels are used in some countries (e.g. Germany, Denmark, Greece and Sweden), while a combination of absolute and relative levels are used in other countries (e.g. England, Australia, New Zealand and France). The French regulation, which is amongst the most restrictive, relies on an emergence limit of 3 dB(A) at night.
Results and Discussion:
The numerical simulations carried out indicated that the noise emergence induced at 1500 m remains weak and generally below 3 dB(A). Nevertheless, higher noise emergences may occasionally be found for particularly penalizing conditions. Questionnaire results indicated that the mean current siting distance is of 650 m (n = 180). Complaints from residents were reported for about 10% of wind parks. Considering this, and the lack of direct health effects, the setting of a precautionary distance of 1500 m does not seem relevant. Besides, the advantage provided by such a straightforward approach must be put in balance with its consequences on wind park development. Finally, the workgroup concludes that the existing simulation capabilities are sufficient to support the implementation emergence regulation and should be further developed within the existing impact studies framework.© 2008 Lippincott Williams & Wilkins, Inc.