Sounds from Wind Turbines: Theory, Practice, Assumptions, and Reality
Professor Philip J Dickinson
As the world supply of fossil fuels diminishes, many countries are looking towards more sustainable sources of power to feed the needs of a fast growing population. Wind power is high on the list of possible energy sources, and wind power industry is being developed throughout the world at an astounding rate with little thought about the effects on local communities of the sound and vibration the turbines generate. To the general public at large, a wind turbine will sit quietly turning when the wind blows, generating electricity and causing a problem to no-one, except those people that do not want to see the landscape changed to include the sight of these graceful machines, many of which are more than 100 metres tall. It is known, however, that any machine generates noise, and a wind turbine is no exception. The noise emission may not be of the intensity of that generated by transportation, but it has unique spectral and temporal characteristics that make it stand out from all other background sounds other than in the presence of running water or surf.
Numerous national standards have been developed by countries in the developed world to predict and manage the noise from such wind power establishments (or wind farms as they often are called). The standards, however, are highly questionable although developed by working groups with a good basic knowledge of acoustics. The problem is that standards cost money, and inevitably are funded by those organisations that are concerned only with what the standard can do to advance their business interests. The standards working group will ostensibly have members to cover the entire range of interests from developers, energy authorities, government officials, and the general public. In reality most of those involved will have an interest in the development of the wind farms and those at the receiving end of the noise, or concerned about the health implications on local communities will have little or no influence. The standards leave much to be desired and this paper will endeavour to cover some of the points of contention.
The Assumptions
Most wind turbine noise standards, including the New Zealand Standard NZS 6808, are based on the following premises:...
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