Wind turbines are a relatively new source of noise, which began to be analyzed in detail by acousticians only in the 21st century. In research on the annoyance of noise, there is a common belief that the louder the noise, the more annoying it is. “This statement is true for noise sources such as airplanes, railways and cars” – he explains prof. Preis. He points out that the noise generated by wind turbines is quieter than these sound sources, and yet, at the same sound level, the noise of a wind turbine is assessed as more annoying.
There's no point in talking about distance?
For several years, subsequent countries have begun to gradually introduce noise standards relating to this new sound source. In Poland, turbines are still treated as “other objects and activities that are a source of noise”, and the possibility of their location in relation to houses – as noted by the project implementers HETMAN – the “10H” rule came into play. This provision introduced the requirement to maintain an appropriate distance for newly built wind farms from buildings, indicating that this distance should be at least 10 times the total height of the windmill including the blades.
“In no other country are regulations regarding wind turbines presented 'in meters', as is the case in Poland, and in the values of sound levels permissible for this type of noise,” says Prof. in an interview with Nauka w Polsce. Anna Preis. He adds that the exception is probably Bavaria in Germany, where meters are mentioned.
“The issue of meters should disappear in the regulation on permissible sound levels for wind turbines,” the scientist believes. In her opinion, this is important because the same turbine, at the same distance from the house, can generate noise that will vary by up to 10 dB depending on the wind speed.
Prof. Preis argues that the criterion of nuisance expressed in meters makes no sense. “With respect to other noise sources, no one would think of establishing a criterion for car noise annoyance in meters, i.e. the distance of the highway from houses. This is done in relation to the sound level for all other noise sources. So why should turbines be an exception? ” – wonders the scientist.
“Hetman” examines the noise nuisance of wind turbines
Over the course of three years, a team of scientists as part of the “Hetman” project examined, among others: noise nuisance from wind turbines, possible methods of noise monitoring and forecasting, the impact of infrasound on human health and methods of reducing turbine noise.
As noted by prof. Preis, the noise of wind turbines does not pose a threat to human health. “At most, it may be irritating to some people. However, if appropriate conditions are met, i.e. the permissible sound level limits are not exceeded, even the impression of annoyance should not appear,” he adds.
As part of the project, scientists investigated what physical parameters of wind turbine noise determine the perception of annoyance and how it can be minimized.
“The most important result of the project is the proposal of the permissible sound level for wind turbine noise, confirmed by measurements and surveys in the field and experiments conducted in the laboratory,” says Preis. – These values only apply to wind turbine noise, they are different for other noise sources.
Measurement rules need to be unified
Currently, wind turbine noise is classified as “other facilities and activities that are a source of noise”. The scientists propose that there should be separate requirements for wind turbines and that the assessment time be changed from 8 hours of day/1 hour of night to 16 hours of day/8 hours of night, respectively. The proposed changes also concern the simplification of the classification of types of areas subject to acoustic protection (same permissible value for all types of residential areas). Depending on the type of terrain, the proposed values are: 45-50 dB for the day (currently 45-55 dB), and 40-45 dB for the night (unchanged).
Moreover, the project implementers propose to define and standardize the principles of wind turbine noise management. “These rules will appear in the Good Practice Guide we are preparing, which must be met at every stage of operation of a wind turbine farm, from planning to control of the operation of a given farm,” says Dr. Preis.
This document will describe in detail, among other things, the method of measuring wind turbine noise, what measurements should be performed when controlling the operation of such a farm, what should be done when permissible noise levels are exceeded, etc. It will also include instructions for farm managers on how to reduce noise. wind turbines when, for example, there are complaints from residents.
“We hope that the data and conclusions we presented will become the basis for a reliable regulation of the issue of wind turbine noise in Polish legislation,” the acousticians note.
Renewable energy discovers new issues
In their opinion, Poland is facing many challenges related to… increasingly dynamic progress in renewable energy. “The sooner we regulate issues related to its development, the sooner we will be able to focus on the real benefits of using renewable energy,” emphasized the project implementers.
As part of the “HETMAN” project, a monitoring station for noise generated by wind turbines was also constructed.
What is the “Hetman” project?
The POL/NOR 2019 project “Healthy society – towards optimal management of wind turbines' noise” (acronym: HETMAN) was created as a scientific response to ongoing discussions in both the media and political circles about noise and the potential harmfulness of wind turbines. . The project was implemented by a consortium of entities. Its leader is the Adam Mickiewicz University in Poznań, and it is accompanied by a research institute SINTEFTrondheim, Norwegian partner, AGH University of Science and Technology in Kraków, Central Mining Institute in Katowice, InInstitute of Occupational Medicine in Łódź and Institute of Environmental Protection in Warsaw. Business partners included Akustix, a company dealing in comprehensive noise monitoring, as well as: Polish Wind Energy Association.
The project consisted of a total of seven tasks. The “HETMAN” project was financed by Norwegian funds and the state budget and its operator was the National Center for Research and Development. (PAP)
Anna Mikołajczyk-Kłębek (Science in Poland)
