WINDFARMperception Visual and acoustic impact of wind turbine farms on residents

Transcription

1 Project no WINDFARMperception Visual and acoustic impact of wind turbine farms on residents FP Science-and-Society-20 Specific Support Action Publishable Final Activity Report Period covered: January 2007 August 2008 Start date of project: January 1, 2007 Duration: 20 months Report date: November 25, 2008 Project coordinator: Frits van den Berg Project coordinator organisation: University of Groningen

2 WINFDFARMperception Final Activity Report p. 1 WINDFARMperception: Visual and acoustic impact of wind turbine farms on residents Publishable Final Activity Report 1. Project objectives The project aimed to investigate the relation between a) the generation of wind energy by onshore wind farms and b1) the exposure of the residents to noise originating from these neighbouring wind farms, as well as b2) the impact these wind farms have on the residents perception concerning their health and well being. Therefore the objective of the WINDFARMperception project was: o to provide knowledge on the perception of wind turbines by people living in proximity to wind farms; o to evaluate human responses to audio and visual exposures from wind turbines and to give insight in possibilities to mitigate the local impact of wind farms. Or, in short: how do residents perceive a nearby wind farm and how does it affect them? 2. Project partners Partners in the project were: o University of Groningen (RUG), the Netherlands: Frits van den Berg of the Science Shop for Physics who contributed expertise in acoustics and atmospheric physics; o Göteborg University (UGOT), Sweden: Eja Pedersen with expertise in the perception of wind turbines by the local population and surveys to measure the impact; o University Medical Center Groningen (UMCG), the Netherlands: Jelte Bouma of the Science Shop for Medicine with expertise in setting up surveys and analyzing survey results. Frits van den Berg published a thesis on wind turbine noise in May 2006, Eja Pedersen on wind farm perception in September Both have written several papers about the sound

3 Final Activity Report WINFDFARMperception p. 2 produced by wind turbines and the perception of wind turbines. These have been published in peer reviewed scientific papers or presented at international conferences. Jelte Bouma was involved in the impact of chronic diseases on daily life activities and the quality of life. More people were involved after the project started. Roel Bakker of UMCG, section Applied Research/SHARE (formerly the Northern Centre for Healthcare Research), a colleague of Jelte Bouma, joined the project to help with the survey and to publish results. Also, four (former) students from the Faculty of Mathematics and Natural Sciences of RUG have cooperated in this project. Eildert Slim collected information on sound production of wind turbines. Rowan Rossing, just finishing his study, designed a software application that enabled the calculation of visual and aural exposure for the study group from all Dutch wind turbines. At the end of the project Rowan Rossing, at that time a private IT consultant, changed the application so it could be used by others, including members of the public. Jan Oudelaar, who had finished his study recently, was appointed as our GIS expert who did all the selections of turbines and addresses. At the end of the project Lianne Schuiling designed and wrote the text for the website for this project. Both RUG and UGOT have had many contacts with local groups concerned with wind energy. In fact the NKPW, a Dutch acronym for the National Critical Platform on Wind Energy) has asked us to initiate this project. They were informed on the project progress after the two project meetings held in Groningen. 3. Overview of project The project started with a kick-off meeting in Groningen in January Here the survey details were discussed, including a draft of the questionnaire, the method to select the study group and the model to structure the analysis of survey and dose data. The following months were used to produce the questionnaire and to perform the actual study group selection and exposure assessment. In May 2007 the questionnaire was sent to the selected addresses and the complete project database was ready in June 2007, as planned. An originally unexpected but valuable addition to the project database were the detailed Dutch transportation sound levels that could be matched to the respondents addresses, allowing us to compare the impact of different noise sources.

4 WINFDFARMperception Final Activity Report p. 3 The preliminary analysis of the data was performed in the second half of 2007 and the results were collected in working papers that were discussed at the progress meeting in Januari 2008, again in Groningen. The meeting also reviewed the project methodology and forthcoming papers. After that the final analyses were done and documented in an analysis report. This report and parts of the interim reports formed the input for the final report that was published in June Publication of the final report was accompanied by a national (Dutch) and international (English) press statement, a message including a summary of results sent to several wind energy associations, colsultants and wind energy groups, and a popular summary sent to respondents who had expressed an interest to see the results. Also a website with project results was opened. On request of the project partners the project period was extended with two months. Thus we were able to accept the invitation to present the final results at the Acoustics08 conference in Paris. Earlier, preliminary results had been presented at three other conferences (see list of deliverables below). The extension with two months and the remaining budget allowed for more activities not originally planned. The software application to calculate wind farm exposure was made suitable for other users, even allowing lay people to do an assessment. And a student s project led to an expansion of the text on the website, from which also the software application can be downloaded. 4. Study methods The study included calculating the aural and visual exposure at residences due to wind farms, and a postal survey among Dutch residents to measure their response to the actual exposure. The study group was selected from all residents in the Netherlands within 2.5 km from a wind turbine. As the study aimed to address modern wind farms, wind turbines were selected with an electric capacity of 500 kw or more and one or more turbines within 500 m from the first. Excluded were wind turbines that were erected or replaced in the year preceding the survey. Residents lived in the countryside with or without a main road close to the turbines, or in built-up areas (villages, towns). Excluded were residents in mixed and industrial areas.

5 Final Activity Report WINFDFARMperception p. 4 The sound level at the residents dwellings was calculated according to the international ISO standard for sound propagation, the almost identical Dutch legal model and a simple (non spectral) calculation model. The rating sound level used was the sound level when the wind turbines operate at 8 m/s in daytime -that is: at high, but not maximum power. The size of the turbines was calculated as the viewing angle between the lowest and highest part of the biggest turbine, and also as the fraction of space above the horizon occupied by all wind turbines, both from the perspective of residents dwellings. The study group consisted of over addresses. To obtain sufficient statistical reliability balanced against unnecessary work we needed approximately 150 addresses per area type and per sound level class. In the high exposure classes all addresses were used, in each of the low exposure classes 150 were randomly selected. Thus for the survey almost 2000 residential adresses were finally selected and a questionnaire was sent to these adresses. 37% returned the questionnaire. A test amongst those that did not return the questionnaire (the nonrespondents) showed that for two key questions they did not differ from the respondents. The Dutch National Institute for Public Health and the Environment (RIVM) were so kind to supply us with their transportation sound levels for a 25 m by 25 m grid over the entire country of the Netherlands. These data are calculated day-evening-night sound immission levels (L den ) due to road, air and rail traffic, based on traffic volumes in These data were added to the survey database. Later in the project it was shown how to transform our rating sound levels to L den levels, so as to be able to compare the annoyance of sound from the different sources. All questionnaire results were fed into the survey database as well as the sound levels and the visual exposures obtained from the calculation models. This was the material available for analysis. 5. Main study results The project methodology and results have been published on June 3, 2008 in the final report Project WINDFARMperception - Visual and acoustic impact of wind turbine farms on residents. The main results are summarized here.

6 WINFDFARMperception Final Activity Report p. 5 Attitude and economic involvement of respondents Almost all respondents (92%) were satisfied with their living environment, though many reported changes for the better and changes for the worst. One in two respondents were (very) positive towards wind turbines in general, but only one in five were (very) positive towards their impact on the landscape scenery. Fourteen percent of the repondents had economic benefits from wind turbines by owning them or having shares in wind turbines or otherwise. They usually lived closer to the wind turbines, were higher educated, less old and hence healthier compared to the other respondents, and they relatively often worked at home. Respondents with economical benefits were less negative to wind turbines in general and their influence on the landscape scenery. Response to wind turbine sound The percentage of respondents noticing the sound of wind turbines increased with increasing sound level, ranging from 25% at low sound levels (less than 30 dba) to 80% and more at higher sound levels (above 35 dba). Percentages were the same for those who had benefits and the other respondents. The percentage of respondents that were annoyed by the sound also increased with sound level up to 40 to 45 dba and then decreased. Respondents with economic benefits reported almost no annoyance. This in part explains the decrease in annoyance at high sound levels: above 45 dba, i.e. close to wind turbines, the majority of respondents have economical benefits. The percentage of respondents without economic benefits that were rather or very annoyed when outdoors increased from 2% at low levels of wind turbine sound (less than 30 dba) up to 25% at levels of 40 to 45 dba. In general respondents perceived wind turbines as being louder in wind blowing from the turbine to their dwelling (and less loud the other way round), in stronger wind and at night. The majority (75%) of respondents that could hear wind turbines think that swishing or lashing is a correct characterization of the sound. The second most typical characterization was rustling (for 25% of the respondents). Other characterizations were chosen by less than 10% of the respondents.

7 Final Activity Report WINFDFARMperception p. 6 Respondents were more likely to be annoyed by sound from wind turbines when they noted changes for the worse in their living environment and when they had a more negative view on wind turbines in general or their impact on the landscape scenery. Health effects There is no indication that the sound from wind turbines had an effect on respondents health, except for the interruption of sleep. At high levels of wind turbine sound (more than 45 dba) interruption of sleep was more likely than at low levels. Higher levels of background sound from road traffic also increased the odds for interrupted sleep. Annoyance from wind turbine sound was related to difficulties with falling asleep and to higher stress scores. From this study it cannot be concluded whether these health effects are caused by annoyance or vice versa or whether both are related to another factor. Response to other aspects of wind turbines Respondents were also annoyed by wind turbines in other ways than by sound: between 4% and 13% were rather or very annoyed by vibrations or the movement of rotor blades or their shadows in- or outdoors. One out of three respondents could not see a wind turbine from their dwelling, especially when living in a built-up area or further away from the turbines. The visibility of wind turbines strongly affected the probability of being annoyed by their sound: when turbines were visible, respondents were far more likely to be annoyed. An unexpected result was that respondents living in a rural area with a main road within 500 m from the wind turbine(s) were less annoyed than respondents living in a built-up area, though the background sound levels from road traffic are on average the same in both area types and one would expect that wind turbines are more readily visible in a rural area. 6. Recommendations based on the study results Based on the project results a number of recommendations could be proposed in the final report.

8 WINFDFARMperception Final Activity Report p. 7 Sound proved to be the most annoying aspect of wind turbines. From this and previous studies it appears that sound from wind turbines is relatively annoying: at the same sound level it causes more annoyance than sound from air or road traffic. A swishing character is observed by three out of four respondents that can hear the sound and could be one of the factors explaining the annoyance. Sound is therefore an important and negative feature of wind farms and we recommend that, in the planning of wind farms, the negative impact of the sound and sound reduction should be given more attention. Nevertheless, people that have economical benefits from wind turbines are much less or not at all annoyed, even though they often live closer to wind farms and are exposed to higher sound levels. This lack of annoyance may be the result of several factors: e.g. the benefitters have a more positive view on wind farms, they have an actual benefit and they have a measure of control on the turbines. These characteristics may show the way to more acceptance and less annoyance with other residents: residents may be given some benefits and a sense of control too. Discussion of the different views on the landscape, instead of opposition to other views, may help in reaching consensus. Visibility of wind turbines enhances their potential to cause noise annoyance. When wind turbines are invisible, they cause less annoyance. Perhaps less visibility can also be the result of reducing the visual contrast between turbines and landscape. The possibilities to do this will depend on the landscape type. The capability of busy road traffic to mask the sound of wind turbines is apparently not straightforward: a higher level of background sound from road traffic indeed reduces the probability of noticing the sound of wind turbines, but it does not have an effect on annoyance from the wind turbines. This may be due to differences between both sounds in pitch, in character (swishing) and in diurnal variation. This issue needs further investigation. 7. Dissemination of project results The project has yielded a number of products or deliverables. Several final products are publicly available. The interim products served to document the project progress and are not publicly available. The project database, including the survey results and the dose data, also is

9 Final Activity Report WINFDFARMperception p. 8 not publicly available, but researchers who are interested in using the data can contact Eja Pedersen (Eja.Pedersen@hh.se). The main products for public use are the final report describing the results of the project (Deliverable D6) and the software application to calculate the impact of wind farms based on the user s own input data (Deliverable 15). Table 1 gives a summary of all deliverables. The project website gives an overview of the project and its results, in Dutch and in English. Also the report (D6) and the calculation tool (D15), including an exampl eporject and a user manual (both in Dutch and English) can be downloaded from the website. Table 1: list of publicly available deliverables Number Title Nature Target group D4 Conference papers papers presented at four conferences Scientific community, consultants, authorities and wind energy sector D6 Final report report All groups, including general public D7 Website General public and consultants D8 Press statement press statement Media (national and international) D9 Letter of recommendation text Wind energy sector, wind energy groups D10 Popular summary of results text Survey respondents D15 Exposure calculation tool software application General public and consultants

10 WINFDFARMperception Final Activity Report p. 9 In the course of the project the project partners have presented seven papers on exposure to wind turbines and its effects at four conferences. Of these five were directly linked to the project (three of these were agreed on in the (extended) project proposal) and the remaining two were based on other studies. Table 2 lists all papers. Table 2: list of papers delivered at conferneces Conference Paper title (first) author Wind Turbine Wind farm perception - a study on acoustic and visual impact Pedersen Noise 2007, of wind turbines on residents in the Netherlands Lyon Wind profiles over complex terrain * van den Berg Public Health, Groningen SAE Brazil, Florianopolis Acoustics 08, Paris Wind turbines in the Netherlands: effects on health and quality of life Annoyance caused by community noise interaction of sounds from road traffic and wind turbines Wind farm aural and visual impact in the Netherlands Response to wind turbine noise in the Netherlands Criteria for wind farm noise: Lmax and Lden * Bakker Pedersen van den Berg Pedersen van den Berg *: these papers are not based on project results At the close of the project, three papers were in preparation that will be submitted to peer reviewed journals. 9. Impact of the project As usual with results from scientific research it is not easy to gauge or predict its impact on society. In the course of several years a lot of new knowledge on modern wind turbines has become available, in which two of the partners in this project, Eja Pedersen and Frits van den Berg, played a prominent part. This project gives more, and more detailed, information on the impact of wind farms on their environment, which is crucial information in a time when wind energy is boosted to provide a larger part of the energy needed by society, while at the same time opposition to wind farms is growing. The positive attitude towards sustainable energy is not always accompanied by a positive reception of wind farm plans locally and this study helps to explain why that is. The results support an approach were the local community is

11 Final Activity Report WINFDFARMperception p. 10 involved in the planning proces with real influence on the outcome. Also, the results have helped the Dutch government to commission a review of all wind turbine noise exposure studies to obtain a general dose-response curve. 10. Evaluation of the project objectives and results The projects objectives have been met, in our view even better than anticipated. o The project provides valuable new knowledge on the perception of wind turbines by residents; it adds new data to the earlier Swedish studies and it gives more insight in the determinants of attitude to and perception of wind farms. o The project results allows us to evaluate quantitatively human response to sound exposures from wind turbines and the correlation between aural and visual exposure. o The results show quantitatively the relevance of visibility and sound level, and also the relevance of attitude and (economic) benefits on the perception of wind farms by residents. The results help to understand public reaction to a wind farm, and support an approach where the local population is involved in the planning and exploitation of a wind farm. o The addition of transportation noise sources to the database gave us the possibility to compare response to wind turbine sound with response to road traffic sound. Also in a practical way we delivered more than anticipated: o One conference presentation was foreseen, but when the project was completed, the partners had presented seven papers at four conferences in three countries. Of these five were directly linked to the project and two more were related to wind turbine noise. o The software application written for this project could be adapted to allow lay people and professionals to calculate the exposure to wind farms as was done in the project. Lay people will probably be restricted to relatively simple situations (flat countryside, no shielding) or must contact persons with skills to use it in more complex situations. We are grateful that the European Union has allowed us to complete this study.