Resource Library Category: Netherlands (10 items)
Documents presented here are not the product of nor are they necessarily endorsed by National Wind Watch. This resource library is provided to assist anyone wishing to research the issue of industrial wind power and the impacts of its development. The information should be evaluated by each reader to come to their own conclusions about the many areas of debate.
Response to wind turbine noise in the Netherlands
Source: Pedersen, Eja; Bouma, Jelte; Bakker, Roel; van den Berg, Frits
Abstract: A cross-sectional study with the objective to explore the impact of wind turbine noise on people living in the vicinity of wind farms was carried out in the Netherlands in 2007. A postal questionnaire assessing response to environmental exposures in the living area, including wind turbine noise, was answered by 725 respondents (response rate: 37%). Immission levels of wind turbine noise outside the dwelling of each respondent were calculated in accordance with ISO-9613. The risk for being annoyed by wind turbine noise outdoors increased with increasing sound levels (rs = 0.501, n = 708, p<0.001). The risk for annoyance was decreased for respondents who could not see wind turbines from their dwelling and for respondents who benefited economically from the turbines. No statistically significant correlations between immission levels of wind turbine noise and health or well-being were found. However, noise annoyance due to wind turbine noise was associated with stress symptoms, psychological distress and lowered sleep quality.
Halmstad University/School of Business and Engineering (SET)
Proceedings of the 7th European conference on noise control, EURONOISE, June 29th — July 4th, 2008, Paris, France
Wind farm aural and visual impact in the Netherlands
Source: van den Berg, Frits; Pedersen, Eja; Bakker, Roel; Bouma, Jelte
Abstract: The WINDFARMperception project, carried out in 2007/08 in the Netherlands, aimed to explore the impact of wind turbines on people living close to wind farms. The study group was selected in three types of area (countryside, countryside with major road, built up area) by means of a Geographic Information System (GIS). Each selected address was sithin 2.5 km of a wind turbine of at least 500 kW electric power and a similar turbine within 500 m of the first. Aural impact was calculated according to three different sound propagation models: the international ISO-9613 standard, the model legally required in the Netherlands, and a simplified model as in the New Zealand Standard NZS-6808. Visual impact was quantified in two ways: the vertical angle determined by the height of the apparently tallest turbine, and the solid angle determined by all turbines where each turbine was replaced by a vertical rectangle just enclosing the turbine. Immission sound levels from the wind farms at 1948 receiver locations varied from 21 to 54 dB(A), relative size from 0.01% to 30% of the total field of view. Results show that all impact measures are highly correlated with distance to the nearest wind turbine.
Halmstad University/School of Business and Engineering (SET)
Proceedings of the 7th European conference on noise control, EURONOISE, June 29th — July 4th, 2008, Paris, France
Effect of atmospheric stability on wind turbine sound and microphone noise
Source: van den Berg, Frits
Doctoral Thesis, 12 May 2006, University of Groningen, the Netherlands
Godefridus Petrus van den Berg
IV.3 Wind turbine noise perception
There is a distinct audible difference between the night and daytime wind turbine sound at some distance from the turbines. On a summer’s day in a moderate or even strong wind the turbines may only be heard within a few hundred meters and one might wonder why residents should complain of the sound produced by the wind farm. However, in quiet nights the wind farm can be heard at distances of up to several kilometers when the turbines rotate at high speed. In these nights, certainly at distances from 500 to 1000 m from the wind farm, one can hear a low pitched thumping sound with a repetition rate of about once a second (coinciding with the frequency of blades passing a turbine mast), not unlike distant pile driving, superimposed on a constant broad band ‘noisy’ sound. A resident living at 1 km from the nearest turbine says it is the rhythmic character of the sound that attracts attention: beats are clearly audible for some time, then fade away to come back again a little later. A resident living at 2.3 km from the wind farm describes the sound as ‘an endless train’. In daytime these pulses are usually not audible and the sound from the wind farm is less intrusive or even inaudible (especially in strong winds because of the then high ambient sound level).
In the wind farm the turbines are audible for most of the (day and night) time, but the thumping is not evident, although a ‘swishing’ sound — a regular variation in sound level — is readily discernible. Sometimes a rumbling sound can be heard, but it is difficult to assign it, by ear, to a specific turbine or to assess it’s direction.
V.3 Perception of wind turbine sound
In a review of literature on wind turbine sound Pedersen concluded that wind turbine noise was not studied in sufficient detail to be able to draw general conclusions, but that the available studies indicated that at relatively low levels wind turbine sound was more annoying than other sources of community noise such as traffic [Pedersen 2003]. In a field study by Pedersen and Persson-Waye [2004] 8 of 40 respondents living in dwellings with (calculated) maximum outdoor immission levels of 37.5-40.0 dB(A) were very annoyed by the sound, and at levels above 40 dB(A) 9 of 25 respondents were very annoyed. The correlation between sound level (in 2.5 dB classes) and annoyance was significant (p < 0.001). In this field study annoyance was correlated to descriptions of the sound characteristics, most strongly to swishing with a correlation coefficient of 0.72 [Pedersen et al 2004]. A high degree of annoyance is not expected at levels below 40 dB(A), unless the sound has special features such as a low- frequency components or an intermittent character [WHO 2000]. Psychoacoustic characteristics of wind turbine sound have been investigated by Persson-Waye and 0hrstrom in a laboratory setting with naive listeners (students not used to wind turbine sound): the most annoying sound recorded from five different turbines were described as 'swishing', 'lapping' and 'whistling', the least annoying as 'grinding' and 'low frequency' [Persson Waye et al 2002]. People living close to wind turbines, interviewed by Pedersen et al [2004], felt irritated because of the intrusion of the wind turbines in their homes and gardens, especially the swishing sound, the blinking shadows and constant rotation.
Our experience at distances of approx. 700 to 1500 m from the Rhede wind farm, with the turbines rotating at high speed in a clear night and pronounced beating audible, is that the sound resembles distant pile driving. When asked to describe the sound of the turbines in this wind farm, a resident compares it to the surf on a rocky coast. A resident living further away from the wind farm (1200 m) likens the sound to an 'endless train'. Another resident near a set of smaller wind turbines, described the sound as that of a racing rowing boat (where rowers simultaneously draw, also creating a periodic swish). On the website of MAIWAG, a group of citizens from villages near four wind farms in the south of Cumbria (UK), the sound is described as 'an old boot in a tumble dryer', and also as 'Whumph! Whumph! Whumph!' (see text box in section 111.4). Several residents near single wind turbines remarked that the sound often changed to clapping, thumping or beating when night falls: 'like a washing machine'. It is common in all descriptions that there is noise ('like a nearby motorway', 'a 747 constantly taking of) with a periodic fluctuation superimposed. In all cases the sound acquires this more striking character late in the afternoon or at night, especially in clear nights and downwind from a turbine.
Part of the relatively high annoyance level and the characterisation of wind turbine sound as lapping, swishing, clapping or beating may be explained by the increased fluctuation of the sound. Our results in table V.2 show that in a stable atmosphere measured fluctuation levels are 4 to 6 dB for single turbines, and in long term measurements (over many 5 minute periods) near the Rhede wind farm fluctuation levels of approx. 5 dB are common but may reach values up to 9 dB. ...
It can be concluded that, in a stable atmosphere, the fluctuations in modem wind turbine sound can be readily perceived. As yet it is not clear how this relates to possible annoyance. However, the sound can be likened to the rhythmic beat of music: pleasant when the music is appreciated, but distinctly intrusive when the music is unwanted.
The hypothesis that these fluctuations are important, is supported by descriptions of the character of wind turbine sound as 'lapping', 'swishing', 'clapping', 'beating' or 'like the surf'. Those who visit a wind turbine in daytime will usually not hear this and probably not realise that the sound can be rather different in conditions that do not occur in daytime. This may add to the frustration of residents: "Being highly affected by the wind turbines was hard to explain to people who have not had the experiences themselves and the informants felt that they were not being believed" [Pedersen et al 2004]. Persson-Waye et al [2002] observed that, from five recorded different turbine sounds "the more annoying noises were also paid attention to for a longer time". This supported the hypothesis that awareness of the noise and possibly the degree of annoyance depended on the content (or intrusive character) of the sound.
Fluctuations with peak levels of 3-9 dB above a constant level may have effects on sleep quality. The Dutch Health Council [2004] states that "at a given L-night value, the most unfavourable situation in terms of a particular direct biological effect of night-time noise is not, as might be supposed, one characterised by a few loud noise events per night. Rather, the worst scenario involves a number of noise events all of which are roughly 5 dB(A) above the threshold for the effect in question.
Impact of a large-scale offshore wind farm on meteorology
Source: Rooijmans, Pim
Abstract
In this thesis the meteorological effects of a large-scale (9000 km2) offshore wind farm in the North Sea were simulated using the MM5 mesoscale model. The wind farm was simulated by introducing a higher roughness length (0.5 m) in the area of the wind farm. The meteorological effects were examined by comparing model runs with and without wind farm. Turbulent kinetic energy, cloud formation, precipitation and wind speed reduction were studied. Two case studies with westerly flows were performed. The first case study begins at 00 UTC July 1st 2001 and ends at 18 UTC July 3rd 2001. The second is from 00 UTC October 2nd 1999 to 18 UTC October 4th 1999.
The model was evaluated by comparing observational measurements with the model output. This was done at two places near the Dutch coast, de Kooij and Schiphol. Observational values of wind speed, wind direction and temperature were compared using two boundary layer schemes (ETA and MRF). Then these standard runs were compared with two other runs that included the wind farm.
We compared the wind reduction results of the mesoscale model with a conceptual model. The conceptual model is based on a model by Emeis and Frandsen (1993), where the reduction of horizontal wind speed is computed from a balance between a loss of horizontal momentum and replenishment from above by turbulent fluxes. As regards wind reduction calculations the MM5 model yields comparable results as obtained by the Emeis and Frandsen model.
In case 1, where no clouds were present, the model simulated enhanced cloud formation above the wind farm. The second case, which was partly cloudy, showed no significantly cloudiness increase. The rainfall however did show dramatic changes. The Dutch coast received less but large parts of the North Sea more precipitation.
Master Thesis
Pim Rooijmans
Utrecht University
September 2003 – January 2004
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