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Perceptual Studies of Windfarms
A literature search on studies investigating the visual impact of wind farm developments revealed that most of these studies have been carried out in Denmark and USA. To date, no attempt has been made to develop visual impact models for wind farms.
These studies mainly concentrated on:
Thayer and Freeman (1987) identified a study (Wagstaff Brady Associates, 1982) which investigated the potential impact of wind farm developments in San Gorgonio Pass USA, using basic wire-frame simulations and expert judgements to evaluate the visual absorption capacity of the landscape. The study recommended that in order to reduce potential impact, restrictions had to be imposed on hillside development, clustering similar wind machines; establishing 'free zones' separating clusters, setting back turbines from highways and siting unusually shaped machines in relation to dramatic landforms.
Wolsink and van de Wardt (1989) cited van de Wardt and Staats's (1988) study which used semantic differentials to investigate the impact of wind turbines on scenic quality in Holland. The latter's study concluded that the strongest influence was caused by the number of visible wind turbines in the landscape, i.e. the greater the number the greater the intrusion. The effect of the size of wind turbines: 1MW (50m high and rotor diameter) and 200kW (30m high and 24m rotor diameter) was also considered. The study found that smaller turbines have less negative impact on the landscape than larger turbines. But the influence of size was found to be relatively small compared with the influence of the number of units. Using principal component analysis on the semantic differentials, the authors found a latent dimension of perception: landscape coherence. The negative influence of the 'introduction and the number of turbines' was attributed to a "decrease in coherence of the landscape" and consequently a decrease in people's scenic preference of scenic quality. This is consistent with studies by Kaplans which have found that coherence is directly related to preference.
Part of Thayer and Freeman's (1987) investigation into observer attitudes, symbolic or connotative meanings of wind energy developments found that people tend to prefer fewer larger turbines to more smaller ones. The finding supports van de Wardt and Staats's (1988) conclusion that number of turbines have greater effect on landscape quality than size of turbines. For similar reasons, the Scottish Office's (1993) planning advice on wind farms also favoured the installation of fewer larger turbines.
The number of structures in the landscape has also been found to be important determinants in studies previously described in Chapter 5 (Hadrian et al., 1988 - transmission pylons; Vining et al., 1984 - density of residential houses).
van de Wardt and Staats's (1988) study also identified that the placement pattern of wind turbines influenced preference. In their study, three placement patterns were considered (rectangular, multiple clusters and lines). Although the result from this study was not conclusive, placement of wind turbines in a line were rated more favourably than clusters or rectangular placements. Ferber's (cited in Thayer and Freeman, 1987) study of student reactions to photographic simulations of different single windmill in same landscape settings found that only traditional Dutch windmill attracted positive responses. All other modern turbines were judged to have neutral or negative impact on the landscapes.
Motion has also been indicated as powerful predictor of preference (Gipe, 1993; Thayer and Freeman, 1987). This is a unique feature of wind turbines in comparison to other forms of static structures. People find wind farms that appear to be working by relating this with moving rotors as more attractive than those that do not. Motion is equated with lower perceived visual impact (Gipe, 1993). They are likely to find wind farms visually interesting because of their motion. In this mode, the turbines are perceived as abstract sculptures, arousing interest with their novel, unfamiliar forms and animation (Thayer and Hansen, 1988). Although the motion of wind turbines can be simulated using computer-generated animation it is hardly ever used in the investigation of visual impact. The simulation techniques are complicated and require large amount of computer hard disc space and processing speed to achieve realistic animation. Because of the above difficulties, static simulations were considered to be much more pragmatic.
Thayer and Freeman's (1987) study on public's perception of wind turbines in Altamont Pass, California found subjects who live in and around Altamont or are familiar with the area held less positive views than those who live outside or are not familiar the area. In addition, the study found females, older subjects, and subjects with less education showed more positive attitude towards wind farms. On the other hand, males, younger subjects and those with higher education showed less positive attitude.
Collett's (1995) review of several public opinion surveys carried out in the UK indicated that visual impact of wind turbines are perceived to be less intrusive then generally anticipated. The author concluded that despite concern about the visual intrusion of wind farm developments, most of the local people surveyed held favourable views of its development.
Bergsjo, A., Nilsson, K., and Skarback, E. (1982) Wind power in the landscape. Fourth Symposium on Wind Energy Systems, Stockholm, Sweden, 21-24 September, Paper N2.
Collett, S. (1995). Wind farms and public opinion. NEW Review, The Magazine of New and Renewable Energy, Issue 25, May, p. 14-15
Ferber, R. (1977). Public reactions to wind energy devices. National Science Foundation and US Dept. of Energy, October.
Gipe, P. (1993) The wind industry's experience with aesthetic criticism. Leonardo, 26, 243-248.
Hadrian, D.R., Bishop, I.D. and Mitcheltree, R. (1988) Automated mapping of visual impacts in utility corridors. Landscape and Urban Planning, 16, 261-283.
Scottish Office (1993) National Planning Policy Guideline: renewable energy. Planning Advice Note (Draft).
Thayer, R.L. and Freeman, C.M. (1987) Altamount: public perception of a wind energy landscape. Landscape and Urban Planning, 14, 379-398.
Thayer, R.L. and Hansen, H. (1988) Wind on the land. Landscape Architecture.
van de Wardt, J.W. and Staats, H. (translation) (1988) Landscapes with wind turbines: environmental psychological research on the consequences of wind energy on scenic beauty. Research Centre ROV Leiden University.
Vining, J., Daniel, T.C. and Schroeder, H.W. (1984) Predicting scenic values in forested residential landscapes. Journal of Leisure Research, Second Quarter, 124-135.
Wolsink, M. (1989) Attitudes, expectancies and values about wind turbines and wind farms. EWEC, Glasgow.
Wolsink, M. and van de Wardt, J.W. (1989) Visual impact assessment: a review of Dutch research. EWEC, Galsgow.
Wolsink, M. (1990) The siting problem - wind power as a social dilemma. EWEC, Glasgow.