Resource Documents — latest additions
Documents presented here are not the product of nor are they necessarily endorsed by National Wind Watch. These resource documents are 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.
Author: Gwak, Doo Young; et al.
Wind turbine noise is considered to be easily detectable and highly annoying at relatively lower sound levels than other noise sources. Many previous studies attributed this characteristic to amplitude modulation. However, it is unclear whether amplitude modulation is the main cause of these properties of wind turbine noise. Therefore, the aim of the current study is to identify the relationship between amplitude modulation and these two properties of wind turbine noise. For this investigation, two experiments were conducted. In the first experiment, 12 participants determined the detection thresholds of six target sounds in the presence of background noise. In the second experiment, 12 participants matched the loudness of modified sounds without amplitude modulation to that of target sounds with amplitude modulation. The results showed that the detection threshold was lowered as the modulation depth increased; additionally, sounds with amplitude modulation had higher subjective loudness than those without amplitude modulation.
Kiseop Yoon, Doo Young Gwak, Yeolwan Seong, Seunghoon Lee, Jiyoung Hong, and Soogab Lee
Journal of Mechanical Science and Technology
October 2016, Volume 30, Issue 10, pp 4503–4509
Kiseop Yoon is a Ph.D. student in the Department of Mechanical and Aerospace Engineering at Seoul National University. He received his B.S. degree from the School of Mechanical and Aerospace Engineering at Seoul National University in 2011. His research interests are in the area of active noise control system and the perception of environmental noise.
Doo Young Gwak is a Ph.D. student in the Department of Mechanical and Aerospace Engineering at Seoul National University. He received his B.S. degree from the School of Mechanical and Aerospace Engineering at Seoul National University in 2010. His research interests are in the area of psychoacoustics and the prediction of ‘drone’ noise.
Yeolwan Seong is a Researcher in the Defense Agency for Technology and Quality at Daejeon. He received his M.S. degree from the School of Mechanical and Aerospace Engineering at Seoul National University in 2013. His research interests are in the area of psychoacoustics and railway noise.
Seunghoon Lee is a Researcher in the Korea Aerospace Research Institute at Daejeon. He received his Ph.D. degree from the School of Mechanical and Aerospace Engineering at Seoul National University in 2014. His research interests are in the area of helicopter aerodynamics and wind turbine noise.
Jiyoung Hong is a Researcher in the Korea Railroad Research Institute at Uiwang. She received her Ph.D. degree from the School of Mechanical and Aerospace Engineering at Seoul National University in 2011. Her research interests are in the area of human noise perception and environmental noise impact assessment.
Soogab Lee is a Professor in the Department of Mechanical and Aerospace Engineering at Seoul National University. He received his Ph.D. in Aeronautics and Astronautics from Stanford University in 1992. He worked as a Research Scientist at NASA Ames Research Center from 1992 to 1995. His research interests are in the area of aerodynamics and acoustics of rotating machines including wind turbine systems.
Author: Smith, Michael; Ögren, Mikael; Thorsson, Pontus; Pedersen, Eja; and Persson Waye, Kerstin
In accordance with the EU energy policy, wind turbines are becoming increasingly widespread throughout Europe, and this trend is expected to continue globally. More people will consequently live close to wind turbines in the future, and hence may be exposed to wind farm noise. Of particular concern is the potential for nocturnal noise to contribute towards sleep disturbance of nearby residents. To examine the issue, we are implementing a project titled Wind Turbine Noise Effects on Sleep (WiTNES). In a pilot study described in this paper, we performed an initial investigation into the particular acoustical characteristics of wind turbine noise that might have the potential to disturb sleep. Six young, healthy individuals spent 5 nights in our sound exposure laboratory. During the final 3 nights of the study, the participants were exposed to wind turbine noise, which was synthesised based on analysis of field measurements. Exposures involved periods of different amplitude modulation strengths, the presence or absence of beats, different blade rotational periods, and outdoor LAEq,8h=45 or 50 dB with indoor levels based on the windows being fully closed or slightly open. Physiological measurements indicate that nights with low frequency band amplitude modulation and LAEq,8h=45 dB, slightly open window (LAEq,8h=33 dB indoors) impacted sleep the most. The presence of beats and strong amplitude modulation contributed to sleep disturbance, reflected by more electrophysiological awakenings, increased light sleep and wakefulness, and reduced REM and deep sleep. The impact on sleep by these acoustic characteristics is currently the focus of interest in ongoing studies.
Michael G. Smith, Mikael Ögren, Pontus Thorsson, Eja Pedersen, and Kerstin Persson Waye
University of Gothenburg, Sweden (MGS, MÖ, KPW).
Chalmers University of Technology Sweden (PT).
Lund University, Sweden (EP).
Presented at the 22nd International Congress on Acoustics, Buenos Aires, 5–9 September 2016
Wind speed reductions by large-scale wind turbine deployments lower turbine efficiencies and set low generation limits
Author: Miller, Lee; and Kleidon, Axel
Wind turbines generate electricity by removing kinetic energy from the atmosphere. Large numbers of wind turbines are likely to reduce wind speeds, which lowers estimates of electricity generation from what would be presumed from unaffected conditions. Here, we test how well wind power limits that account for this effect can be estimated without explicitly simulating atmospheric dynamics. We first use simulations with an atmospheric general circulation model (GCM) that explicitly simulates the effects of wind turbines to derive wind power limits (GCM estimate), and compare them to a simple approach derived from the climatological conditions without turbines [vertical kinetic energy (VKE) estimate]. On land, we find strong agreement between the VKE and GCM estimates with respect to electricity generation rates (0.32 and 0.37 We m−2) and wind speed reductions by 42 and 44%. Over ocean, the GCM estimate is about twice the VKE estimate (0.59 and 0.29 We m−2) and yet with comparable wind speed reductions (50 and 42%). We then show that this bias can be corrected by modifying the downward momentum flux to the surface. Thus, large-scale limits to wind power use can be derived from climatological conditions without explicitly simulating atmospheric dynamics. Consistent with the GCM simulations, the approach estimates that only comparatively few land areas are suitable to generate more than 1 We m−2 of electricity and that larger deployment scales are likely to reduce the expected electricity generation rate of each turbine. We conclude that these atmospheric effects are relevant for planning the future expansion of wind power.
Lee M. Miller and Axel Kleidon
Biospheric Theory and Modelling, Max Planck Institute for Biogeochemistry, Jena, Germany
Author: Crawford, Michael
The substantial body of empirical research now available on wind farm visual impact (VI), from
very credible and impartial teams, shows a consistent and essentially linear relationship between
turbine height, distance and wind farm VI. For any degree of VI (such as the zone of visual
influence, or threshold for visual dominance), if turbine height is doubled, the distance threshold
for that degree of impact also typically doubles.
The research based distances for thresholds for key levels of VI are many times larger than
thresholds proposed by the NSW Department of Planning and Environment in its draft VI
Assessment Bulletin. The Department’s proposed thresholds are repudiated by the consistent
The research also identifies a number of other ways in which wind farm VI assessment practices
accepted by NSW planning agencies are defective, in particular relating to the neglected
importance of blade movement for VI, the fact that photomontages tend systematically to
underestimate VI, and the assessment frameworks commonly used are too simplistic to describe
real world experience.
The NSW Government has a responsibility to reassess its draft VI Assessment Bulletin explicitly in
the context of the published research and produce proposals which it can intellectually justify in the
context of that research – which at present it cannot do.
[ABSTRACT; 6th November 2016]