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.
Reducing bat fatalities at wind facilities while improving the economic efficiency of operational mitigation
Author: Martin, Colleen; Arnett, Edward; Stevens, Richard; and Wallace, Mark
Concerns about cumulative population-level effects of bat fatalities at wind facilities have led to mitigation strategies to reduce turbine-related bat mortality. Operational mitigation that limits operation may reduce fatalities but also limits energy production. We incorporated both temperature and wind speed into an operational mitigation design fine-tuned to conditions when bats are most active in order to improve economic efficiency of mitigation. We conducted a 2-year study at the Sheffield Wind Facility in Sheffield, Vermont. Activity of bats is highest when winds speeds are low (< 6.0 m/s) and, in our region, when temperatures are above 9.5°C. We tested for a reduction in bat mortality when cut-in speed at treatment turbines was raised from 4.0 to 6.0 m/s whenever nightly wind speeds were < 6.0 m/s and temperatures were > 9.5°C. Mortalities at fully operational turbines were 1.52–4.45 times higher than at treatment turbines. During late spring and early fall, when overnight temperatures generally fell below 9.5°C, incorporating temperature into the operational mitigation design decreased energy losses by 18%. Energy lost from implementation of our design was < 3% for the study season and approximately 1% for the entire year. We recommend that operational mitigation be implemented during high-risk periods to minimize bat fatalities and reduce the probability of long-term population-level effects on bats.
Colleen M. Martin
Richard D. Stevens
Mark C. Wallace
Department of Natural Resources Management, Texas Tech University, Lubbock
Edward B. Arnett
Theodore Roosevelt Conservation Partnership, Loveland, Colorado
Published: 10 March 2017
Journal of Mammalogy (2017) 98 (2): 378-385.
Author: Stiller, Thomas
“Ich fühle, was Du nicht hören kannst.” So beschreiben Anwohner gerade von Windkraftanlagen oft ihre Beschwerden, ausgelöst durch niederfrequente Geräusche (Infraschall). Aber was ist die Ursache von Infraschall, welche Auswirkungen hat er auf Menschen, welche Normen regeln die erlaubten Schallemissionen und was ist der Stand der Wissenschaft auf diese Fragen? … Die niederfrequenten Schwingungen aus Kompressoren und Windkraftanlagen erzeugen bei diesen Menschen Stressreaktionen, die sich u.a. in Schlafstörungen, Konzentrationsstörungen, Übelkeit, Tinnitus, Sehstörungen, Schwindel, Herzrhythmusstörungen, Müdigkeit, Depressionen und Angsterkrankungen, Ohrenschmerzen und dauerhaften Hörstörungen äußern.
Inaudible but biophysiologically effective sound is not science fiction but an increasing threat to health. First, a few physical bases: sound is the pressure change in a medium such as air and spreads around the source. The lower the frequency, the more sound is transported in the air. Very low frequencies are also transmitted through closed buildings. As a result of acoustic reflections and superimpositions, it can then lead to excessively high sound pressure values. In general, sounds and noises are described by frequency, timbre and volume. The human ear can hear frequencies approximately in the range of 20,000 Hz, i.e., vibrations per second (high tones) to 20 Hz (low tones). The sound range above a frequency of 20,000 Hz is referred to as ultrasound, below 200 Hz as low-frequency sound, below 20 Hz as infrasound. Both infrasound and ultrasound are no longer perceived by the ear, but the body has a subtle perception for infrasound, and some people are particularly sensitive to low-frequency sound.
In nature, low-frequency vibrations are ubiquitous. For example, some migratory birds orient themselves by the noise of the sea which is transmitted over several hundred kilometres in the atmosphere. The infrasound from wind turbines is still measurable for several kilometres. …
About 10-30 percent of the population is sensitive to infrasound radiation. These people, which in Germany number several million, develop numerous symptoms, which are now understood by more and more physicians. The low-frequency oscillations from compressors and wind power plants cause stress reactions in these people, which manifest themselves in sleep disorders, concentration disorders, nausea, tinnitus, dysphasia, dizziness, cardiac arrhythmia, fatigue, depression and anxiety disorders, earaches and permanent hearing impairments. …
Author: Rand, Robert
Differential acoustic pressure measurements were acquired and logged at three homes in the vicinity of the Golden West Wind Facility in El Paso County, Colorado during December 2015 and January 2016. A week of data was analyzed for each of the three homes and daily spectrograms produced which are attached. Each day’s data consisted of approximately 4.3 million differential pressure samples with a week comprised of some 30.5 million samples.
Preliminary investigation confirmed the presence of recurring acoustic pressure oscillations at 0.2 to 0.85 Hz (the “blade pass frequency” or BPF) which are associated to the Golden West wind turbine rotations. At times multiple oscillation frequencies were observed, consistent with multiple turbines operating at different rotation rates. Oscillations appeared to be more pronounced when the turbines are more upwind rather than downwind. Neighbors reported they are mostly downwind due to turbine location relative to home location and for the prevailing winds in the region.
Typical BPF total acoustic power were computed for example portions of the differential pressure data sets. Crest factors (the ratio of RMS to peak levels) were also computed for segments dominated by wind turbine rotation and uncontaminated by other noise, with typical crest factors of 13-19 dB. Totalized BPF RMS levels ranged from 56 to 70 dB re 20uPA, with peak levels from 71 to 89 dB. The RMS and peak levels are similar to those found at other sites with appeals to stop the noise, legal action, and homes abandoned.
It is understood from neighbors that they have experienced disturbance since the turbines started operating whereas prior to turbine operation there was no similar disturbance. It is understood that neighbors report improvement when turbines are shut down (not rotating) or when they remove themselves physically away from the Facility a distance of several miles.
El Paso County noise regulations define “Sound” as oscillations in pressure (or other physical parameter) at any frequency, and, prohibits noise disturbance due to acoustic oscillations.
The analysis is far from complete in that numerous segments of each day at each monitoring location could be analyzed and associated to journal entries and/or medical data. The reported association of proximity to the operating facility to disturbance in health and quality of life appears supported by the acoustic data acquired for this preliminary investigation. These preliminary investigations suggest that there is a condition of noise disturbance due to very low frequency acoustic pressure oscillations in the vicinity of the Golden West Wind Facility when it is operating, with more severe impacts downwind.
[NWW thanks Friends Against Wind for providing the video.]
Author: Graff, Brianna; et al.
ABSTRACT: The Northern Great Plains (NGP) contains much of the remaining temperate grasslands, an ecosystem that is one of the most converted and least protected in the world. Within the NGP, the Prairie Pothole Region (PPR) provides important habitat for >50% of North America’s breeding waterfowl and many species of shorebirds, waterbirds, and grassland songbirds. This region also has high wind energy potential, but the effects of wind energy developments on migratory and resident bird and bat populations in the NGP remains understudied. This is troubling considering >2,200 wind turbines are actively generating power in the region and numerous wind energy projects have been proposed for development in the future. Our objectives were to estimate avian and bat fatality rates for wind turbines situated in cropland- and grassland-dominated landscapes, document species at high risk to direct mortality, and assess the influence of habitat variables on waterfowl mortality at 2 wind farms in the NGP. From 10 March to 7 June 2013–2014, we completed 2,398 searches around turbines for carcasses at the Tatanka Wind Farm (TAWF) and the Edgeley-Kulm Wind Farm (EKWF) in South Dakota and North Dakota. During spring, we found 92 turbine-related mortalities comprising 33 species and documented a greater diversity of species (n = 30) killed at TAWF (predominately grassland) than at EKWF (n = 9; predominately agricultural fields). After accounting for detection rates, we estimated spring mortality of 1.86 (SE = 0.22) deaths/megawatt (MW) at TAWF and 2.55 (SE = 0.51) deaths/MW at EKWF. Waterfowl spring (Mar–Jun) fatality rates were 0.79 (SE = 0.11) and 0.91 (SE = 0.10) deaths/MW at TAWF and EKWF, respectively. Our results suggest that future wind facility siting decisions consider avoiding grassland habitats and locate turbines in preexisting fragmented and converted habitat outside of high densities of breeding waterfowl and major migration corridors.
BRIANNA J. GRAFF, JONATHAN A. JENKS, JOSHUA D. STAFFORD, KENT C. JENSEN, and TROY W. GROVENBURG
Department of Natural Resource Management, South Dakota State University, and South Dakota Cooperative Fish and Wildlife Research Unit, US Geological Survey, Brookings, SD, USA
The Journal of Wildlife Management 80(4):736–745; 2016; DOI: 10.1002/jwmg.1051