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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.


Date added:  May 1, 2017
China, Economics, EnvironmentPrint storyE-mail story

Observed impacts of wind farms on local vegetation growth in northern China

Author:  Tang, Bijian; et al.

Abstract:
Wind farms (WFs) can affect the local climate, and local climate change may influence underlying vegetation. Some studies have shown that WFs affect certain aspects of the regional climate, such as temperature and rainfall. However, there is still no evidence to demonstrate whether WFs can affect local vegetation growth, a significant part of the overall assessment of WF effects. In this research, based on the moderate-resolution imaging spectroradiometer vegetation index, productivity and other remote-sensing data from 2003 to 2014, the effects of WFs in the Bashang area of Northern China on vegetation growth and productivity in the summer (June–August) were analyzed. The results showed that: (1) WFs had a significant inhibiting effect on vegetation growth, as demonstrated by decreases in the leaf area index, the enhanced vegetation index, and the normalized difference vegetation index of approximately 14.5%, 14.8%, and 8.9%, respectively, in the 2003–2014 summers. There was also an inhibiting effect of 8.9% on summer gross primary production and 4.0% on annual net primary production coupled with WFs; and (2) the major impact factors might be the changes in temperature and soil moisture: WFs suppressed soil moisture and enhanced water stress in the study area. This research provides significant observational evidence that WFs can inhibit the growth and productivity of the underlying vegetation.

Bijian Tang, Donghai Wu, Xiang Zhao, Tao Zhou, Wenqian Zhao, and Hong Wei
State Key Laboratory of Remote Sensing Science, Beijing Engineering Research Center for Global Land Remote Sensing, College of Remote Sensing Science and Engineering, Faculty of Geographical Science, Beijing Normal University; Joint Center for Global Change Studies (JCGCS), Beijing; State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University;
Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education, Beijing Normal University; and Shaanxi Jinkong Compass Information Service Co., Xi’an, China

Remote Sensing 2017, 9(4), 332; doi: 10.3390/rs9040332

Download original document: “Observed impacts of wind farms on local vegetation growth in northern China”
Download supplemental figures

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Date added:  April 21, 2017
Vermont, WildlifePrint storyE-mail story

Reducing bat fatalities at wind facilities while improving the economic efficiency of operational mitigation

Author:  Martin, Colleen; Arnett, Edward; Stevens, Richard; and Wallace, Mark

Abstract:
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.
DOI: 10.1093/jmammal/gyx005

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Date added:  April 5, 2017
Germany, Health, NoisePrint storyE-mail story

Infraschall – der Bumerang der Energiewende / Infrasound – the boomerang of the energy transition

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. …

Download original document: “Infraschall – der Bumerang der Energiewende / Infrasound – the boomerang of the energy transition”

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Date added:  April 1, 2017
Colorado, Noise, RegulationsPrint storyE-mail story

Independent Infrasonic Investigations: Golden West Wind Facility, El Paso County, CO

Author:  Rand, Robert

Summary:

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.

Download original document: “Independent Infrasonic Investigations: Golden West Wind Facility, El Paso County, CO”


[NWW thanks Friends Against Wind for providing the video.]

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