Posts Tagged ‘wind turbines’

Bats attracted to wind turbines because they think they are tall trees?

October 26, 2014

A new study published in PNAS has used thermal imaging to test the the hypotheses that wind speed and blade rotation speed influenced the way that bats interacted with turbines.  They found that the air currents around slow speed turbines could be fooling the bats into thinking they were the air currents associated with tall trees. It is suggested that around trees the air currents led to the bats searching for roosts and nocturnal insect prey that could accumulate in such air flows. Thus bat behaviour which had evolved as being advantageous around tall trees might now be the reason why many bats die at wind turbines.

“Fatalities of tree bats at turbines may be the consequence of behaviors that evolved to provide selective advantages when elicited by tall trees, but are now maladaptive when elicited by wind turbines”.

Paul Cryan et al, Behavior of bats at wind turbines, PNAS, Vol. 111 no. 42,  15126–15131, doi: 10.1073/pnas.1406672111


Bats are dying in unprecedented numbers at wind turbines, but causes of their susceptibility are unknown. Fatalities peak during low-wind conditions in late summer and autumn and primarily involve species that evolved to roost in trees. Common behaviors of “tree bats” might put them at risk, yet the difficulty of observing high-flying nocturnal animals has limited our understanding of their behaviors around tall structures. We used thermal surveillance cameras for, to our knowledge, the first time to observe behaviors of bats at experimentally manipulated wind turbines over several months. We discovered previously undescribed patterns in the ways bats approach and interact with turbines, suggesting behaviors that evolved at tall trees might be the reason why many bats die at wind turbines.

Fig. 1.

Fig. 1 Still images of night-flying bats (green arrows) at wind turbines that were detected in thermal-infrared video footage. Cameras were positioned 12 m from the base of the turbine, looking up the 80-m monopole toward the nacelle (rectangular machinery enclosure) and rotor, to which three 40-m blades attach. Red circles represent the object identified as a bat by the automated software used for finding their presence in nightly (∼10 h) video recordings. A variety of detection conditions are illustrated, including a bat approaching fast-rotating (14 rpm) …


Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012, using thermal cameras and other methods. We observed bats on 993 occasions and saw many behaviors, including close approaches, flight loops and dives, hovering, and chases. Most bats altered course toward turbines during observation. Based on these new observations, we tested the hypotheses that wind speed and blade rotation speed influenced the way that bats interacted with turbines. We found that bats were detected more frequently at lower wind speeds and typically approached turbines on the leeward (downwind) side. The proportion of leeward approaches increased with wind speed when blades were prevented from turning, yet decreased when blades could turn. Bats were observed more frequently at turbines on moonlit nights. Taken together, these observations suggest that bats may orient toward turbines by sensing air currents and using vision, and that air turbulence caused by fast-moving blades creates conditions that are less attractive to bats passing in close proximity. Tree bats may respond to streams of air flowing downwind from trees at night while searching for roosts, conspecifics, and nocturnal insect prey that could accumulate in such flows. Fatalities of tree bats at turbines may be the consequence of behaviors that evolved to provide selective advantages when elicited by tall trees, but are now maladaptive when elicited by wind turbines.


Wind turbine vibrations causing development deformities in foals?

September 26, 2013

This is from a Masters thesis at the Veterinary Medicine Faculty of the Universidade Tecnica de Lisboa by Teresa Margarida Pereira Costa e Curto. The study reports the findings from a stud where 11 foals developed flexural deformities of the front limbs, after they were born. (Acquired flexural deformity of the distal interphalangeal joint). In 2008, wind turbines were installed adjacent to the property and grazing paddocks. Since this date, a good number of foals and yearlings have developed deformities.  The hypothesis is that ground vibrations induced by the wind turbines are enhancing bone growth in young foals but without a corresponding enhancement of the muscle-tendon growth leading to the deformation.

From Turn180:

The study was performed by Teresa Margarida Pereira Costa e Curto,  ADVISOR: Dr. Maria da Conceição da Cunha and Vasconcelos Peleteiro CO-ADVISOR: Dr. Maria Luisa Jorge Mendes

The above image shows the same foal at 3 and 6 months of age

Final deformity

Radiological examination of front limbs

In this stud farm, the owner has been breeding normal and physically sound horses since 2000. There were no changes in diet, exercise or any other significant alteration in management. Until in 2008, wind turbines were installed adjacent to the property and grazing paddocks. Since this date, a good number of foals and yearlings have developed deformities.

The subjects of the study were:
-11 Lusitano horses. Age between 0 and 48 months old.
-6 males and 5 females
-9 were born at the stud farm,  2 were acquired from a different breeder.

Measurements of ground vibration were made at different distances from the wind turbines, with the same equipment that is used to detect seismic vibrations (earthquakes). The results of these measurements, showed ground vibration at different frequencies.
Research has shown that vibration effects bone metabolism.

Cellular Mechanotransduction is the mechanism by which cells convert mechanical signals into biochemical responses. Based on the mechanical effects on cells it was proposed in this research project that the ground vibrations were responsible for a increased bone growth which was not accompanied by the muscle-tendon unit growth leading to the development of these flexural deformities.


The above research project was based solely on this case study. Therefore, further research is necessary in order to validate these preliminary findings and hypothesis. Regarding the sound that the wind turbines produce, measurements were taken and studies have demonstrated some cellular damage is caused by low frequency noise.

RESEARCH TITLE:             Acquired flexural deformity of the distal interphalangic joint in foals

Since 2008, a high prevalence of front limb acquired flexural deformities was observed in a Lusitano stud farm. This work aims to evaluate this problem by reporting the results from tissue alterations in the affected animals as well as environmental conditions and management changes, which could have led to this observation. A total of eleven affected animals were studied. In these, a complete physical and orthopaedic examination were performed specifically the determination of the angle between the dorsal hoof wall and the floor. Radiographic examination, CT imaging, determination of the thickness of the cortical bone of the third metacarpian and histopathology of some tissues collected in biopsy and necropsy were done in a subset of affected foals.

All the animals had been supplemented with balanced commercial diet for equine. To investigate a possible genetic cause, two foals from distinct bloodlines were brought to the stud. These also developed the deformities after 6 months. Two of the affected foals were placed in a
pasture away from the initial one and two others were admitted at the Faculty of Veterinary Medicine of Lisbon. In those animals, except for one that had to be euthanized for humane reasons, an improvement was observed on their condition, with partial recovery of the deformity.
Histopathology was performed from (i) the tendon obtained by surgical desmotomy in one foal, (ii) tendon biopsies were performed in three foals and (iii) from the tissue of one foal during necropsy. Histologically the most significant alterations were the dissociation of myofibrils of the smooth muscle. This was predominantly seen in the small intestine but also in the walls of small capillary vessels, including those of the tendon vasculature. The flexural deformities have a complex and multifactorial etiopathogeny. They occur due to uncoupling of the longitudinal development of the bone and its adjacent soft tissues, but also from shortening of the tendon-muscle unit in response to pain.
In the case series presented here, there was no obvious cause for the development of this problem, therefore we hypothesised that unusual environmental conditions might have played an important role in the development of this condition, especially those introduced in recent years.

Retired High Court judge accuses Danish government of corruption over wind turbines

November 21, 2012

The Danish love of wind turbines  – sometimes bordering on the irrational – is well known. That is also why they have the highest prices for electricity in Europe. That Denmark is also considered one of the least corrupt countries in the world is taken for granted. But apparently things are not always what they seem. The Copenhagen Post carries a remarkable article by Peter Rørdam, a retired High Court judge which offers a peek behind the scenes at chicanery in the wind industry/government nexus. The article is reproduced below:

The Copenhagen Post

The myth of Denmark as a corruption-free country

It’s a widely held conception that Denmark is one of the world’s least corrupt countries. The message is always warmly received, but this isn’t the same as saying that Denmark is free of corruption.


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