- Ice shedding danger to walkers and road users. The American Wind Energy Association’s “Wind Energy Siting Handbook” warns at Chapter 5 paragraph 8.1, that moving turbine rotors are liable to accrete heavier quantities of ice than the stationary components. This ice can break off and be “cast some distance” by a moving rotor, (presumably rather like a sling shot). The proposed site is surrounded on three sides by public roads, one of them the A road from Totnes to Dartmouth and Kingsbridge. All parts of the site are within 400m (1300ft) of a road, and this would mean that road users could be at risk. Professor Terry Matilsky of the Department of Physics and Astronomy at Rutgers University, Piscataway, N.J. has published a calculation that for a blade radius of 100 feet and a rotational speed of up to 1 revolution every 3 seconds (about 20 rev/min) ice can be thrown as far as 1700 feet (518m) from the base of the turbine. The calculation is published on the internet. Presumably, if the rotational speed were faster, the ice could be thrown even further.
- Blade throw. Chapter 5 paragraph. 8.2 of the “Wind Energy Siting Handbook” describes how rotor blades can sheer off and be thrown in the same way. It states that many permitting agencies in the US have established minimum required setbacks from residences, public roads and adjacent property lines to provide safety buffers from potential blade throw. These blades can weigh about 6 tons. The towers have also been known to collapse, even in low winds – see internet videos
- Shadow flicker – This is a strobing effect in sunlight when the moving blades are situated between the viewer and the sun, which even closed eyelids may not block out. This effect may distract motorists and, in some people, trigger epileptic fits. It may also cause annoyance to local residents, walkers and local workers. The Minnesota Department of Health (2009), for example, requires a setback distance of at least 10 rotational diameters, assuming flat ground. Greater setback distances may be needed when turbines are set on elevated ridges as the shadows can be cast over distances of several kilometres. The three public roads surrounding the site are all much closer to the most distant parts of the site than this.
- Low frequency sound issues – effects upon health. Studies by World Health Organisation 2004 and 2007 and the National Research Council, Washington DC, inter alia, list several adverse health effects from low frequency noise, including sleep disturbance, headaches, stress and tinnitus. Low frequency noise travels much greater distances than higher frequencies do. The noise does not need to be consciously perceived as loud for these effects to be produced, nor is the position improved indoors. A NASA technical paper (1990) states “that people inside buildings may actually be more disturbed by the [wind turbine] noise than they would be outside…. One of the common ways that a person might sense the noise-induced excitation of a house is through structural vibrations. This mode of observation is particularly significant at low frequencies, below the threshold of normal hearing
- Effects upon local airfields, gliders and ballooning businesses and military aircraft and radar also need to be considered.
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