Re: Proposed wind turbines would be significantly taller (Chatham Daily News, Feb. 6)
In this news item, Adam Rosso, Otter Creek Wind Farm’s director of development states the larger turbines were selected to “effectively reduce the use of the number of turbines…. due to public concerns.”
But unless the Otter Creek developers cancel the remaining unused land leases, there is the inevitable public perception that this decision has more to do with having unused sites available for future expansion than it does with the public’s concerns. I would ask that Mr. Russo clarify if the unused leases have been cancelled.
He claims that “using fewer turbines it will reduce the visual impact”, but doesn’t take into account the turbines’ larger size, that will make them visible from a much greater distance and amplify the visual pollution. Think of this: The tallest office building in Ontario, outside of Toronto and Ottawa, is One London Place in London; it is 113 metres tall. The 12 Otter Creek turbines, at 195 metres, will be almost twice as tall. For some, the visual pollution will be insufferable.
Mr. Russo also states that even though the proposed Otter Creek turbines are taller and have a larger diameter, they “won’t be louder due to less rotational speed.”
What he has missed is that the larger rotor diameter of the Enercon turbines results in faster speed at the blade tips at any given rpm. At their maximum rotation of 10.5 rpm, the Enercon blade tips travel at a speed of 276 km/h. By comparison the blade tips on the smaller Siemens SWT-2.3 turbine travel at a speed of 252 km at their maximum rotation of 13.5 rpm.
The blade tip speed, not the rpm, determines the level of aerodynamic noise, sometimes called “blade swoosh”, which is the most common type of noise pollution from wind turbines encountered by nearby residents.
The greater rotor diameter also makes these turbines more likely to encounter wind shear, a difference in wind speed from the top of rotation at to the bottom, something that also increases aerodynamic noise.
In addition, it has been well documented that as turbines get larger, their noise output is shifted towards the lower frequencies. In its report “Guidelines for Community Noise” the World Health Organization has acknowledged that lower frequency noise is more disturbing to nearby residents.
The Otter Creek developers thus far seem unconcerned about well water quality and now they’re downplaying the potential noise and visual pollution their turbines will bring to the area.
This is not an auspicious start for the Otter Creek project.
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