“Wind farm could keep people awake at night” – but Navitus Bay directors say turbines will not breach noise levels (From Bournemouth Echo)
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“Wind farm could keep people awake at night” – but Navitus Bay directors say turbines will not breach noise levels
THE planned wind farm in Poole Bay could keep people awake at night across Bournemouth and Poole, according to an acoustics expert.
John Yelland said the noise from the massed turbines of the Navitus Bay wind park would likely exceed the government recommended limit along the coastline.
The physicist and engineer said the firm had failed to properly take into account the effects of wind shear – the increase in wind speed with height above ground – and the reflection of sound off the sea.
“The noise isn’t likely to be heard by the man on the street, if there is a problem it will affect people trying to sleep,” he said.
“The wind shear effect is at its maximum in the night, and background noise is low then too.
“It could be a problem for people trying to sleep.
“I support offshore wind farms but not when they are too close to people’s homes.”
Dr Yelland, who lives near Newport on the Isle of Wight, is a fellow of the Institute of Engineering and Technology, a member of the Institute of Physics and a member of the Institute of Acoustics.
Navitus Bay project director Mike Unsworth said the firm employed recognised industry standards to assess the potential noise impact, and had concluded that the turbines would not exceed the threshold recommended by the Institute of Acoustics.
“These standards have been employed for assessing potential noise impacts for many offshore wind farm schemes around the UK, many of which are located much closer to shore than the proposed development,” he said.
“In fact, of the 22 operational offshore wind projects in the UK, 16 are closer to shore.”
The Navitus project, with a maximum of 218 wind turbines up to 200m high, has already attracted opposition for its appearance and fears over its possible impact on tourism, bird populations, and navigation.
However, it has received support for its potential contribution to reducing the UK’s energy dependency and carbon footprint.
Angela Pooley, from East Dorset Friends of the Earth, said: “Even if this was the case we think it is a very minor issue and people should focus on the big picture, we need renewable energy.”
The science of sound
The Navitus Bay environmental report claims the turbines act as “spherical point sources”, so the noise they create travels in all directions, reduced by six decibels per doubling of distance.
However, Dr Yelland believes the effects of wind shear and reflection mean a “cylindrical” pattern of noise propagation is more appropriate.
By this measure the sound would travel further and be reduced by only three decibels per doubling of distance, meaning noise levels would exceed the 35 decibel maximum at detectors more than 12 miles away on-shore.
“This is not new information, a lot of work has been done on offshore wind farm acoustics by the Swedish Royal Institute of Technology, commissioned by their government,” said Dr Yelland.
He said he had seen errors made by wind developers in their noise calculations and was “appalled by their academic standards”.
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