Underwater Acoustic EIA Modelling

DP Energy required an underwater Environmental Impact Assessment (EIA) in order to be granted planning consent for a 30MW marine tidal turbine array off the west coast of Islay in Scotland. Regulatory body, Marine
Scotland, have to be assured that impacts of marine life such as behavioural
response, collision risk and chance of injury have been appropriately
assessed. As tidal turbines are a relatively new technology a modelling
approach was required to predict the acoustic output from the devices.

Xi produced a subsea structural-acoustic model to predict the sound power
level of the turbine array. The data was then compared with the ambient noise levels in the water, which had been measured by the Scottish Association for Marine Science (SAMS). The modelled operational noise could also be compared to audiograms for different species, giving a species
specific assessment of detectability, collision risk and injury.

Xi performed computational analysis on the drive train of the tidal turbine to
characterise the vibration signature of the device. This data was then used
as the excitation force in a structural acoustic model of the tidal turbine in
water to predict the sound pressure level of the device during different
operating conditions. Throughout the project Xi worked closely with marine
biologists and the planning team to present a comprehensive analysis of the
impact due to operational noise.