Modelling of Noise Effects of Operational Offshore Wind Turbines including noise transmission through various foundation types

Xi Engineering

This report presents modelling of the acoustic output of operational off-shore wind turbines and its dependence on the type of foundation structure used. Three foundation types are examined: jacket, monopile and gravity foundation. The acoustic output from each of these foundation types is then compared to curves representing the hearing and behavioural response of marine species likely to come into contact with off-shore wind farms in Scottish Waters. The marine species examined are minke whales, harbour porpoise, grey seals, harbour seals, bottlenose
dolphins, European eels, allis shad, sea trout and Atlantic salmon.

Vibration produced by a generic 6 MW wind turbine was modelled across the 10 Hz to 2 kHz frequency band. The generic wind turbine was placed on the three different foundation types and the variation of the sound field in the marine environment around each foundation was modelled to a distance of 40 m from the foundation.
The resulting sound fields tend to be strongly tonal with sound pressure level (SPL) peaks associated with gear meshing frequencies in the gearbox and electromagnetic interactions in the generator.