Offshore installation specialist Van Oord and acoustical engineering company AdBm Technologies have tested a system capable of reducing noise emissions from pile-driving of turbine foundations.
They claimed during tests at an unspecified wind farm under construction in late 2018, the AdBM Noise Mitigation System (NMS) contributed to a reduction of noise levels by 14-15dB.
It was used alongside a big bubble curtain — a system in which bubbles are produced to create a barrier — and was largely unaffected by waves or currents, they stated.
The NMS can help reduce disturbance for marine mammals near offshore wind farms during construction.
The NMS consists of plastic acoustic resonators, tuned to certain frequencies to capture and mitigate noise, held together by a steel frame.
It can be rolled up and down like window blinds to cover the foundation, Van Oord explained.
Specific frequencies — for example, those known to be the most harmful to local marine mammals or those that produce the most noise — can be targeted.
It is designed for use from Van Oord’s offshore installation vessel, Aeolus, and can be operational at water depths of up to 45 metres.