The mitigation of underwater noise by PULSE
A study on the effects of impulse elongation and its interaction with air-bubble curtains
F. Hilmer (TU Delft - Civil Engineering & Geosciences)
A. Tsouvalas – Mentor (TU Delft - Dynamics of Structures)
Gerwin Guichelaar – Graduation committee member
A. B. Farăgău – Graduation committee member (TU Delft - Dynamics of Structures)
Yaxi Peng – Graduation committee member (TU Delft - Dynamics of Structures)
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Abstract
Nations worldwide are striving to meet the climate goals set forth by the Paris Agreement and reduce greenhouse gas emissions, with offshore wind farms (OWFs) playing a crucial role. However, OWF construction generates underwater noise from impact piling, which is harmful to marine life. This study examines the effects of PULSE – a novel mitigation measure acting as a spring-damper system between the hydraulic hammer and monopile – on underwater noise and its interaction with air-bubble curtains. Using the semi-analytical SILENCE model, the complete pile-water-soil system is simulated to evaluate noise levels, with the model’s predictions compared to field data from a recent German project. Results show that PULSE effectively reduces both Sound Exposure Level (SEL) and Peak Sound Level (Lpeak) by shifting acoustic energy from higher to lower frequencies. When combined with air-bubble curtain configurations, noise reductions are greater, but the effectiveness of PULSE diminishes. Consequently, the individual performance of PULSE and air-bubble curtains cannot be linearly added to predict their combined effectiveness. In conclusion, while PULSE effectively mitigates underwater noise, its combined use with air-bubble curtains impacts overall mitigation efficiency and requires careful evaluation.