Abstract
The nature of underwater sound generated by floating offshore wind turbines (OWTs) is of increasing interest to the renewable energy industry. This chapter presents the findings from the measurements of the first operational floating OWF, HYWIND Scotland.
Two acoustic recorders were deployed for 4 months: one at a control site and one within the OWF. Continuous tonal sounds associated with the turbine operations and transient sounds originating from the moorings were identified. The characteristics of the latter and the relevant implications for impact assessment are described. A kurtosis analysis of the sounds from the moorings of the HYWIND turbines indicated that the signals were more non-impulsive than impulsive. Directional analysis of the acoustic data revealed that different types of sounds (i.e., creaks, snaps, rattles) were generated from each of the three monitored turbines despite these having the same design. The loudness of their signals also varied according to the source. These findings show the importance of collecting in-field measurements to inform impact assessment studies. Due to the variability of these signals, characteristics from mooring noise are difficult to predict in underwater noise modeling studies.