Particle motion measured at an operational wind turbine in relation to hearing sensitivity in fish

Abstract

The effect of sound pressure on the hearing of fish has been extensively investigated in laboratory studies as well as in field trials in contrast to particle motion where few studies have been carried out. To improve this dearth of knowledge, an instrument for measuring particle motion was developed and used in a field trial. The particle motion is measured using a neutrally buoyant sphere, which co-oscillates with the fluid motion. The unit was deployed in close vicinity to a wind turbine foundation at Utgrunden wind farm in the Baltic Sea. Measurements of particle motion were undertaken at different distances from the turbine as well as at varying wind speeds. Levels of particle motion were compared to audiograms for cod (Gadus morhua L.) and plaice (Pleuronectes platessa L.).

Measurement and characterisation of radiated underwater sound from a 3.6 MW monopile wind turbine

“…This has been reported by Tougaard et al (2009) for empirical data, and shown by Marmo et al (2013) using numerical modelling. Sigray and Andersson (2011) reported a change in the turbine output characteristics in relation to its operational state. They observed the largest amplitudes for a moderate wind speed at 6 ms À1 rather than at full operating wind speed, which differs from the findings of Lindell (2003) who obtained measurements at the same site, and found the highest levels to correspond with wind speed.…”

“…Some of the earlier studies, however, comprised longer term data collection, although data analysis concentrated on subsets of the measured data (e.g., Degn, 2000;Betke et al, 2004). One study focussed on particle a) Electronic mail: tanja.pangerc@npl.co.uk motion measurements from an offshore wind turbine (Sigray and Andersson, 2011).…”

“…The sound associated with wind turbine operation has, in general, been described as continuous in nature, and characterised by one or more tonal components typically at frequencies below 1000 Hz (Degn, 2000;Betke et al, 2004;Madsen et al, 2006;Wahlberg and Westerberg, 2005;Tougaard et al, 2009;Sigray and Andersson, 2011). For turbines with a staged gearbox system, the noise output has been found to vary with wind speed, and wind-driven turbine parameters, including blade revolution, and gearbox and generator rate of operation (Madsen et al, 2006;Betke et al, 2004;Sigray and Andersson, 2011).…”

“…For turbines with a staged gearbox system, the noise output has been found to vary with wind speed, and wind-driven turbine parameters, including blade revolution, and gearbox and generator rate of operation (Madsen et al, 2006;Betke et al, 2004;Sigray and Andersson, 2011). The correlation of mechanical vibrations of the turbine tower with sound pressure and particle motion measurements in the water column demonstrated by Lindell (2003), and Sigray and Andersson (2011), respectively, corroborated the view that the origin of turbine noise lie in mechanical vibrations in the nacelle, which are transmitted down to the turbine foundation, and originate from the rotation of the wind-powered components in the nacelle. This has been supported with modelling (Marmo et al, 2013).…”

“…Some of the previous studies have investigated the relationship between wind speed induced rotation of the turbine components and the radiated underwater noise characteristics during particular wind conditions (Lindell, 2003;Betke, 2004;Tougaard et al, 2009;Sigray and Andersson, 2011), but none examined the temporal variations over a full range of operational conditions. The methodology adopted for this paper allows acoustic measurement data of the sound radiated into the water to be obtained for nominally identical wind turbines, within the same wind farm, over their full range of operational states.…”