Underwater noise measurements of a 1/7<sup>th</sup> scale wave energy converter

Bassett, Christopher; Thomson, Jim; Polagye, Brian; Rhinefrank, Ken

doi:10.23919/oceans.2011.6107283

Cited by 12 publications

(8 citation statements)

References 3 publications

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“…The acoustic impacts on marine habitat resulting from the installation and operation of the OTF should be minimized and can only be assessed from comparative studies using baseline ambient noise measurements. Recordings from a 1/7 scale wave energy conversion buoy in Puget Sound indicate the largest acoustic contribution to ambient levels from this type of device occurs in frequencies below 1 kHz (Bassett et al, 2011). This study provides an initial baseline description of long-term ambient noise levels and sound sources in the 10-840 Hz frequency range that can be utilized for future comparisons with ocean testing of wave energy conversion devices at NNMREC's OTF near Newport, OR.…”

Section: Introductionmentioning

confidence: 92%

Observations of shallow water marine ambient sound: The low frequency underwater soundscape of the central Oregon coast

Haxel

Dziak

Matsumoto

2013

The Journal of the Acoustical Society of America

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A year-long experiment (March 2010 to April 2011) measuring ambient sound at a shallow water site (50 m) on the central OR coast near the Port of Newport provides important baseline information for comparisons with future measurements associated with resource development along the inner continental shelf of the Pacific Northwest. Ambient levels in frequencies affected by surf-generated noise (f < 100 Hz) characterize the site as a high-energy end member within the spectrum of shallow water coastal areas influenced by breaking waves. Dominant sound sources include locally generated ship noise (66% of total hours contain local ship noise), breaking surf, wind induced wave breaking and baleen whale vocalizations. Additionally, an increase in spectral levels for frequencies ranging from 35 to 100 Hz is attributed to noise radiated from distant commercial ship commerce. One-second root mean square (rms) sound pressure level (SPLrms) estimates calculated across the 10-840 Hz frequency band for the entire year long deployment show minimum, mean, and maximum values of 84 dB, 101 dB, and 152 dB re 1 μPa.

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Section: Introductionmentioning

confidence: 92%

Observations of shallow water marine ambient sound: The low frequency underwater soundscape of the central Oregon coast

Haxel

Dziak

Matsumoto

2013

The Journal of the Acoustical Society of America

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“…The SeaRay WEC induced increases in spectral levels consistent with the torque and shaft speeds in the fore generator [30]. These cases provide evidence that WEC engineering processes are detectable, even when data collection efforts are not specifically geared toward their detection.…”

Section: Underwater Acoustic Monitoringmentioning

confidence: 79%

Acoustic emission health monitoring of marine renewables: Illustration with a wave energy converter in Falmouth Bay (UK)

Walsh

Bashir

Thies

et al. 2015

OCEANS 2015 - Genova

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Abstract-Marine renewable energy (MRE) is an emerging technology and at present there are an increasing number of MRE prototypes and full-scale devices deployed. The future commercialization in the near future may contribute to the mitigation of carbon emissions and diversify the renewable electricity generation portfolio. Because of the high costs of marine intervention, it is important to establish reliable, remote monitoring techniques. The underwater sound around MRE devices is often monitored for environmental impact assessments. This approach can also be potentially utilized to monitor the engineering health of MRE devices. This is the objective of the project AEMORE (Acoustic Emission technology for environmental and engineering health Monitoring of Offshore Renewable Energy), jointly conducted by the Universities of Exeter and Bath, with J+S Ltd. Acoustic Emission (AE) monitoring is already used for Structural Health Monitoring (SHM) of land-based structures and devices such as wind turbines. AE allows faults and defects to be detected early in a device's lifetime, providing more time to plan and implement necessary maintenance and repair procedures to avoid catastrophic failure. This is highly desirable for MRE structures, which operate in energetic seas with tight weather access windows. This paper explores the remit for AE monitoring to SHM and maintenance planning for MRE devices and demonstrates that this novel application is principally feasible. A brief review of the state of the art of AE for land-based systems aids to illustrate how its techniques can be applied to underwater environments and MRE components. This literature review will inform a classification system that relates likely failure modes to their expected acoustic emissions. The results from previous underwater environmental studies are used to evaluate their potential for SHM of MRE structures. AE environmental data collected during the operation of the Fred Olsen Lifesaver wave energy converter at the Falmouth Bay Test site (FaBTest, SW UK) is used to demonstrate this novel application. The case study provides proof that this concept is valid for underwater SHM of marine renewable structures.

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“…The inability to distinguish WEC sound levels from background noise -and hence nonoperational and operational modes-has been noted by a number of other studies [19,45]. The 1/7 th scale SeaRay WEC was unable to estimate the source level of the device due to local shipping [46]. This could be subject to change when arrays of devices are deployed, as the noise from multiple devices in an array would combine, as discussed by Tougaard in [45].…”

Section: Discussionmentioning

confidence: 97%

“…In half of the studies of WECs, a link is drawn between the acoustics produced and converter operation (e.g. [44][45][46]). Lepper and Robinson found a number of "events" related to the acoustic emissions of the Pelamis device (rattles, bangs, clanking etc.)…”

Section: Discussionmentioning

confidence: 99%

Monitoring the condition of Marine Renewable Energy Devices through underwater Acoustic Emissions: Case study of a Wave Energy Converter in Falmouth Bay, UK

et al. 2017

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Maintaining the engineering health of Marine Renewable Energy Devices (MREDs) is one of the main limits to their economic viability, because of the requirement for costly marine interventions in challenging conditions. Acoustic Emission (AE) condition monitoring is routinely and successfully used for land-based devices, and this paper shows how it can be used underwater. We review the acoustic signatures expected from operation and likely failure modes of MREDs, providing a basis for a generic classification system. This is illustrated with a Wave Energy Converter tested at Falmouth Bay (UK), monitored for 2 years. Underwater noise levels have been measured between 10 Hz and 32 kHz throughout this time, covering operational and inactive periods. Broadband MRED contributions to ambient noise are generally negligible. Time-frequency analyses are used to detect acoustic signatures (60 Hz-5 kHz) of specific operational activities, such as the active Power Take Off, and relate them to engineering and environmental conditions. These first results demonstrate the feasibility of using underwater Acoustic Emissions to monitor the health and performance of MREDs.

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Underwater noise measurements of a 1/7^th scale wave energy converter

Cited by 12 publications

References 3 publications

Observations of shallow water marine ambient sound: The low frequency underwater soundscape of the central Oregon coast

Observations of shallow water marine ambient sound: The low frequency underwater soundscape of the central Oregon coast

Acoustic emission health monitoring of marine renewables: Illustration with a wave energy converter in Falmouth Bay (UK)

Monitoring the condition of Marine Renewable Energy Devices through underwater Acoustic Emissions: Case study of a Wave Energy Converter in Falmouth Bay, UK

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Underwater noise measurements of a 1/7th scale wave energy converter

Cited by 12 publications

References 3 publications

Observations of shallow water marine ambient sound: The low frequency underwater soundscape of the central Oregon coast

Observations of shallow water marine ambient sound: The low frequency underwater soundscape of the central Oregon coast

Acoustic emission health monitoring of marine renewables: Illustration with a wave energy converter in Falmouth Bay (UK)

Monitoring the condition of Marine Renewable Energy Devices through underwater Acoustic Emissions: Case study of a Wave Energy Converter in Falmouth Bay, UK

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Underwater noise measurements of a 1/7^th scale wave energy converter