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Scoping study: Review of current knowledge of underwater noise emissions from wave and tidal stream energy devices

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This report describes a scoping study commissioned by The Crown Estate with the aim of reviewing the current knowledge of underwater noise emissions from wave and tidal stream energy devices. This consisted of a review of existing data assembled from the public domain, as well as from commercial measurements (often commissioned by developers); a review of measurement methodologies; and a discussion of knowledge gaps and recommendations for a consistent approach. Designs of wave and tidal stream devices currently under development have a range of associated noise spectra, and this study was aimed at reviewing the existing noise data, drawing conclusions about its use in assessing the impact on marine receptors, and making recommendations for future work. As such, whilst drawing broad conclusions about the likely potential impact, the study focused on acoustics rather than biological questions related to impacts on specific species. A total of 29 relevant studies were identified worldwide, 17 of which made statements of absolute levels of radiated noise in either the operational or construction phase of development (or both). Because of the commercial nature of some of these data, it has not been possible to cite all of these results explicitly in this review. However, even where the data has some commercial sensitivity, it has been possible in most cases to describe the findings and acknowledge the existence of the work. This means that the contents of such commercial reports may be used to inform the generic conclusions of this review even though the specific noise data are not revealed here. With regard to the available data from the UK, the Pentland Firth and Orkney Waters (PFOW) developers were approached for information for this review. In addition, both Marine Scotland and Scottish Natural Heritage have supplied information. As part of the study, the authors also consulted extensively with staff of the European Marine Energy Centre (EMEC), where a number of the noise data sets described here originate. The authors are also grateful for invaluable discussions with Dr Ben Wilson of Scottish Association for Marine Science (SAMS). A number of reports describing absolute measurements were available from non-UK sources, and these were also incorporated into the review. http://www.thecrownestate.co.uk/media/151996/pfow-review-current-knowledge-underwater-noise-emissions-wave-and-tidal-stream-energy-devices.pdf
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... Much of regulatory and research interest has been concerned about noise sources that are more pervasive (e.g., vessel traffic) and/or of higher amplitudes (e.g., seismic surveys), and these concerns have been extended to MRE devices (wave energy converters [WECs] and tidal, river, and ocean current turbines). Consequently, MRE device noise or its potential impacts have been the focus of multiple studies (e.g., Robinson and Lepper 2013). ...
... The first systematic review (Robinson and Lepper 2013) reported uncertainties (e.g., uncertainty in MRE device noise characteristics, marine animal response to this noise) similar to those of a contemporary report about the environmental effects of MRE (Copping et al. 2013). ...
... Even given these uncertainties, Robinson and Lepper (2013) concluded that MRE devices were unlikely to cause acoustic injury to marine animals (even during construction) and unlikely to cause behavioral effects at long distances. A second systematic review (Thomsen et al. 2015) concluded that operational MRE device noise was not of concern. ...
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Technical Report
In A.E. Copping and L.G. Hemery (Eds.), OES-Environmental 2020 State of the Science Report: Environmental Effects of Marine Renewable Energy Development Around the World.
... It should be noted that the SL is typically estimated based on far field measurements taken at ranges much greater than 1 m from the source, and then back projected to estimate the level one would expect 1 m from the idealised monopole source. There are limitations to using this method of calculating SL (see Robinson and Lepper, 2013) but it does represent the most widely accepted method of characterising the acoustic output of a source. It should be noted that the SL does not represent the sound pressure level experienced by the fish, which will typically be at some unknown range from the source. ...
Thesis
The effects of noise on aquatic life is a topic of growing international concern. Underwater noise can impact both the physiology and behaviour of fish species on a wide-ranging scale, from minor changes and adaptations to major injury and death. Future mitigation of anthropogenic noise in the ocean is dependent on greater awareness of the effects of noise, the amount of risk, and degree of harm, likely to affect fish populations. Currently, there is a lack of incentive for mitigation measures to be put in place. Knowledge and evidence of the impacts of anthropogenic noise on fish is rapidly increasing (Figure 1.2) but with over 32,000 species of fish of differing conservation and commercial importance, it is extremely difficult to decide where to focus research for maximum benefit (Hawkins et al., 2015). Predictions and assumptions about potential impacts lack accuracy as variations in experimental equipment and techniques, lack of agreed standards, different algorithms for analysis, ambiguous and interchangeable terminology, and different quantities, units and metrics, all lead to incongruities (ISVR Consulting, 2004; Barlow et al., 2014; Rogers et al., 2016). Often it is not possible to compare studies or make generalisations (OSPAR, 2009; Wilcock et al., 2014). Here the aim is to aid the mitigation process by directing research priorities toward the most vulnerable fish species, and developing models and tools that allow for informed and cost-effective mitigation methods in a bid to reduce the effects of anthropogenic noise from marine traffic.
... The highest correlation between the underwater noise levels (L eq,63Hz and L eq,125Hz ) and the ship densities was up to 0.13 and 0.18, respectively (Tables 2 and 3), which could be explained by reduced sound wave propagation in the shallow sea [10,[17][18][19]. Low frequency sound waves below the cutoff frequency do not propagate, because the sound propagates into the sea bed [20,21]. The correlation between underwater noise and the cleaning of the sea floor was negligible (Tables 2 and 3), which was expected, because cleaning was performed with an excavator from the mainland. ...
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Article
Anthropogenic underwater noise pollution of seas and oceans caused by shipping can have negative effects on marine animals. The aim of this study was to evaluate quantitatively how much the underwater noise levels in the Slovenian Sea were influenced by anthropogenic pressures and meteorological parameters in the period from 2015 until 2018. For this purpose, correlation method and least squares multiple linear regression analysis were used. The results of this study show that the correlation of underwater noise levels with the dredging activity is significant but low, while correlation with the ship densities is insignificant, which could be due to reduced sound wave propagation in the shallow sea levels. Correlation of the underwater noise levels with the wind speed was significant but low to medium, which could be explained by the breaking waves generated by the wind that produced sound.
... Installation of devices is varied due to the diversity of device types. Pile driving is one of the nosiest methods but pile drilling, used to install piles and anchor sockets, is more relevant for MRE installations given bedrock and sediment types (Robinson and Lepper, 2013). Surveys of installation noise usually include both vessel and drilling noise (e.g., Aquatera, 2011). ...
Chapter
Understanding the complexity of environmental impacts of tidal and wave energy converters (TECs, WECs) still presents a major challenge to the expansion of the marine renewable energy (MRE) industry, particularly for new developments. Using the stressor-receptor framework, we broadly introduce the main environmental effects and potential impacts that are considered for TEC and WEC developments. We first provide an overview of the legislation that governs the need to consider the environmental impacts, and the diverse approaches taken to assess them. We then outline potential effects of relevance to the abiotic and biotic environment in the vicinity of TECs and WECs. These include receptor responses to changes in hydrodynamics and sediments, habitat modification, animal collision risk with dynamic parts of devices, and energy emissions including receptor responses to noise and electromagnetic fields associated with installations. We provide an overview of how changes may directly and indirectly influence components of the ecosystem (e.g., habitats, species, processes). In doing so, we highlight the tools presently in use to monitor or research these effects, identify knowledge gaps, as well as future research needs and strategies. A better understanding of the effects of diverse installations will ultimately support the expansion of the MRE industry. Furthermore, this knowledge will facilitate assessments of cumulative effects and inform marine spatial planning, supporting the implementation and management of sustainable developments in our ocean.
... Acoustic propagation in shallow water environments was reported to be complex because of interference due to seafloor and sea surface sound reflections and sound transmission losses [47,48]. Shallow water channels do not allow propagation of low-frequency signals due to the wave-guide effect; this implies that there would be a lower cut-off frequency below which sound waves would not propagate, since the sound propagates into the sea bed [49,50]. This phenomenon leads to the less significant contribution of shipping to underwater noise. ...
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Article
Continuous underwater noise has been monitored in the Slovenian sea near the lighthouse foundation at Debeli Rtič since February 2015, according to the EU Marine Strategy Framework Directive (MSFD). Anthropogenic noise sources (e.g. seawater densities, dredging activities and cleaning of the seafloor) and meteorological noise sources (e.g. wind speed and precipitation) were analysed in relation to the measured underwater noise levels using several graphical and statistical methods. The results of this study showed that average equivalent continuous underwater noise levels were, by 11 dB (Leq,63 Hz) and 5 dB (Leq,125 Hz), higher in the intervals when dredging activities took place than in the intervals when these activities were absent. Variation in underwater noise levels was partly related to the variation of the ship densities, which could be explained by the relatively small acoustic propagation in the shallow seawater. Precipitation level did not indicate any significant association with the variations in continuous underwater noise levels, though some larger deviations in the wind speed were found to be associated with the larger fluctuations in continuous underwater noise levels.
... The only system that has been described in detail in the peer-reviewed literature is the 2.2 MW "Arcouest" tidal current turbine (OpenHydro; Lossent et al., 2018). Information on other systems, such as the SeaGen (MCT), OpenHydro, SCHOTTEL SIT, or the Hammerfest (Andritz Hydro) turbines, resides in the grey literature such as project reports, conference proceedings, environmental impact assessments, and other non-peer reviewed documents (Robinson and Lepper, 2013;Schmitt et al., 2015;Thomsen et al., 2015). ...
Article
The underwater sound emitted during the operation of the Atlantis AR1500 turbine, a 1.5 MW three bladed horizontal axis tidal-stream turbine, was measured in the Pentland Firth, Scotland. Most sound was concentrated in the lower frequencies, ranging from 50 to 1000 Hz. Within 20 m of the turbine, third-octave band sound pressure levels were elevated by up to 40 dB relative to ambient conditions. In comparison, ambient noise at these frequencies fluctuated by about 5–10 dB between different tidal states. At the maximum recording distance of 2300 m from the turbine, median sound pressure levels when the turbine was operational were still over 5 dB higher than ambient noise levels alone. A higher frequency, tonal signal was observed at 20 000 Hz. This signal component appears at a constant level whenever the turbine is operational and did not change with turbine rotation rate. It is most likely produced by the turbine's generator. This study highlights the importance of empirical measurements of turbine underwater sound. It illustrates the utility and challenges of using drifting hydrophone systems to spatially map operational turbine signal levels with reduced flow noise artefacts when recording in high flow environments.
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A guide to recommendations for limiting the impact of anthropogenic noise emissions on marine fauna, written under the patronage of the French Ministry of Ecological Transition, this work aims to (1) provide an overview of the acoustic emissions generated by industrial activities at sea and the knowledge related to these emissions; (2) to summarise the state of knowledge on the impacts of noise on marine fauna (from invertebrates to marine mammals) and to identify the research axis to be developed; (3) to list the existing measures to avoid or reduce impacts and their degree of maturity; (4) to propose summary sheets for each activity, cross-referencing the various information mentioned in the previous points. These different points are largely illustrated and summarised in the form of summary tables. This guide is intended for government departments, marine area managers, NGOs, consultancy firms and any other structure requiring information on noise and marine fauna interactions. An introduction to the basics of underwater acoustics is also provided for non-specialists.
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Book
Guide de préconisations pour limiter l'impact des émissions acoustiques d'origine anthropique sur la faune marine, rédigé sous l'égide du Ministère français de la Transition Ecologique, ce rapport a pour objectif (1) de faire un état des lieux des émissions acoustiques générées par les activités industrielles en mer et des connaissances liées à ces émissions ; (2) de résumer l'état des connaissances sur les impacts du bruit sur la faune marine (des invertébrés aux mammifères marins) et d'identifier les axes à développer ; (3) de lister les mesures existantes pour éviter ou réduire les impacts et leurs degrés de maturité ; (4) de proposer des fiches synthétiques par activités recoupant les différentes informations mentionnées dans les points précédents. Ces différents points sont largement illustrés et résumés sous forme de tableaux récapitulatifs. Ce guide s'adresse aux services de l'Etat, gestionnaire d'aire marine, ONG, bureaux d'études ou tout autre structure ayant besoin d'informations sur les interactions bruit et faune marine. Une introduction aux notions élémentaires d'acoustique sous marine est également proposée pour les non spécialistes. Ce guide est disponible en français uniquement pour le moment, une version anglaise est en cours de rédaction.
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Underwater acoustic recordings of six Floating Production Storage and Offloading (FPSO) vessels moored off Western Australia are presented. Monopole source spectra were computed for use in environmental impact assessments of underwater noise. Given that operations on the FPSOs varied over the period of recording, and were sometimes unknown, the authors present a statistical approach to noise level estimation. No significant or consistent aspect dependence was found for the six FPSOs. Noise levels did not scale with FPSO size or power. The 5th, 50th (median), and 95th percentile source levels (broadband, 20 to 2500 Hz) were 188, 181, and 173 dB re 1 μPa @ 1 m, respectively.
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To meet the growing demand for carbon-free energy sources, the European Union (EU) has ambitious plans to increase its capacity for generation of offshore wind power. The United Kingdom and The Netherlands, for example, plan to increase their offshore power-generating capacity to 33 and 6 GW, respectively, by the year 2020. Assuming that this power is generated entirely by wind and that a single wind turbine can generate up to 10 MW, at least 3,900 offshore turbines would be required by these two states alone to achieve this goal. A popular turbine construction method known as “pile driving” involves the use of hammering a steel cylinder (a “monopile”) into the seabed. A concern has arisen for the possible effect on mammals (Southall et al. 2007) and fish (Popper and Hastings 2009) of the sound produced by the succession of hammer impacts required to sink the pile to its required depth (tens of meters).
Article
The acoustic radiation from a pile being driven into the sediment by a sequence of hammer strikes is studied with a linear, axisymmetric, structural acoustic frequency domain finite element model. Each hammer strike results in an impulsive sound that is emitted from the pile and then propagated in the shallow water waveguide. Measurements from accelerometers mounted on the head of a test pile and from hydrophones deployed in the water are used to validate the model results. Transfer functions between the force input at the top of the anvil and field quantities, such as acceleration components in the structure or pressure in the fluid, are computed with the model. These transfer functions are validated using accelerometer or hydrophone measurements to infer the structural forcing. A modeled hammer forcing pulse is used in the successive step to produce quantitative predictions of sound exposure at the hydrophones. The comparison between the model and the measurements shows that, although several simplifying assumptions were made, useful predictions of noise levels based on linear structural acoustic models are possible. In the final part of the paper, the model is used to characterize the pile as an acoustic radiator by analyzing the flow of acoustic energy.
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This document is supplied in confidence to the Scottish Executive in accordance with Contract No. 97262. The document consists of proprietary information, the property of QinetiQ Ltd, and is supplied to the Scottish Executive under the terms of the above contract. Except with the prior written permission of QinetiQ, the Scottish Executive's rights of use and dissemination of the document are limited to those set out in that contract.
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