Instrumentation for Monitoring around Marine Renewable Energy Devices 1 Introduction As marine renewable energy has developed, a set of consistent challenges has emerged following attempts to understand potential environmental effects. In general, environmental studies conducted to date have, at high cost, demonstrated that small, pilot projects are unlikely to have environmental effects. However, these studies have often not been able to provide regulatory agencies with sufficient assurances that pilot projects ought to proceed across the globe, nor that the experience from pilot projects will scale in a predictable manner for commercial installations. If environmental monitoring costs continue to scale linearly with project size, this will likely prove debilitating to the marine renewable energy industry. Advances in instrumentation have the potential to help industry and regulatory agencies understand and mitigate potential environmental effects. However, given the limited availability of financial resources to affect these advances, there is a need to prioritize and coordinate the development of instrumentation, methodologies, and, eventually, standards for their use. 1.1 Workshop Objectives There are three principle objectives to this workshop: Enhance the understanding of the state of instrumentation readiness to answer important environmental questions for marine renewable energy developments; Develop a consensus among experts on methods for applying instrumentation to meet high priority monitoring needs for marine renewable energy projects; and Provide a forum to foster new and continuing collaboration around monitoring the environmental effects of marine renewable energy. 1.2 Workshop Structure In order to advance these objectives, this workshop will not revisit questions around prioritization of environmental studies. Rather, given a set of identified priorities, attention will be focused on instrumentation needs, capabilities, gaps, and solutions. While study methodologies, including welldefined hypotheses, are essential to the successful application of instrumentation, methodologies are not a primary workshop focus. The workshop is structured to promote dialogue around measurements of either stressors (e.g., sound) or receptors (e.g., marine mammals). The results of these measurements can then be combined in various ways to assess stressor receptor interactions. The stressor and receptor studies chosen for discussion at the workshop are intended to address: (a) the direct interaction of fish, marine mammals, sea turtles, and birds with marine energy converters (including abrasion, collision, and strike); (b) changes to distribution and use of habitats by these receptors in response to marine renewable energy generation; and (c) characteristics of the sound produced by marine energy converters. Each participant will be involved in three breakout group discussions. The first will be focused on instrumentation needs associated with a specific set of environmental uncertainties:
a) Observations of marine animals (fish, marine mammals, sea turtles, and birds) in the nearfield of marine energy converters. Such studies are often intended to detect individual interactions with converters. Nearfield is defined as within a few characteristic length scales of the converter. b) Observations of marine animal distribution and pelagic habitat use. Such studies are often intended to detect shifts at the population level. c) Measurements of the sound produced by marine converters and the temporal and spatial characteristics of this sound around converters. The second breakout will be focused on instrumentation capabilities to address these needs and are broken down by instrumentation type: a) Active acoustics: including echosounders, active tags, and radar b) Passive acoustics: including hydrophones, vector sensors, and passive tags c) Optical technologies: focused on combinations of cameras, lighting, and deployment platforms Participants will then return to their first breakout groups to discuss instrumentation gaps and solutions. The workshop will conclude with a discussion among the participants to identify high priority gaps and solutions that will assist the industry, and perhaps could be pursued in a concerted manner. 2 Scope 2.1 Marine Renewable Energy Technology This workshop focuses on two classes of marine renewable energy technology: wave energy converters and tidal energy converters. A number of the outcomes will also benefit offshore wind platforms and ocean current energy converters, but these are not intended to be the focus of workshop discussions. Wave converters deployed onshore, in the nearshore, and offshore are all within the workshop scope, as are all classes of wave converters, such as point absorbers, attenuators, surge devices, overtopping devices, and oscillating water columns. Excluded from the workshop scope are onshore facilities that are not unique to marine renewable energy, such as electrical substations or pumping facilities (e.g., as used for near shore hydraulic power take off approaches). 2.2 Geographic Extent and Environments of Interest While many workshop participants are drawn from the United States, the geographic scope for discussion is global and priority will be given to discussions of universal importance, rather than those with only a national or regional importance. Discussions of monitoring will be focused on the pelagic environment and air/sea interface. 2.3 Discussion Topics The discussion topics presented in 1.2 are, clearly, not an exhaustive list of either stressors or receptors. For example, habitat, sediment transport, and invertebrates are not the focus of discussion, nor are electromagnetic fields, chemical effects, or energy removal. These are all topics worthy of discussion in other venues and are the subject of active research programs by industry and research institutions. The focus of this workshop is on those environmental topics for which cost effective, efficient, and reproducible results have been elusive, in spite of significant field and laboratory efforts to better understand them.
The workshop focus is on instrumentation (needs, capabilities, gaps, and solutions), rather than regulations or methods. However, procedures for applying or deploying instruments are within the workshop scope. This relatively narrow focus is intended to move towards new capabilities for obtaining observations that are commonly needed across marine renewable energy technologies and geography, but have been challenging for the industry to collect at acceptable cost. 3 Environmental Monitoring Needs The first set of breakout groups are structured around specific environmental monitoring needs: nearfield interactions, distribution and pelagic habitat use, and sound. The discussion of needs have a number of common uncertainties: Are the proposed instruments appropriate for measuring the stressor or receptor of concern? What level of accuracy is desirable in these measurements (spatial, temporal, and taxonomic classification)? How confident are we that a given instrument type (e.g., multibeam echosounder) can provide information at the desired level of accuracy? For cases where instrumentation cannot provide an observation at the necessary accuracy, what are the challenges, and what steps might be taken to develop instrumentation that will meet the desired accuracy? 3.1 Marine Species near Marine Renewable Energy Devices ( Nearfield ) In the case of observations of marine species near marine renewable energy devices, the questions of accuracy and challenges take on several nuances: Which species or groups of species are most difficult to monitor and/or are of particular importance when interacting with converters? How does animal behavior affect our ability to monitor the interactions and/or what level of behavioral change do we need to be able to detect? Life stages may be important to distinguish for some animal groups (e.g., marine mammals) but there are practical considerations that make detection/identification of some life stages lower priority in the near term (e.g., larval interactions). Within this breakout group the following types of observations will be discussed: Interaction (including strike, collision, and abrasion) of marine mammals and sea turtles with converters and moorings Interaction (including strike and collision) of fish with converters Interactions (including strike and collision) of diving birds with converters Interactions (including strike and collision) of birds in the air with converters The capabilities of the following instrumentation classes will be discussed in terms of advantages, disadvantages, and needs: Split beam and multi beam active acoustics Acoustical cameras
Optical cameras (still and video) Passive acoustics Human observers Discussions will not generally distinguish between tidal and wave energy converters, as the desired accuracy for studying nearfield interactions with a wave energy converter is likely to be quite similar to studying interactions with a tidal energy converter. In cases where there are wave or tidal specific considerations, these will be highlighted. 3.2 Determining the Distribution and Habitat Use of Marine Species in the Vicinity of Marine Renewable Energy Devices ( Distribution and Use ) In the case of observations of the distribution of marine species and their use of areas proximate to converters, the questions of accuracy and challenges take on several nuances: For what species or groups of species must we be able to measure distribution and pelagic habitat use in high energy areas, in order to support decisions about siting and permitting needs for marine energy converters? To what extent must we be able to determine the normal behavior of animals in high energy areas (so we can tell if the presence of the marine energy converters changes that behavior)? Similarly to the near field, life stages may be important to distinguish for some animal groups but there are practical considerations that make detection/identification of some life stages lower priority in the near term, such as larval transport. Within this breakout group, observations of the following receptors will be separately discussed: marine mammals, fish, birds, and sea turtles. In each case, instrumentation suitability will be considered for four platforms: aerial, marine vessel, autonomous underwater vehicles, and fixed. The capabilities of the following instrumentation classes to meeting these receptor platform combinations will be discussed in terms of advantages, disadvantages, and needs: Split beam and multi beam active acoustics Acoustical cameras Optical cameras (still and video) Passive acoustics Human observers Tags Trawls Only practically relevant combinations will be discussed. For example, trawls to assess bird distribution and use will, obviously, not be considered. For the same reasons as for nearfield discussions, a distinction will not be generally made between distribution and use studies of tidal and wave energy converters. In cases where there are wave or tidal specific considerations, these will be highlighted. 3.3 Sound Produced by Marine Renewable Energy Devices ( Sound ) The objective of this discussion will be to establish approaches to developing three dimensional, timeand frequency dependent spatial maps of acoustic pressure and particle velocity around individual converters and converter arrays. The discussion will include several aspects of sound measurement,
treating tidal and wave converters separately due to the differences in sound production and ambient environments: Measurements of acoustic pressure, distinguishing converter sound from ambient noise Measurements of acoustic particle velocity, distinguishing converter sound from ambient noise Directivity of sound produced by converters Temporal variability in converter sound and ambient noise at a point in space Spatial variability in converter sound and ambient noise at an instant in time For wave and tidal energy converters, the available tools to obtain these measurements will be discussed, challenges identified, and development needs established. 4 Instrumentation Capabilities The second set of breakout groups are focused on particular types of instrumentation: active acoustics, passive acoustics, and optical technologies. For the purposes of these discussions, the focus will be on identifying the challenges for these instruments to: Measuring the animal group or stressor of interest Meet desired accuracies Be deployed across a range of seasonal, biological, or atmospheric conditions (e.g., clouds and fog seasonally interfering with optical monitoring; highly turbid water due to runoff or phytoplankton blooms) Survive in marine energy environments for extended periods of time Be permitted for use in areas with sensitive species (e.g., active acoustics in areas with ESAlisted marine mammals). Once these have been addressed, each group will discuss what research and development might help to improve the suitability of these instruments for monitoring around marine renewable energy devices. 4.1 Active Acoustics Discussions around active acoustics will focus on their suitability to meet the established needs for observing nearfield interactions and distribution. The following instrumentation classes will be discussed: Split beam echosounders Multi beam echosounders: single frequency, two dimensional imaging, three dimensional scanning, broadband Tags: fish Radar: shore and vessel based In general, no specific distinction will be made between the use of these instruments in tidal or wave energy contexts. Considerations specific to observations of birds, sea turtles, fish, and marine mammals will be identified over the course of discussion. 4.2 Passive Acoustics Discussions around passive acoustics will focus on their suitability to meet the established needs for observing distributions of marine species (primarily, marine mammals) and measuring sound produced
by converters. Tidal and wave energy converters will be discussed separately. Both hydrophones and vector sensors will be discussed and consideration given to their configuration (moored, animal borne, drifting) and connectivity (cabled, autonomous). Research and development discussions will begin with a consideration of approaches to mitigate flow noise in wave and tidal environments. 4.3 Optical Discussions around optical technologies will focus on suitability to meet the established needs for observing nearfield interactions and distribution. Optical measurements made in the water will be considered separately from those made in the air, but no specific distinction will be made between the use of optical technologies in wave or energy contexts. Optical technologies will be evaluated based on how they are deployed: vessel based (ship, ROV, AUV), aerial, animal borne, or fixed platform (shoreline, pile). Discussions will distinguish between the type of image obtained (video, still, stereo) and artificial lighting required (full spectrum, strobe, infrared). Considerations specific to observations of birds, sea turtles, fish, and marine mammals will be identified over the course of discussion. 5 Instrumentation Gaps and Solutions Following the instrumentation focused breakouts, the monitoring groups will reconvene to identify the highest priority monitoring gaps in each category, building on the work from the first breakout groups (on environmental monitoring needs), as modified from information from the second breakout groups (on instrument capabilities and configurations). Once the highest priorities gaps are identified, the discussion will turn to solutions to fill the gaps, including the application of existing instruments or groups of instruments in new and different ways, and development of new instruments or instrument packages. 6 Workshop Products The workshop discussions will be described in a summary report. All participants will have the opportunity to review and comment on the report prior to distribution.