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Contract No. DE-AC36-08GO28308

A Review of the Environmental 

Impacts for Marine and 

Hydrokinetic Projects to Inform 

Regulatory Permitting:

Summary Findings from the 

2015 Workshop on Marine and

Hydrokinetic Technologies, 

Washington, D.C.

E. Ian Baring-Gould, Corrie Christol, and

Al LiVecchi

National Renewable Energy Laboratory

Sharon Kramer

H.T. Harvey & Associates

Anna West

Kearns & West

Technical Report

NREL/TP-5000-66688

July 2016
NREL is a national laboratory of the U.S. Department of Energy

Office of Energy Efficiency & Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

This report is available at no cost from the National Renewable Energy

Laboratory (NREL) at www.nrel.gov/publications.

Contract No. DE-AC36-08GO28308

National Renewable Energy Laboratory

15013 Denver West Parkway

Golden, CO 80401

303-275-3000 • www.nrel.gov

A Review of the Environmental 

Impacts for Marine and

Hydrokinetic Projects to 

Inform Regulatory Permitting: 

Summary Findings from the 

2015 Workshop on Marine and

Hydrokinetic Technologies, 

Washington, D.C.

E. Ian Baring-Gould, Corrie Christol, and 

Al LiVecchi 

National Renewable Energy Laboratory

Sharon Kramer 

H.T. Harvey & Associates

Anna West 

Kearns & West

Prepared under Task No. WA135301

Technical Report

NREL/TP-5000-66688

July 2016
NOTICE

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Preface

Marine and hydrokinetic (MHK) power generation is an energy source with great potential to 

provide a portion of the nation’s ongoing energy needs. However, this technology is currently in 

its infancy from a deployment standpoint and introduces new challenges to regulators, from 

early-stage prototype testing through initial commercial deployments. Given the early stage of 

MHK development, many federal, state, and local regulators responsible for permitting these 

projects (as well as other stakeholders such as industry/developers, the fishing community, and 

environmental groups) are not as familiar with the technologies and their potential environmental 

impacts as they are with existing offshore structures or onshore energy. To allow appropriate 

technical development, in-water testing is currently being conducted for single devices and small 

arrays at test centers or early development sites. Eventually the technology will evolve into 

larger, commercial-scale arrays of MHK devices. The applicability of the science and technical 

information gathered at small-scale installations to larger commercial installations is uncertain, 

but technologies will evolve and environmental impacts will be better understood through single 

device and test centers/small-scale arrays experience before fully commercial, cost-competitive 

devices are available. 

To help address the knowledge and experience gap and increase the number of early MHK 

device deployments, beginning in FY14, the U.S. Department of Energy (DOE) funded efforts to 

develop and implement technology- and application-focused workshops on MHK systems. The 

workshops engaged resource managers and other decision makers at key regulatory 

organizations, providing a review of current research and facilitating discussions with leading 

national and international experts on environmental topics such as possible and observed 

physical interactions with MHK devices, environmental effects on marine ecosystems, ongoing 

and needed research, and identifying ways to apply lessons learned from other renewable energy 

industries into the regulation of MHK systems. The workshops also allowed participants to 

discuss evolving “best practice” approaches to measurement and monitoring, as well as the 

application of risk-based approaches for baseline characterization and monitoring. Workshops in 

the Pacific Northwest and Washington, D.C., were hosted in late FY14 and mid-FY15, and 

efforts to summarize the discussions and knowledge gained were finalized in FY16. This 

document summarizes the workshop held in Washington, D.C. 
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Acknowledgments

The authors wish to thank the U.S. DOE Wind and Water Power Technologies Office for 

funding the successful MHK Regulator Workshop series and this report. Thanks to Jocelyn 

Brown-Saracino, Samantha Eaves, and Hoyt Battey for their leadership, assistance in developing 

this document, and general support of this project. 

Thank you to the technical experts who made this work possible, taking time out of their busy 

professional lives to take part in the workshop and then support the development of this 

document: 

• Chris Bassett, Woods Hole Oceanographic Institute 

• Brian Polagye, University of Washington 

• Jocelyn Brown-Saracino, U.S. DOE 

• Andrew Gill, Cranfield University 

• Craig Jones, Integral Consulting 

• Jesse Roberts, Sandia National Laboratories.

Thanks to Anna West, Kearns & West, and Sharon Kramer, H. T. Harvey & Associates, for 

facilitating components of the workshop. 

The authors would also like to thank the participants and speakers who directly contributed to the 

workshop, including the following: Mary Ann Adonizio, Verdant Power; Hoyt Battey, U.S. 

DOE; Jim Beyer, Maine Department of Environmental Protection; Stephen Bowler, Federal 

Energy Regulatory Commission; Joshua Gange, National Oceanic and Atmospheric 

Administration; Nate Johnson, Ocean Renewable Power Company; Al LiVecchi, National 

Renewable Energy Laboratory; Jeff Murphy, National Oceanic and Atmospheric Administration; 

Brian Polagye, University of Washington; Casey Reeves, Bureau of Ocean Energy Management; 

Ron Smith, Verdant Power; and Ryan Sun Chee Fore, formerly of the U.S. DOE. 

Many others contributed their experiences and ideas through interviews conducted prior to the 

workshop, including Cameron Fischer, 48 North Solutions; William Staby, Resolute Marine 

Energy; Jason Bush, Oregon Wave Energy Trust; Simon Geerlofs, Pacific Northwest National 

Laboratories; Justin Klure, Pacific Energy Ventures; Rahul Shendure, Oscilla Power; Michael 

Morrow, M3 Wave; Cherise Gaffney, Stoel Rives; Julia Wood, Van Ness Feldman; and 

Alexandra DeVissier, U.S. Navy.

Lastly, we would like to thank all of the workshop participants whose thoughtful discussions 

made this report possible. 
v 

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List of Abbreviations and Acronyms

AC alternating current

CEC current energy converter 

dB decibel

DC direct current

DOE U.S. Department of Energy

EMF electromagnetic field

Hz Hertz 

IEA International Energy Agency 

kW kilowatts

mT milli Teslas

MHK marine and hydrokinetic or marine hydrokinetic 

NMREC National Marine Renewable Energy Centers

NREL National Renewable Energy Laboratory 

OES Ocean Energy Systems

ORPC Ocean Renewable Power Company 

R&D research and development

RD&D research, development, and deployment 

SNMREC Southeast National Marine Renewable Energy Center

TWh terawatt-hours 

VAC Volts, alternating current

VDC Volts, direct current 

WEC wave energy converter
vi 

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Executive Summary

Marine and hydrokinetic (MHK) technologies generate energy from predictable currents, tides, 

ocean thermal resources, and waves. With more than 50% of the American population living 

within 50 miles of the coast, a cost-effective MHK industry could provide a substantial amount 

of electricity for the nation. The U.S. Department of Energy’s (DOE’s) Water Power Program is 

committed to developing and deploying innovative, water-based energy generation technologies.

However, the nascent MHK industry faces challenges. The technology is in an early stage of 

development, and there are few devices in the water; therefore, project impacts on the 

environment are unknown. In addition, given that the MHK industry is global, those involved in 

a specific project may not be familiar with experience and insight gathered elsewhere. A “catch 

22” exists in that there are uncertainties with these new, emerging technologies, and yet it is 

necessary to have projects in the water to be able to learn about potential project effects and the 

appropriate actions to minimize, avoid, or mitigate for them. Furthermore, the scientific 

information is still evolving as early projects, baseline and site characterization efforts, 

laboratory studies, modeling efforts, and studies conducted on similar structures in the marine 

environment contribute to the existing global knowledge base. 

Only small array or one-device installations and test centers are currently proposed or being 

implemented, and these facilities may not be able to support extensive characterization and 

monitoring given their scale. If the required technology and project cost reductions can be 

achieved, however, small-scale and eventually commercial development of MHK device arrays 

would be expected. The MHK community, including regulatory agencies, is gaining experience 

and information on the potential impacts and risks with these early deployments. This is 

contributing to the fundamental understanding of the appropriate level of ongoing monitoring 

required for single devices or small arrays versus the appropriate level for full-scale commercial 

deployments. 

In 2014 and 2015, DOE initiated efforts to develop and implement technology- and applicationfocused MHK workshops to share the global experience and knowledge base on evolving MHK 

technologies, observed and not-observed impacts, monitoring and measurement methods, and 

regulatory needs. The resulting MHK Regulator Workshops engaged resource managers and 

other decision makers at key regulatory organizations, scientists, researchers, facilitators, and 

technical experts and provided an opportunity to examine the risks of single-device and smallscale deployments, explore what can be learned and observed from single devices and smallscale arrays, and consider requirements for projects at varying scales of deployment. Experts and 

stakeholders identified key remaining information gaps. Initial discussions focused on 

differentiating between monitoring required for single or small-scale deployments and MHK 

impact research that, although important, goes beyond what is feasible or should be needed to 

meet specific project regulatory requirements but is appropriate for broader research and 

development. 

Four areas of identified potential environmental impacts provided the focus for the workshop: 

• Acoustic output impacts 

• Electromagnetic field (EMF) emissions 
vii 

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• Physical interactions 

• Environmental effects of MHK energy development on the physical environment. 

Discussions also focused on the regulatory process and experience, adaptive management, 

industry drivers, and lessons that can be learned from the wind energy industry. The discussion 

was set in the context of the types of MHK technologies that are currently proposed or planned 

in the United States. All presentations and the following discussions are summarized in this 

document, and the presentations are provided in the Tethys Knowledge Base.

1

Key Findings from General Discussion

Discussions were largely framed around what we understand regarding risk level based on data 

collected to date, what knowledge gaps remain, and whether these gaps are likely to represent 

significant enough risk to require monitoring on a project-by-project basis for single- or smallscale arrays or are questions that should be addressed through broader research efforts. 

The outcome of the workshop discussions bifurcated ongoing information-gathering into two 

general categories around the deployment of single or small-scale projects, required monitoring, 

and monitoring for research purposes. 

• Monitoring appropriate to smaller-scale projects: Conduct studies, monitor, and 

collect avoid/minimize/mitigate strategies that are appropriate for smaller-scale or 

temporary projects (e.g., one to 10 devices) where some potential impacts can be detected 

and addressed. Monitoring or modeling of acoustics, physical strike potential, and 

physical environmental impacts should be conducted if the project is to be located in a 

sensitive location or there is a high probability of interaction with a species of concern. 

Monitoring and modeling should provide information to estimate the level or risk and 

inform the need for an adaptive management strategy.

• General research/studies and monitoring to improve the understanding of the 

potential impacts of larger-scale projects: Based on what is known to date, some 

environmental impacts that may occur at larger-scale projects are not likely to occur at 

single devices or smaller arrays. Strategic research could be conducted opportunistically 

around small-scale projects or in other research endeavors to augment the state of 

understanding and help clarify the level of risk for larger-scale projects.

The resulting discussion of the four areas addressed as part of the workshop is summarized in 

Table ES-1. 

It should be noted that there is potentially much to be gained from conducting research and 

obtaining data from small-scale deployments that may assist in addressing future questions 

around larger-scale deployments. However, one of the main outcomes of the discussion was the 

general consensus that the collection of this information should not be required of a small-scale 

project as it does not pertain to the actual or potential impacts of these projects. 

 

1 http://tethys.pnnl.gov. Tethys is a DOE-funded database of MHK-related, environmental documents that is hosted 

by Pacific Northwest National Laboratory.
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Table ES-1: Recommendations for Monitoring and Research from the Workshop Presentations 

and Discussions

Monitoring for Single 

Devices/Demonstration-Scale Projects

Research for SingleDevice/Demonstration-Scale or 

Commercial-Scale Projects

Operational 

Noise 

Information collected to date indicates that 

operational devices are typically less noisy than 

other anthropogenic sources. 

Monitoring is generally not warranted as 

significant acoustic impacts are unlikely and 

difficult to distinguish from background noise.

• Data collection at demonstration scales 

may be appropriate, if detectable, to 

inform modeling for larger-scale arrays.

• Research on biological and behavioral 

implications of sound and particle motion 

would be helpful.

Electromagnetic 

Fields

No significant effects to organisms have been 

observed to date. 

Monitoring is generally not warranted since 

EMFs are likely to be low intensity and 

approach background levels within a few meters 

from the source. 

• EMF emissions are relatively scalable as 

power and voltages increase but the 

responses of any receptive animals are 

not; thus research on single devices or 

small-scale arrays may not be directly 

transferable to larger-scale projects. 

• Existing energy subsea cables can be 

utilized to assess EMF levels and animal 

behavioral responses.

Physical 

Interactions 

(Strike)

No physical interactions have been observed in 

the field. Lab experiments have found that fish 

can easily detect and avoid or swim around 

turbines and have very high survival rates when 

forced to pass through turbines. 

Any required monitoring should be based on 

risk posed at the project of interest and should 

consider that strike events are likely to be rare, 

difficult to detect, and very costly to monitor.

• Research to better understand the risk of 

strike and development of predictive 

models (e.g., location in the water column 

relative to the device, avoidance and 

evasion behaviors) and identification of 

potential mitigation actions would be 

helpful.

Impacts on 

Physical 

Systems

Numerical modeling consistently predicts that 

arrays <10 devices will have minimal impact on 

wave heights, flow patterns, and sediment 

transport.

Monitoring is generally not warranted as 

impacts from a single device or small arrays will 

likely be minimal.

• Impacts of larger arrays are unknown and 

will require more research. Data from 

eventual large arrays are needed to 

validate predictive models.

For the purposes of the workshop and this table, “monitoring” was defined as activities required of the developer by 

federal, state, or local entities to assess project impacts during operations and to fulfill legal regulatory obligations.

The level of monitoring should be based on the level of assessed risk/potential project impact posed by the project 

in question and should be directed to address specific objectives. “Research” is performed to fill gaps in 

understanding and answer questions beyond those required to meet fundamental legal or regulatory mandates. 

Research is typically performed by academia or government agencies.
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The group also discussed the potential of setting thresholds or acceptable ranges of potential 

effects for certain environmental topics to help better define more uniform assessment needs 

across single-device or small-scale array projects, although the authors are not sure how viable or 

useful such a process might be. The level or range of thresholds was not discussed, and based on 

the level of uncertainty regarding the potential impacts and importance of location-specific 

information, it is unclear if generally applied ranges could be identified or be applicable. 

As explained in further detail in the following sections, workshop participants reflected on the 

type of information available from small projects; given the likelihood of actual small-scale 

project impacts compared to the insight gained for the industry and future implications for largerscale projects, workshop participants generally agreed that with the exception of site-specific 

concerns or the potential impacts on species of concern known to frequent areas considered for 

development, the remaining questions resulting from the deployment of small-scale projects are 

more appropriately research focused. This suggests that one should consider the nature and scale 

of a project and what is appropriate if there is little direct value relating to the project of concern 

from active measurement/monitoring programs. In locations where measurement or monitoring 

needs to take place, adaptive management should be employed so that measurement efforts better 

match the need and potential impact. 

The group discussed the utility of an umbrella collaborative effort or organization such as Ocean 

Energy Systems (OES) Annex IV to serve as a central clearinghouse for the MHK industry to 

address research and monitoring needs globally. The collaboration among agencies, scientists, 

industry, environmental groups, and others can set the stage to address potential effects for MHK 

projects by researching technology innovations, providing science to support policy and 

regulatory decision-making, and enabling an information exchange to build shared knowledge 

and decrease uncertainties and perceived or real risks. 

Findings of Technical Discussions

Experts provided technical presentations in the four primary areas of acoustic output, EMF

emissions, physical interactions between aquatic animals and devices, and how the devices may 

impact the physical environment. 

Acoustic Output Impacts

The following provides an overview of the key findings on acoustic output impacts with a focus 

on small-scale MHK projects: 

• Small-scale projects are unlikely to result in physiological damage to most species since 

decibel (dB) levels are lower than those that can cause harm.

• Small-scale projects may produce sound at levels that result in behavioral impacts (i.e., 

species may avoid the device based on sounds they hear), but researchers to date have not 

gathered sufficient information to make a determination.

• For small-scale projects, it is difficult to differentiate the project-emitted acoustics from 

ambient noise in the area; therefore, required monitoring of acoustic output impacts may 

not be appropriate, especially where anthropogenic or natural background sound is likely. 
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• The biological implications of sound are highly uncertain and are driven by taxonomic 

differences; with biological relevance for certain groups being better understood than 

others. Potential biological response and behavioral context for sound emissions are

unknown and will depend greatly on the expected receptor taxonomy. 

• It is worth noting that it is unknown how the acoustic output and propagation will scale to 

larger arrays, which was one of the research-level questions identified during the 

discussions. 

Electromagnetic Field Emissions 

Research conducted to date on the EMF impacts for high-voltage subsea electrical transmission 

cables found the following: 

• Electrosensitive species can detect EMF emissions from subsea cables with likely higher 

sensitivity to direct current (DC) (0 Hertz, or Hz) than alternating current (AC) (60 Hz) 

cables because of the lower transmission frequency. Magnetosensitive species are likely 

to be able to detect EMFs from DC cables (and potentially AC cables, but to a lesser 

degree as the magnetic fields emissions are lower for AC cables).

• Behavioral responses, such as attraction to EMFs from subsea electric transmission 

cables, have been demonstrated through field and lab studies, but extrapolation to impacts 

of marine renewable energy power cables on critical behaviors of sensitive species or 

their populations would be speculative, especially for the very low power levels typically 

found in single-unit or small-array deployments.

• Since the main source of EMF emissions is the transmission cable, benthic and demersal 

species (which are closer to the source) could be exposed to higher field strengths than 

pelagic species.

• It should be noted that the difference between the existing research on EMF emissions

impacts (e.g., 33,000 volts, alternating current (VAC) and 200,000 volts, direct current 

(VDC)) and the size of the MHK deployments currently seeking U.S. permitting (480 

VAC) is orders of magnitude in difference. Although there are no identified studies on 

the impacts of EMFs, when considering low-voltage electrical cables, the impacts of 

small-scale MHK deployments on biota are considered to be inconsequential as any 

emission will be at very low levels within a very short distance (e.g., less than a couple of 

meters).

Physical Interactions

Findings based on studies to date on the potential direct and indirect physical effects of MHK 

devices (apart from issues surrounding entanglement,2 reefing,

3 and benthic habitat changes,4

which were not discussed) reveal the following: 

 

2 Marine mammals can become entangled in equipment mooring or electrical lines. 3 Reefing is the ability of the MHK device structure to attract various marine life forms and become a habitat.
xi

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• There are no observations to date of strike injury (referred to as a collision in European 

literature) or mortality in the field from tidal or current turbines, but limitations on 

monitoring are noted. 

• There is growing consensus among members of the scientific community that strike 

events for tidal turbines are likely to be rare, especially if focused on specific species of 

interest.

• Given the current limited data and limited likelihood of obtaining actual observations of 

interactions with devices in open-water settings, research to better understand avoidance 

rates coupled with predictive modeling may be the optimal course of action. 

• The limited studies using electronically tagged species (typically mammals and in some 

cases fish) demonstrate changes in use patterns to avoid turbines; however, whether this 

is the case with other untested species or whether acclimation will occur is not yet 

known. 

Environmental Effects of MHK Energy Development on the Physical Environment

Discussions around the potential indirect physical impacts of MHK devices within the ocean

system, such as sediment transport, resulted in the following general findings: 

• Modeling can be used to predict the potential changes to waves and/or water circulation 

caused by arrays of wave, tidal, and current devices in coastal regions and rivers. 

• Numerical evaluations show that small arrays (~10) of current or wave energy devices 

have minimal effect on the physical environment and effects may become undetectable as 

array size decreases. However, site-specific conditions and technology will drive the 

potential impact. 

• As array size increases, effects will likely increase and require further study.

• Devices in coastal near-shore locations may potentially be used to enhance coastal 

sediment management programs. 

• Small arrays of current energy devices will likely have localized effects on potential 

benthic habitat and the water column, with minimal effects the farther one gets from the 

device. 

• Deploying small offshore arrays (~10) of wave energy devices will have minimal nearfield effects on sediment dynamics and circulation and minimal potential for affecting 

far-field transport patterns of sediment, flow, and wave dynamics. The installation of 

single units for defined short time periods will again likely have limited, if any, long-term 

impacts.

 4 Benthic habitat is the ecological zone at the ocean floor that can be disturbed by the installation and presence of 

electrical cables, mooring lines, and other ground-mounted project equipment. 
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• Initial evaluation suggests that for small-scale arrays of MHK devices likely to have 

measureable physical impacts, adaptive management strategies that include up-front 

analysis then appropriate monitoring requirements with clear thresholds (as possible) 

leading to flexible management is likely the most appropriate path to consider. 
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Table of Contents

Executive Summary................................................................................................................................... vi

Key Findings from General Discussion ............................................................................................... vii

Findings of Technical Discussions ........................................................................................................ ix

1 Introduction........................................................................................................................................... 1

1.1 Technology Overview ................................................................................................................... 3

1.2 Environmental Effects and Processes ............................................................................................ 4

1.3 Roles and Responsibilities within the Permitting Process ............................................................ 6

2 Technical Summaries........................................................................................................................... 9

2.1 Acoustic Output Impacts ............................................................................................................. 10

2.1.1 Known Knowns .............................................................................................................. 10

2.1.2 Known Unknowns .......................................................................................................... 11

2.1.2.1 Measurement Technology, Protocols, and Standards ................................................. 11

2.1.3 Unknown Unknowns ...................................................................................................... 12

2.1.4 Summary and Paths Forward ......................................................................................... 12

2.2 Electromagnetic Field Emissions ................................................................................................ 13

2.2.1 Known Knowns .............................................................................................................. 13

2.2.1.1 Measurement Technology and Protocols .................................................................... 15

2.2.2 Known Unknowns .......................................................................................................... 15

2.2.3 Unknown Unknowns ...................................................................................................... 16

2.2.4 Summary and Paths Forward ......................................................................................... 16

2.3 Physical Interactions ................................................................................................................... 17

2.3.1 Framing Strike Risk ....................................................................................................... 18

2.3.2 Comparison with Other Sources of Blade Strike Mortality ........................................... 18

2.3.3 Known Knowns .............................................................................................................. 19

2.3.3.1 Measured and Observed Impacts for Deployed MHK Systems ................................. 19

2.3.3.1.1 Fish Strike Models ................................................................................................. 19

2.3.3.1.2 Laboratory and Field Testing of Fish Interactions ................................................. 19

2.3.4 Known Unknowns .......................................................................................................... 22

2.3.5 Unknown Unknowns ...................................................................................................... 22

2.3.6 Summary and Paths Forward ......................................................................................... 23

2.4 Environmental Effects of MHK Energy Development on Physical Environment ...................... 23

2.4.1 Known Knowns .............................................................................................................. 24

2.4.2 Known Unknowns .......................................................................................................... 25

2.4.3 Unknown Unknowns ...................................................................................................... 26

2.4.4 Summary and Paths Forward ......................................................................................... 26

3 Topical Summaries............................................................................................................................. 27

3.1 Lessons Learned from the Wind Industry ................................................................................... 27

3.2 Differences that Could Slow Industry Advancement .................................................................. 30

3.3 Information and Perspectives from Industry ............................................................................... 31

3.3.1 Project and Regulatory Perspectives.............................................................................. 31

3.3.2 Themes from Industry: Objectives ................................................................................. 31

3.3.3 Themes from Industry: General Process ........................................................................ 32

3.3.4 Themes from Industry: Risk ........................................................................................... 32

3.3.5 Themes from Industry: Data Sources ............................................................................. 32

3.3.6 Themes from Industry: Monitoring Requirements ......................................................... 33

3.3.7 Themes from Industry: Pre-Permitted Test Centers ....................................................... 33

3.4 Adaptive Management Case Studies ........................................................................................... 33
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3.4.1 Green-Versus-Green Regulatory Challenge ................................................................... 33

3.4.2 Perspectives in Adaptive Management in MHK ............................................................ 34

3.4.3 Ocean Renewable Power Company Case Study ............................................................ 34

3.4.4 Verdant Power Case Study ............................................................................................. 34

4 Research Needs and Knowledge Gaps Discussion Summary ...................................................... 36

4.1 Collaborative Interchange of Project Permitting and Research................................................... 36

4.2 Needs for Site Characterization and Environmental Baseline Assessment ................................. 39

4.3 Role of Modeling and Simulation to Address Uncertainties ....................................................... 41

5 Conclusion .......................................................................................................................................... 42

References................................................................................................................................................. 43

Appendix A: Annotated Agenda.............................................................................................................. 47

Appendix B: Additional Session Information......................................................................................... 50

Applicable Laws and Executive Orders ............................................................................................... 50

Knowledge Gaps and Research Needs: Summary Table ..................................................................... 51

IEA Annex IV and Tethys Knowledge Base ........................................................................................ 51

Appendix C: Key Contacts....................................................................................................................... 52

Report Authors ..................................................................................................................................... 52

Workshop Facilitation .......................................................................................................................... 52

U.S. Department of Energy, Wind and Water Power Technologies Office ......................................... 52

Technical and Topical Expert Contacts ................................................................................................ 52

Appendix D: Organizational Participant List.......................................................................................... 54

Appendix E: Industry Input ...................................................................................................................... 55

List of Figures

Figure 1. Primary types of wave energy devices (as cited in Chapter 9 of the Renewable Electricity 

Futures Study; illustrations not to scale) .................................................................................. 5

Figure 2. Primary types of tidal flow energy conversion devices (as cited in Chapter 9 of the Renewable 

Electricity Futures Study; illustrations not to scale) ................................................................ 5

Figure 3. The evolution of commercial wind technology ........................................................................... 29

List of Tables

Table ES-1: Recommendations for Monitoring and Research from the Workshop Presentations and 

Discussions............................................................................................................................ viii

Table 2. Recommendations for Monitoring and Research from Workshop Presentations and Discussions37
1 

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1 Introduction

The nascent marine and hydrokinetic (MHK) industry faces challenges. Although efforts are 

underway across the globe to gather and share information on MHK experience, many regulatory 

agency staff with permitting responsibilities and other stakeholders may not yet be familiar with 

all aspects of the technology and their potential for environmental effects. Furthermore, the 

scientific information on environmental impacts is still evolving as early projects, baseline 

efforts, laboratory studies, modeling efforts, and studies conducted on similar structures in the 

marine environment contribute to the existing knowledge base. 

In 2014 and 2015, DOE funded technology and application-focused workshops on ocean energy 

systems to help address the knowledge and experience gaps and increase the number of 

deployments of single and small-scale MHK arrays. The resulting MHK Regulator Workshops 

implemented by the National Renewable Energy Laboratory (NREL) engaged resource managers 

and other decision makers at key regulatory organizations, providing a review of global 

experience with deployed MHK devices. Scientists, researchers, facilitators, and technical 

experts shared science and research about the environmental effects of MHK technology. The 

workshops also provided information about the technical aspects of this technology and potential 

impacts from future projects. They provided an opportunity for regulators and stakeholders to 

examine the risks of single-device and small-scale deployments, explore what can be learned and 

observed from single devices, and consider requirements for projects at varying scales of 

deployment. Experts and stakeholders identified remaining information gaps that can inform 

future research and, if addressed, could improve regulatory approaches and address the most 

important issues given the current level of technology development. Initial discussions focused 

on possible paths forward to fill the information gaps, as well as whether the responsibility for 

meeting those needs lies with the research community, regulating agencies, or industry. 

This report provides a summary of the Washington, D.C., workshop held May 5-6, 2015, 

capturing the findings and study results shared and discussions among participants. An annotated 

workshop agenda can be found in Appendix A, and Appendix D lists the organizations 

represented at the workshop. All presentations and the following discussions are summarized in 

this document, and the full presentations are provided in the Tethys Knowledge Base.5

During the MHK Regulator Workshops, participants discussed: 

• Observed and theorized impacts from MHK devices 

• Evolving “best practices” for measurement and monitoring of key potential impacts 

• Effective implementation of adaptive management practices and other “risk-based” 

approaches as part of the regulatory process for new MHK installations.

 

5 http://tethys.pnnl.gov. Tethys is a DOE-funded database of MHK-related, environmental documents that is hosted 

by Pacific Northwest National Laboratory.
2 

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.

Armed with knowledge of the 

state of the science, technical 

aspects of the technologies, and 

potential impacts from future 

projects, regulators and 

stakeholders attending the 

workshops could examine the 

risks of single-device and smallscale deployments, explore what 

can be learned and observed 

from single devices, and 

consider requirements for 

projects at varying deployment 

scales. Experts and stakeholders 

identified key remaining 

information gaps and research 

needs that would better inform 

the regulatory processes.

Participants considered viable 

paths forward to fill the 

remaining information gaps and 

discussed what was possible to 

learn with projects of different 

scales.

The workshop provided a forum 

for regulators to become more 

familiar with the state of the 

science to inform their decisions 

in the MHK permitting process 

and to share their perspectives 

and experiences, providing 

opportunities for improved 

cooperation and coordination 

among organizations at the state 

and federal levels. The 

workshop focused on four areas 

of identified potential 

environmental impact:

• Acoustic output impacts 

• EMF emissions 

• Physical interactions 

• Environmental effects of MHK energy development on the physical environment. 

During the MHK Regulators Workshop, adaptive 

management and monitoring were discussed but not 

defined. An adaptive management strategy typically 

involves conducting monitoring or ongoing 

measurement of potential project impacts and setting 

thresholds or ranges within which actions to minimize, 

avoid, or mitigate the impacts should be taken. If no 

impacts are found, the need for continued monitoring 

can also be evaluated and potentially eliminated for 

the project. This report frequently refers to adaptive 

management and monitoring, but we recognize that it 

is not a panacea for addressing every environmental 

uncertainty and should be carefully considered in the 

context of permitting and decision-making for smallscale MHK projects.

Risk is a concept used frequently in the workshop but 

also not clearly defined. The concept of risk—the 

relative potential harm a project may have on a 

resource—was shared, as well as the idea of 

“proportional risk” (meaning that a relatively high risk 

of impacts might lead to higher investments in 

monitoring with an associated range of adaptive 

management measures, depending on the outcomes). 

Vice versa, a relatively low risk of potential harm would 

indicate a lower expectation on the extent of 

monitoring and expected adaptive management 

measures necessary. The concept of proportional risk 

can also inform monitoring needs in that gaining 

information to answer questions, thus understanding 

and documenting impact risks to inform decision 

making, is one of the primary objectives of monitoring.
3 

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In this document, Section 1 provides an introduction to the types of MHK technologies, the 

larger environmental issues identified in the deployment of MHK technologies, and the 

regulatory permitting process. Section 2 provides summaries of the technical presentations, and 

more general topical sessions are found in Section 3. Section 4 provides a review of the research 

needs identified by workshop participants. 

1.1 Technology Overview

Marine renewable energy is categorized as energy generated by waves, tidal currents, openocean currents, river currents, ocean thermal gradients, and salinity gradients, as defined in the 

Ocean Energy Glossary of the International Energy Agency (IEA) OES Agreement.6 In the 

United States, the generation technologies that combine hydrokinetic processes in the marine 

environment are often referred to collectively as MHK energy technologies. The primary forms 

of MHK discussed during the MHK Regulator Workshops were wave, tidal, tidal stream, and 

ocean current.

In the continental United States, the technical resource potential has been assessed at between 

438 and 657 terawatt-hours (TWh) of generation per year from wave, ocean current, and tidal 

technologies (DOE 2015). River-based current technology adds an additional 100 TWH per year 

of generation potential in the Continental United States (DOE 2015). Expanding the assessment 

to include all of the United States dramatically increases this estimate; however, much of that 

potential is in areas not presently accessible to the larger electrical grid. Regulatory and 

ecosystem constraints will further limit the near-term practical developable resource. Despite this 

potential, the capacity of MHK devices installed around the world is currently quite small (only 

tens of megawatts, excluding tidal barrage plants that have very different environmental impact 

considerations not considered in this document), and these installations are generally engineering 

prototype test devices or small several-unit demonstration wave and tidal projects. There are no 

full-scale, multiple-device commercial deployments in the United States at this time. 

Although MHK technologies have been under development since the 1970s, progress has been 

sporadic and they remain in an early stage of research and development (R&D), with primarily 

prototypes and early production models being deployed for testing or in demonstration projects. 

In addition to these pre-commercial models, many MHK concepts have been proposed or are in 

various stages of development with a variety of methods for energy conversion.7,8 At least 40 

MHK concepts are in development in the United States, demonstrating little convergence of the 

technology toward a particular configuration or energy resource and indicating that, at this point, 

no particular technology or configuration is deemed to be superior. Figures 1 and 2 show 

examples of the primary types of wave and tidal energy devices being developed. Some of these 

development efforts have undergone open-water testing while others have utilized international 

testing facilities.

 

6 IEA-OES 2007. Hydrokinetic forms of energy include any kinetic energy inherent to a moving fluid, such as a 

wave or flowing water. 7 DOE MHK Technology Database, available at 

http://en.openei.org/wiki/Marine_and_Hydrokinetic_Technology_Database

8 IEA OES Annual Report available at http://report2014.ocean-energy-systems.org/
4 

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To date, MHK testing facilities have been established primarily in Europe. The European Marine 

Energy Center on Orkney Island, United Kingdom, provides commercial testing services for precommercial wave and tidal devices. Wave and tidal testing facilities have also been developed or 

are in development in Ireland, Portugal, Denmark, France, Spain, and South Korea. Numerous 

pre-commercial devices, including full and subscale devices, are being tested. DOE designated 

three National Marine Renewable Energy Centers to perform research, development, and testing 

of MHK technologies in the United States. All three centers are engaged in MHK research and 

are in various stages of implementing test infrastructure. The Hawaii National Marine 

Renewable Energy Center,

9 Navy Wave Energy Test Site tests wave energy converter (WEC) 

devices. The testing arm of the Northwest National Marine Renewable Energy Center,

10 the 

Pacific Marine Energy Center, is testing WEC technology in off-grid applications and in the 

permitting process to provide the infrastructure to allow testing of grid-connected WECs. Florida 

Atlantic University’s Southeast National Marine Renewable Energy Center11 is focusing on 

technology development and testing for current energy converters (CECs), although a test site 

has not been developed. There are no available U.S.-based test centers for tidal energy 

converters. There is no requirement that devices must be tested at defined test centers. Several 

companies have elected to use their own testing/deployment locations in North America, 

although it is expected that permitted test centers will reduce the overall cost and time 

requirements for testing pre-commercial MHK technologies. 

Moving MHK technologies from their current level of maturity to commercially viable systems 

will require significant investment in research, development, and test deployment (RD&D), 

followed by significant investment in the deployment of commercial projects. MHK technologies 

will probably require an appropriate form of market support to initiate early deployments and 

reduce risk for early adopters, similar to the support provided for wind and solar technologies. 

The level of support must be sufficient to make these new technologies cost-competitive and 

allow a relatively low-risk development of the manufacturing and user experience base. This, in 

turn, will allow learning and manufacturing cost reduction that, with aggressive RD&D, can 

make MHK technologies competitive in future electricity markets.

1.2 Environmental Effects and Processes

Publications and other information sources about potential environmental effects of MHK 

projects are available for the United States and Europe, fueled by a need for improved 

understanding of the permitting (“consenting” in the European context) and licensing of MHK 

projects. Available information includes results of monitoring environmental effects of device 

deployments and studies of other structures in the marine environment. MHK environmental 

information is gathered, catalogued, and made available in the Tethys Knowledge Base, which 

also serves as a clearinghouse for information and metadata associated with MHK deployments 

in the member nations of the IEA’s OES Annex IV project (including the United States). 

 

9 For more information on the Hawaii National Marine Renewable Energy Center, see 

http://hinmrec.hnei.hawaii.edu/ 10 For more information on the Northwest National Marine Renewable Energy Center, see 

http://nnmrec.oregonstate.edu/

11 For more information on the Southeast National Marine Renewable Energy Center, see http://snmrec.fau.edu
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Figure 1. Primary types of wave energy devices (as cited in Chapter 9 of the Renewable Electricity 

Futures Study; illustrations not to scale)

Figure 2. Primary types of tidal flow energy conversion devices (as cited in Chapter 9 of the 

Renewable Electricity Futures Study; illustrations not to scale)
6 

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Europe leads recent data gathering and assessment efforts with the European Marine Energy 

Center and other deployments such as Marine Current Turbines’ SeaGen Tidal Energy 

Converter; U.S. deployments such as Ocean Renewable Power Company’s Cobscook Bay Tidal 

Energy Project are contributing to the expanded knowledge base as well. Ongoing efforts in the 

United States and Europe are evaluating environmental effects of these pre-commercial 

deployments, as well as studies of existing marine structures that serve as analogues or 

surrogates for MHK projects, modeling and simulations of potential effects, and laboratory 

studies. In addition, developing technologies and protocols to monitor environmental effects is 

also underway. 

Based on case studies, known environmental effects are varied but can include pinniped haulout12 and seabird roosting for devices with surface expression. Attraction of fish to structures, 

mooring lines, or disturbances to the sea floor can change the local ecosystem around MHK 

devices. Uncertainty surrounds fish, mammal, and seabird strikes (collisions) at tidal projects and 

EMF emissions effects of all MHK projects; however, laboratory and field studies and modeling 

are increasingly providing support for decision-making and improving understanding. 

Additionally, modeling can improve our understanding of the potential significance and 

likelihood of potential effects, such as collision risk, changes to the physical environment, EMF 

emissions, and acoustics. 

It is also uncertain how information learned from single and pre-commercial deployments will 

apply to commercial-scale arrays. Scaling results from small, local projects to larger arrays will 

be aided by modeling and scaling effects from individuals to populations and from habitats to 

ecosystems. Monitoring and adaptive management will play a role in addressing uncertainties 

and allow for informed decision-making; however, although adaptive management can provide 

some certainty for a range of potential outcomes, effective adaptive management plans should 

consider monitoring at levels proportional to environmental risk, complexity, ability to determine 

effects, and monitoring costs. 

1.3 Roles and Responsibilities within the Permitting Process

There are more than 22 applicable laws and executive orders relevant to permitting and licensing 

MHK projects in the United States.13 An MHK project requires a license from the Federal 

Energy Regulatory Commission in state waters within 3 nautical miles of the U.S. coastline, in 

U.S. rivers, and in federal waters (3 nautical miles out to 200 nautical miles) under the Federal 

Power Act if the project will be connected to the electrical grid. If the project is located in federal 

waters, it also requires a lease and right-of-way from the Bureau of Ocean Energy Management 

under the Energy Policy Act. Several state and federal agencies are involved in the licensing and 

lease processes, including the following:

Federal agencies: 

• National Marine Fisheries Service: Protects and recovers threatened and endangered 

species, marine mammals, and essential fish habitat under the Endangered Species Act, 

 

12 The process of pinnipeds (seals, sea lions, fur seals, etc.) temporarily leaving the water and climbing onto the 

MHK device

13 See Appendix B for the complete list.
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the Marine Mammal Protection Act, and the Magnuson-Stevens Fishery Conservation 

Management Act, respectively

• U.S. Fish and Wildlife Service: Protects and recovers threatened and endangered species 

under the Endangered Species Act and seabirds and bats under the Migratory Bird Treaty 

Act

• U.S. Army Corps of Engineers: Responsible for the use of navigable waterways under the 

Rivers and Harbors Act and protecting water quality and wetlands under the Clean Water 

Act

• U.S. Coast Guard: Responsible for siting and navigation aids in coastal waters under 33 

CFR 66, Code of Federal Regulations.

State agencies:

• State agencies can be responsible for Clean Water Act 401 certificates14 under the Clean 

Water Act. 

• State historic preservation offices protect historical and archeological resources through 

the National Historic Preservation Act and relevant state laws.

• State coastal zone management and land management agencies provide protection of 

coastal resources through the Coastal Zone Management Act and state laws (where 

relevant) while protecting species and habitats through state laws (where relevant). This 

may include specification of environmentally sensitive areas or the requirements to 

conduct environmental impact assessments. 

The major topics addressed in licensing and leasing projects include: 

• Commercial and recreational fishing

• Migratory bird species

• Protected species and associated habitats (marine mammals, birds, turtles, and fish) 

• View shed

• Department of Defense military training and operating areas

• Port access

• Navigation and safety 

• Archeological and cultural resources

 

14 A section of the Clean Water Act that addresses compliance. More information can be found at 

http://www.epa.gov/cwa-404/clean-water-act-section-401-certification
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• Historic places and sites

• Socioeconomic issues and environmental justice 

• Sensitive offshore and coastal habitats.

A panel discussion at the DOE MHK Regulator workshop revealed the following: 

• MHK projects face increased uncertainties given that the high-energy locations may also 

have high ecosystem value, such as containing essential habitat for protected species or 

commercially important species. Suggested solution(s): Identify risks early. Review and 

gather baseline information to inform monitoring and adaptive management planning. 

• A “chicken and egg” situation exists: There is a need for information to avoid or 

minimize impacts; but without projects in the water, there is no way to gather that 

information. Additionally, the likely very limited impacts of small projects may make it 

difficult to obtain statistically accurately information that can be used in assessing the 

impacts of larger projects. Suggested solution(s): As projects become large enough to 

obtain reliable data, work with developers to collect data to allow research questions to 

be addressed, relying on adaptive management to enable learning and adjusting. 

• Given the early stage of technology development and range of device types, it is 

challenging to anticipate the range of impacts. Suggested solution(s): For test centers that 

will use different devices, analyze a broad range of alternatives that include different 

device types so the full range of device types can be anticipated and evaluated. For issues 

of high risk and uncertainty, develop monitoring and adaptive management accordingly. 

• Understanding the extent of sensitive species in the project area is very important to 

understand potential impacts and then how to address them. Suggested solution(s): 

Conduct studies to understand if and how sensitive species use the project area as part of 

permitting to determine the extent of the presence of those species; then based on risks, 

consider post-installation monitoring and adaptive management.

• Identifying and analyzing impacts is a requirement. Suggested solution(s): Focus and 

scale the size of the study and monitoring requirements with the size of the project and 

the risk it might impose (proportional risk management). One approach might be to 

hypothesize the best- and worst-case scenarios; estimate the most likely impact; conduct 

real-world testing, including monitoring; and appropriately and adaptively manage 

based on early post-installation results.

• Information gathering should occur post-deployment but with solid study designs 

established during permitting, providing regulatory and industry certainty. Suggested 

solution(s): At a minimum, monitor potential high-probability and high-risk impacts.

• It benefits all to understand collective interests and needs; to prioritize potential impacts; 

and to develop studies, monitoring, and adaptive management plans that, to the extent 

possible, work for all. Suggested solution(s): Transparent, open dialogue is important 

and ultimately is more efficient; be open to different perspectives.
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2 Technical Summaries

The potential environmental impacts of MHK devices are varied, and due to the current state of 

the technology, not much is known about the current and potential long-term impacts of MHK 

deployment. 

As mentioned earlier, representatives from industry and government organizations discussed four 

key areas of high concern to regulators and local policy makers on MHK devices and projects: 

• Acoustic output impacts 

• EMF emissions 

• Physical interactions 

• Environmental effects of MHK energy development on the physical environment.

The following section provides a summary of the discussions on each of these areas. To help 

facilitate a better understanding of the environmental impacts, scientists and researchers shared 

their knowledge, ideas on which areas require further research, and how best to measure or 

obtain that knowledge. The workshop addressed the topics of research and knowledge in three 

levels to reflect our current understanding of the potential environmental impacts of this nascent 

technology: 

• “Known Known” topics in the technical presentations identified issues that the science 

community wants to continue to gather information about or issues that are understood 

well enough that no further monitoring is warranted. 

• The “Known Unknowns” section of the technical presentations identified issues for 

which the research community has the knowledge and technology to study but for which 

the impact and cost of a study are uncertain. Presenters examined areas that should be 

measured to enable a better understanding of the impacts, as well as what measurement 

technologies and protocols are currently available or in development and which 

capabilities are needed to study identified issues. Additionally, experts differentiated 

potential project impacts by exploring different technology scales, deployment levels, 

fluid flow rates, and MHK technologies. 

• Finally, presenters considered “Unknown Unknowns,” areas that have not been widely 

assessed, and whether it is necessary to further study the issue and make it known. For 

issues that should be studied further, presenters discussed when and how to address the 

issue and whether the technology exists to study it effectively. 

At the conclusion of each presentation, experts were asked to discuss their level of confidence in 

the available data for addressing the identified issues. Presenters also discussed the relevance of 

the current understanding to single- and small-array deployments of MHK technologies 

underway in the near term, how best to use the data collected from these projects in the future, 

the potential implementation of new technologies, and key remaining questions. 
10 

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2.1 Acoustic Output Impacts

The acoustic output of MHK deployment and operation on ocean ecosystems and marine species 

is one of the key potential impacts that concern regulators and stakeholders. This section 

provides an overview of current research and an assessment of the different methodologies to 

determine potential impacts to marine species and habitats. A workshop session provided a wider 

view of the following topics:

• What is known about sound from MHK devices? 

• How can we couple measurements and models to address potential acoustic impacts? 

• What tools are available to study this issue?

• What can we learn from other industries? 

• How can we best apply and then advance current knowledge? 

2.1.1 Known Knowns 

Impulsive sound pressure levels below 180 dB re 1 μPa are considered unlikely to cause 

physiological damage to most species and fall below the conservative interim threshold for Level 

A harassment15 of marine mammals (NOAA Fisheries 2016). For continuous sound, a level of 

120 dB has been identified. MHK devices produce sound, and sound levels for a few MHK 

technologies (wave, tidal, and riverine converters) have been measured. The impulsive radiated 

sound levels from the noisiest technology studied were reported to be up to 180 dB and 

dependent on the sea state (Lepper et al. 2012), although most other studies have suggested much 

lower levels of radiated sound. They consist mainly of mechanical sound (bangs, rattles16) and 

generator noise. However, other measurements for single units at the pre-commercial scale are 

typically indistinguishable from background noise at ranges greater than 100 m. Based on this 

and other information, we know that: 

• Operational devices are likely to produce measurable sound levels. 

• Sound intensity and frequency are likely to vary in time (based on the operational state 

and device characteristics).

• MHK devices are uncooperative sources in energetic environments, which make them 

relatively difficult to measure and quantify. 

Although full-frequency sound propagation and animal receptor sensitivity is a complicated 

relationship, the likely impacts of measured radiated sound from single MHK devices are small 

 

15 The highest level of acoustic harassment permitted by NOAA under the Marine Mammal Protection Act 16 Findings were reported in the following: “Acoustic Noise Measurement Methodology for the Billia Croo Wave 

Energy Test Site,” https://tethys.pnnl.gov/publications/acoustic-noise-measurement-methodology-billia-croo-waveenergy-test-site and the “Annex A: Summary of Operational Underwater Noise from a Wave Energy Converter 

System at the EMEC Wave Energy Test Site May 2011: Comparison of Pelamis System Operational and Baseline 

Noise Measurements,” https://tethys.pnnl.gov/publications/annex-summary-operational-underwater-noise-waveenergy-converter-system-emec-wave. 
11 

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and confined to limited areas near devices. Thus far, observed radiated sound levels are below 

those that are considered likely to cause physiological damage. Sound is also derived from the 

movement of the device in the ocean space, so it would not start without warning, naturally 

deterring sensitive species. These findings generally hold for the small converters studied to date 

(e.g., small-scale pre-commercial devices currently being tested by industry). Other observed 

findings are that, although study results are typically specific to the technology, local conditions, 

and species of concern, results can be cautiously used to draw general conclusions about the 

potential impacts of technology deployment. More data would be helpful, but data are often 

confounded by the presence of other anthropogenic noise sources in the project area (e.g., sound 

produced by MHK devices may not be detectable in an area with high levels of ambient noise). 

From a larger assessment perspective, the insight gained from small-scale or pre-commercial 

deployments may not be fully translatable to full sized devices or to larger arrays of devices, 

although data gathered on single units may inform modeling of larger-scale deployments. This is 

important because the impact of a single or small array of devices is being permitted currently. 

Although the industry may find value in conducting detailed assessments of single devices, the 

sound produced by a single device or small-scale array is likely not impactful.

Nothing can replace measurements to understand the radiated sound of a specific device and 

potentially help to improve modeling algorithms, but ongoing sound measurements will benefit 

the device manufacturers and their future technology refinement more than improving 

understanding of the impact of a single device or small array. Measurement strategies and 

equipment are well understood, but the availability of modeling-based strategies is still limited 

by the availability of device measurements. Models, especially those backed by measured data, 

can help us understand potential range of audibility or when measurable impacts may occur, but 

they cannot assess potential behavioral responses of nearby marine organisms to device noise. 

2.1.2 Known Unknowns

The results from any study are specific to the technology, local conditions, and species of 

concern; however, researchers can cautiously draw general conclusions about the potential 

impacts of technology. The acoustic footprint of an MHK project can be predicted with a 

framework that couples radiated sound measurements to infer an acoustic source level and then 

applies sound propagation models and the best available animal hearing thresholds to predict 

detection of the sound. Factors controlling radiated sound levels are largely unknown due to 

limited data, but the operational state (including currents or sea state), device scale, and 

technology type are likely important. Other important unknowns regarding radiated noise levels 

from different types and classes of MHK devices include the frequency distribution and 

directionality. Many of these questions, however, are likely immaterial to the permitting of 

current devices because based on the small numbers of systems studied, radiated sound levels 

from single or small-scale device arrays are limited to small areas near the devices and at 

intensities below those that are considered likely to cause physiological damage.

2.1.2.1 Measurement Technology, Protocols, and Standards

No standards exist for the measurement, analysis, and documentation of sound produced by 

wave, current, and ocean thermal converters, but development has begun (IEC TC114 PT-62600-

40). The required measurement technology exists, although improvements are being made as 

researchers better understand the challenges associated with taking quality passive acoustics 
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measurements in energetic environments. The primary challenges include the interference of 

turbulence, strong currents, or wave motion, which cause “flow-noise” that can mask MHK 

device noise (Bassett et al. 2014). In strong currents, stationary measurements may be 

contaminated whereas drifting measurements, which can reduce or eliminate flow noise, may 

enable device noise to be measured. However, even drifting measurements of WECs may be 

contaminated if the wave motion is insufficiently decoupled from the hydrophone. It is also 

pertinent to note that sound measurements currently focus on sound pressure, although a number 

of marine organisms (e.g., many fish species, crustaceans, mollusks) actually can’t detect sound 

pressure; rather, they respond to particle motion, a relatively new research question with no 

biological thresholds defined (Thomsen 2015). 

2.1.3 Unknown Unknowns

The concerns related to acoustics are well known even for the relatively new MHK technologies. 

Although more research, model development, data collection, and ongoing vigilance will be 

needed as MHK technologies increase in size and are deployed in larger arrays, the research 

community does not believe that there are additional issues that have not been considered 

regarding the environmental impacts of acoustic output of MHK power systems. 

The biological implications of sound and particle motion are highly uncertain; even though 

thresholds have been established for harassment for certain species, the biological response and 

behavioral context for sound emissions are still unknown. Identifying any direct biological 

responses to radiated noise from MHK devices continues to be difficult. 

2.1.4 Summary and Paths Forward

The following conclusions were drawn from existing research: 

• Demonstration-scale (single-device and small-scale array) projects are unlikely to have a 

significant acoustic impact since broadband dB levels that cause these effects are above 

180 dB and studies to date have only found decibel levels of 120 dB to 180 dB. 

• Small-scale projects may produce sound at levels that result in behavioral impacts (i.e., 

species may avoid or be attracted to the device based on sounds they hear), but 

researchers to date have not gathered sufficient information to make a determination. 

• Injury and mortality from MHK sound emissions are highly unlikely. Although device 

source levels are likely to exceed 120 dB re 1μPa (harassment), in many cases projects 

are deployed in naturally noisy environments where ambient background pre-project 

sound sources exceed this level. 

• The biological implications of sound are highly uncertain; even though thresholds have 

been established for harassment, the biological response and behavioral context to sound 

emissions and particle motion are not known (Committee on Characterizing Biologically 

Significant Marine Mammal Behavior et al. 2005). 

• Although potentially outside of any permitting requirements appropriate for these smallscale projects, opportunistically collected measurements of radiated sound at deployed 

small-scale projects can help inform important modeling parameters, provide valuable 
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data to help perform model validation, improve measurement techniques, and help to 

identify the risks associated with larger developments.

2.2 Electromagnetic Field Emissions 

To understand any impact of EMF emissions typically associated with marine renewable energy 

developments, it is necessary to consider the devices, the types of subsea power cables (AC and 

DC) and their characteristics, and the current state of knowledge regarding the effects of EMF

emissions from marine renewable energy developments on marine organisms. 

The main source of EMF emissions associated with MHK energy is regarded as the subsea 

cable(s), although depending on the device design, there may be localized EMF emissions 

associated with the actual device. The focus on the power transmission subsea cables arises 

because of the higher emission intensity associated with the cables (as compared to a device) and 

that some MHK developments may have multiple cables in a network between the devices 

before being transmitted to shore via higher power-rated cables.

It should be noted that the studies to date have focused on EMF emissions associated with subsea 

cable, in turn associated with deployment of large-scale offshore renewable technologies such as 

offshore wind that typically use medium-transmission voltage of 33,000 to 150,000 V (AC – 50 

Hz) and long-haul undersea DC transmission lines up to 200,000 V (DC). Typical single- or 

small-array pre-commercial MHK technologies being deployed in the United States are only 

testing very small power generation devices (up to 100 kilowatts, or kW) with voltages up to 480 

VAC; 2 orders of magnitude smaller than most of the studies that are available to assess the 

impacts of EMFs on marine species. The difference in target voltage and electrical current of 

ongoing research on the impacts of EMF emissions and the size of the MHK deployments 

currently seeking U.S. permitting is quite large, meaning that the findings discussed below 

represent impacts that are unlikely to be seen in small-scale deployments. No documented study 

of EMF levels for devices currently deployed or under permitting has been undertaken. 

2.2.1 Known Knowns 

Ability to sense and respond to EMFs is widespread across taxonomic groups, ranging from 

bacteria to whales. Since the main source of EMF emissions is the transmission cable, benthic,17

and demersal18 species, which are closer to the source, are considered to be more likely to be 

exposed to higher field strengths than pelagic species. Interest tends to be focused on: 

• Elasmobranchs (sharks, skates, and rays) 

• Agnatha (lampreys)

• Chondrosteans (sturgeon, paddlefish) 

• Crustacea (lobsters, crabs, and prawns)

• Mollusca (snails, bivalves, cephalopods) 

 

17 Species that live on or in the sea floor 18 Species that live close to the sea floor
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• Cetacea (whales and dolphins) 

• Bony fish (teleosts) 

• Marine turtles.

Consideration of potential impacts is similar across large-scale energy devices in the marine 

environment and typical subsea power networks. The impact is based on the cable material 

characteristics, the transmission voltage, and current being transmitted, which generates the 

magnetic fields. These directly emitted magnetic fields are the source of induced electric fields, 

thereby giving both magnetic and electric fields in the environment. For transmission-level 

power systems studied to date, with voltages of 30,000 VAC or above and power levels of multi 

megawatts (thousands of kilowatts), the following findings are generally accepted: 

• Electrosensitive species can detect EMFs from subsea cables with likely higher 

sensitivity to DC (0 Hz) than AC (60 Hz) cables because of the lower transmission 

frequency and higher power rating of the transmission cables (Normandeau Associates 

Inc. et al. 2011). The most highly sensitive taxa are elasmobranchs (sharks and rays) and 

agnathans (jawless fish) (Normandeau Associates Inc. et al. 2011; Gill et al. 2014). 

• Magnetosensitive species are likely to be able to detect EMFs from DC cables and 

potentially AC cables but to a lesser degree as the magnetic fields emissions are lower for 

AC cables (Westerberg and Lagenfelt 2008; Gill et al. 2014). 

• Behavioral responses, such as attraction to EMFs from subsea electric transmission 

cables, have been demonstrated through limited field and lab studies, but extrapolation to 

impacts of marine renewable energy power cables on critical behaviors of sensitive 

species or their populations would be speculative (Öhman, Sigray, and Westerberg 2007; 

Woodruff et al. 2013; Gill et al. 2014). 

• Since the source of EMFs is the cable on the sea floor, benthic and demersal species, 

which are closer to the source, are considered to be more likely to be exposed to higher 

field strengths than pelagic species (Woodruff et al. 2013; Gill et al. 2014). 

• Laboratory studies have shown that exposure to EMFs of 3 milli Teslas has documented 

impact on a number of marine species, including Atlantic halibut, rainbow trout eggs, and 

coho salmon. It should be noted that 3 milli Teslas EMF levels are much higher that what 

would be expected for the deployment of single-unit or small-array MHK systems 

(Woodruff et al. 2013). 

• Measurements taken as part of an assessment for multi-megawatt offshore wind projects 

using transmission-voltage power cables in Europe found EMF levels of up to 18 micro 

Tesla (0.018 milli Teslas, 2 orders of magnitude below the levels of EMF documented as 

being impactful) for AC systems and ~275 micro Tesla (0.275 milli Teslas, 1 order of 

magnitude below the levels of EMF documented as being impactful) for DC-based 

systems (Normandeau Associates Inc.et al. 2011). Small-scale MHK projects will operate 
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at voltage and power levels likely 3 orders of magnitude smaller than current offshore 

wind farms.

2.2.1.1 Measurement Technology and Protocols

The European Union Environmental Impacts of Noise, Vibrations and Electromagnetic 

Emissions from Marine Renewable Energy (MaRVEN) project provides the most current review 

of the state of the art for measurement technologies and protocols. This work includes: 

• Examples of measurement instruments, sensors, results, applicable standards 

• Potential for models to support or replace the use of measurement 

• Information required for measurement programs to develop valid modeled impact 

assessments

• A summary of the level of uncertainty around existing measurement and modeling 

options for the interpretation of their results.

Outputs from the MaRVEN project are not available to the public at the time of writing; a 

summary of the outputs is available (Thomsen 2015). 

2.2.2 Known Unknowns

Several aspects of known concern should be determined to enable understanding of the impacts 

of EMFs. These aspects center on dose-response relationships, particularly knowing the 

response/effect on key marine species at their most sensitive stages of life to exposure to a range 

of EMF emissions (sources and predicted intensities). 

• Knowing how EMF receptor species respond to multiple encounters with subsea cables in 

relation to movement/migratory behavior is required, such as through animal tracking 

field studies using multiple individuals. 

• Any effects/responses measured need to be considered over the range of biologically 

relevant EMFs, which may result in attraction to cables rather than avoidance. 

• The determination of impact lies in the data analysis that needs to apply analytical 

methods to assess emergent properties associated with impact at the biologically relevant 

unit of the species population. 

Additional unknowns include a large uncertainty about the actual levels and characteristics of 

EMFs emitted from the marine renewable energy development cables and the fact that cables 

vary according to different manufacturing processes and different cable characteristics and 

deployments (e.g., burial vs. rock armoring), and the power generation units/devices will differ. 

These differences create uncertainty in emitted levels that cannot be modeled owing to lack of 

baseline data. Hence, it is important to understand the sources of variability in the emitted fields 

and to develop affordable techniques for measuring EMF emissions that receptors are likely to be 

exposed to so as to validate EMF predictions within models. 
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If EMF emissions are deemed to be significant, then guidelines and standards for measuring 

EMF emissions should be developed. 

2.2.3 Unknown Unknowns

Given that the expanded use of undersea transmission cables and the deployment of marinebased power generation technologies are recent occurrences, there are still many unknowns 

about the potential impact of EMF emissions. Three such potential unknowns include:

• Possible differences in the potential behavioral response of EMF-receptive species within 

a cable “mesh” with cables oriented in different directions and relatively close together, 

typical of a collection system for an array of devices, compared to single long linear 

shore landing cables

• Potential impacts on the life stages of migratory animals due to the potential cumulative 

impact of encountering repeated EMF sources along a migratory path given that multiple 

projects and thus multiple shore landing cables from larger-scale marine renewable 

energy may eventually be implemented 

• Potential longer-term EMF impacts on early life stages as many early life stages are 

relatively immobile and therefore may be exposed for long periods during development. 

2.2.4 Summary and Paths Forward

Most of the understanding relating to EMF impacts is for medium-voltage transmission and 

above, typically in the range of 33,000 to 150,000 (VAC – 50 Hz), and relatively large power 

ratings, typically more than 50,000 kW. Current small-scale deployment for MHK technologies 

is at relatively low voltages (1,000 VAC or below) and low power ratings (less than 100 kW). 

Although there is value in understanding the impacts of EMFs for larger-scale deployments, the 

assessment of EMFs for small, single, or small-array projects is not likely warranted. 

When considering larger power systems, there is still a low level of confidence in the data for 

assessing whether there is an issue/concern. Additional work should build on the extensive 

deployment of offshore energy cables in Europe and the subsea cable industry in general to 

assess and share data on EMFs, cables, and impact studies, much of this relating to the offshore 

wind sector and the related subsea cable, network, and grid-connection sector. 

Workshop participants reviewed the potential impacts of EMF emissions from subsea AC and 

DC cables and the current state of knowledge regarding the effects of EMFs from subsea cables 

on marine organisms. It should be noted that the studies to date have focused on the EMFs for 

transmission-level power cables associated with the deployment of large-scale offshore 

renewable wind energy technologies from multiple high-power devices (1 to 5 MW) that 

typically use medium-transmission voltage and long-haul undersea DC transmission lines up to 

300,000 V (DC). Small-scale MHK technologies currently seeking permitting for deployment

test low-power-generation devices (up to 100 kW) with voltages up to 480 VAC; 2 orders of 

magnitude smaller. Although there are no identified studies on the impacts of EMFs on 

receptors, over the longer term a considerable improvement in understanding of EMFs from 

MHK devices will be needed to aid the permitting process for large-scale deployments. At 
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present, the impacts of small-scale MHK deployments on biota are considered to be of low 

overall biological significance because any EMF emitted that is detectable is likely to be low 

intensity and approach background levels within a very short distance (e.g., less than a few 

meters) from the source.

2.3 Physical Interactions

The direct and indirect physical interactions of marine species with MHK devices and systems, 

moorings, and electrical interconnections are another potential environmental concern. While 

potential physical interactions between MHK devices and marine organisms have been identified 

through broader consideration, the workshop focused on blade strike. The workshop session did 

not focus on other potential interactions, which are listed and described below: 

• Entanglement in moorings and electrical interconnections. Entanglement from MHK 

device moorings and other cables is generally considered to be a relatively low risk due 

to cable thickness and mooring line tension. 

• Changes to movement/habitat use patterns. Substantial changes to movement patterns 

are unlikely to result from small-scale projects; as such, this hasn’t been an area of 

extensive research to date. Studies examining changes in movement patterns have 

revealed only localized change in movement patterns around devices, as opposed to 

MHK devices serving as barriers to movement on a broader scale. This question will 

need to be addressed as project sizes increase.

• Reefing/fish aggregating devices. While MHK devices may act as fish aggregating 

devices and artificial reefs, these effects are likely to be very location dependent and 

relatively minor with small-scale projects. For larger-scale projects, reefing effects may 

have positive, negative, or neutral effects on local populations. Additionally, this effect is 

likely to be similar to that of other ocean structures, so existing data may be used to 

assess likely MHK project risk. 

• Benthic habitat changes. While changes to benthic habitat around anchors and/or 

benthic expressions of devices are likely with both positive and negative impacts 

possible, such changes are likely to be localized for small-scale projects. Additionally, 

this effect is one common among all ocean equipment with a benthic expression; existing 

data may be used to assess likely MHK project risk. 

• Blade strike. Additional attention and research have been devoted to assessing the 

potential risk of blade strike from tidal, ocean, or in-river devices. While varied in design, 

most CECs and tidal turbines have moving blades that are used to capture kinetic energy 

from moving water. This design structure, informed in part by historical issues regarding 

fish injury and mortality from hydropower turbines, have led to concerns regarding strike 

injury and mortality from tidal turbines. 

Risk of blade strike from tidal turbines to date has been informed by modeling, laboratory 

studies, and field studies. The IEA OES Annex IV Final Report19 provides an overview of 

 

19 http://www1.eere.energy.gov/water/pdfs/annex_iv_report.pdf
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research conducted to date, and much of the material presented at the workshop was included in 

or informed by this document. 

2.3.1 Framing Strike Risk 

Risk is generally considered to be a function of the probability of an event occurring and the 

consequence of the event, should it occur. To understand the ultimate effect of such impacts, risk 

to populations, rather than individuals, will need to be analyzed. Population risk is dependent on 

the vulnerability of a population. Consequently, when considering the potential risk due to blade 

strike, risk to individuals should then be placed within a broader population framework. 

Blade strike risk to individuals depends on a number of variables, including: 

• The individual probability of being struck (probability of encounter), which will depend 

on key considerations such as: 

o Where is the device in the water column relative to a species’ swimming patterns, 

presence, and abundance? 

o Do organisms respond to the device in such a way as to increase or decrease their 

strike risk through attraction, avoidance of the turbine (macro-scale) or the rotorswept area (micro-scale), and evasion (the organisms’ ability to time their passage 

through the turbine in such a way to avoid being struck)?

• If an individual strike event occurs, what are the consequences of that impact (impact of 

encounter)? Consequences will depend on: 

o The force associated with the strike event

o The organism, the location of strike, and a number of device-specific design 

considerations. 

• Based on the probability of a strike and its direct impact, is there a resultant populationlevel effect that is of concern? 

2.3.2 Comparison with Other Sources of Blade Strike Mortality 

Since concerns regarding blade strike from MHK turbines are rooted in a history of concerns 

regarding mortality from hydropower turbines and ship propellers, a comparison of the 

mechanisms of mortality between these technologies can be informative to our understanding of 

relative strike risk. An Electric Power Research Institute report (Jacobson et al. 2012) compared 

fish mortality mechanisms between hydropower and MHK technologies and concluded: 

“Fish passing through the blade sweep of a hydrokinetic turbine experience a 

much less harsh physical environment than do fish entrained through 

conventional hydro turbines. The design and operation of conventional turbines 

results in high flow velocities, abrupt changes in flow direction, relatively high 

runner rotational and blade speeds, rapid and significant changes in pressure, 

and the need for various structures throughout the turbine passageway that can 

be impacted by fish (e.g., walls, stay vanes, wicket gates, flow straighteners). 

Most, if not all, of these conditions do not occur or are not significant factors for 
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hydrokinetic turbines. Furthermore, compared to conventional hydro turbines, 

hydrokinetic turbines typically produce relatively minor changes in shear, 

turbulence, and pressure levels from ambient conditions in the surrounding 

environment.” 

Further, the potential for device avoidance is a critical difference between the two systems. Fish 

passing through hydropower turbines are entrained in rapidly flowing water and confined within 

the draft tubes, with relatively little ability to evade blade strike. In contrast, if organisms sense 

and perceive MHK turbines as they do other objects in the aquatic environment, they have the 

potential to swim around the devices or to evade blade strike by timing their passage through 

devices. 

At times, risk of blade strike from MHK turbines has been compared to that of ship propellers. 

Since force is a function of mass multiplied by acceleration, the relative force of strike from tidal 

turbines is likely to be far less than that of ship propellers, as propellers have external energy 

source and tidal turbines move with the current. 

2.3.3 Known Knowns 

Risk of blade strike from tidal turbines to date has been informed by modeling, laboratory 

studies, and field studies (Copping et al. 2013), summarized in the findings section below. 

2.3.3.1 Measured and Observed Impacts for Deployed MHK Systems

The following summarizes known impacts of deployed MHK systems. 

2.3.3.1.1 Fish Strike Models

Numerous approaches to the modeling of direct fish strike from tidal and current MHK 

technologies have been developed, ranging from models adapted from hydropower to new 

computational fluid dynamic models. The models examine the two main issues introduced 

above: the probability of an interaction and the consequence of that interaction.

It is important to note that most of these models do not incorporate avoidance or evasion rates 

but tend to model the fate of fish that pass through turbines rather than the likelihood that any 

fish passing through an area will encounter a turbine, fail to avoid it, and fail to evade the strike. 

Thus the results of these models should be viewed in this context. 

Several models have been developed that are informed by field data for development. The 

Eulerian-Lagrangian-Agent Method (ELAM)20 model uses data informed by mobile hydroacoustic surveys at the Ocean Renewable Power Company Cobscook project and a model being 

developed by Oak Ridge National Laboratory using data from Verdant Power’s Roosevelt Island 

Tidal Energy project in New York. 

2.3.3.1.2 Laboratory and Field Testing of Fish Interactions 

Laboratory-based work has been performed to help understand the survival rate of fish based on 

flume studies, including the following: 

 

20 See U.S. Army Corp of Engineers Cognitive Ecology & Ecohydraulics Research description: 

http://el.erdc.usace.army.mil/emrrp/nfs/elam.html
20 

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• Laboratory tests indicate high survival rate (close to 100%), including avoidance (not 

entering the rotational plane) and evasion rates (successfully moving through the rotor 

plane without being struck), for multiple exposed fish species in light and dark 

conditions. 

• Multiple field tests have also been conducted for MHK technologies using rotating blades 

across multiple locations, water types, and turbine technologies for fish and marine 

mammals, including:

o A Hastings, Minnesota, project that consisted of a Hydro Green Energy Turbine 

on the tailrace of an existing hydroelectric dam on the Mississippi River 

(completed in 2009). The organisms of interest included the yellow perch (Perca 

flavescens), bluegill, catfish, smallmouth buffalo (Ictiobus bubalus), and 

bigmouth buffalo (Ictiobus niger). In this study, fish were outfitted with radiofrequency tags and balloon tags that inflated after passage through the turbine. 

The fish introduced directly upstream of the turbine and retrieved downstream 

after passage through the turbine were assessed for mortality and injury 1 hour 

and 48 hours after retrieval. The key findings were that survival was ≥99% after 

48 hours, with only one yellow perch sustaining what may have been a test 

process-induced injury out of a total sample of 396 (Normandeau Associates Inc. 

2009). 

o The Gorlov Helical Turbine Test examined naturally occurring fish in a 

subtropical tidal channel in Mozambique using a stereo-optical camera 

measurement system. Fish movements were recorded with and without the rotor 

in place for a turbine rotation up to 70 rpm. Although differing by species, fish 

movements through the test area were reduced when the rotor was present and 

increased with current speed. No fish collided with the rotor, and only a few 

passed through rotor blades (Hammar et al., Andersson and Eggertsen 2013). 

o In 2006, the European Marine Energy Centre conducted a study of the impacts of 

OpenHydro 6-m ducted tidal turbines, primarily on Pollack (Pollachius 

pollachius). Hundreds of hours of video footage using natural light have been 

collected at the face of the OpenHydro turbine. Pollack were the only species 

detected in the vicinity and only at low-tide states. Pollack abundance was 

significantly inversely associated with velocity, with no fish present at flow rates 

above 1.2 m/s in 2009 and 1.7 m/s in 2010. Collision and entrainment were not

observed (Broadhurst, Barr, and Orme 2014). 

o In Cobscook Bay, Maine, testing was conducted on an Ocean Renewable Power 

Corporation (ORPC) turbine. Single-beam hydroacoustic technology was used to 

collect pre-deployment data on the presence and vertical distribution of fishes. 

DIDSON cameras then recorded fish behavior around the turbine. Based on 3 

years of data collected, fish density was usually highest near the sea floor (below 

the depth of the turbine), although this varied with seasons. A few fish were seen 

actively avoiding the turbines, but 35% fewer fish went through turbines when 

spinning. Additionally, fewer schools passed through turbines than independent 
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fish. It is possible that larger fish avoid the turbine farther outside of the view of 

the cameras, but this could not be proven (Zydlewski 2015). 

o The Roosevelt Island Tidal Energy Project in New York’s East River considered 

the impact of six tidal turbines from Verdant Power in 2008. The project looked at 

resident and migratory fish using two acoustic cameras, downward-looking split 

beam biosonic transducer and a DIDSON camera system oriented toward a 

turbine to observe fish movement and behavior (Verdant Power LLC 2010). The 

monitoring system was deployed for three 15- to 17-hour periods. Key findings 

were that resident and migratory fish avoided the areas where turbines were 

located and tended to prefer inshore, slower-moving waters. Fish behavior was 

primarily influenced by the natural tidal currents and secondarily by the presence 

of the operating turbines. There were few fish present while turbines were 

operating, which only occurred when the flow velocity increased to greater than 

approximately 0.8 m/s, the turbine cut-in velocities. Limited observations showed 

fish passing by the rotating turbines following the hydrodynamics of the system, 

indicating that fish were able to detect and successfully swim around operating 

turbines (Tomichek 2015). 

Additionally, two studies have examined blade strike risk for marine mammals. 

• The SeaGen marine current turbine’s testing at the Strangford Lough special area of 

conservation in Ireland focused on gray and harbor seals and harbor porpoises. The 

project worked to eliminate strike risk to marine mammals by shutting down the turbine 

during daylight hours when marine mammals were sighted nearby and also after dark. 

Distances and protocols triggering shutdown were reduced over time, and the role of 

marine mammal observers was augmented and then replaced by a sonar unit. At the start 

of the project, turbines shut down on average three times per 24 hours of operation; later 

in the project, shutdown occurred less than once per 24 hours of operation. Shutdowns 

were more frequent on the ebb tide than the flood tide. Turbine shutdown procedures did 

not allow for observations of direct interactions of the animals with turbine blades, but 

seal telemetry data showed that seals transited farther away from the center of the 

narrows after SeaGen installation, suggesting avoidance of the turbine. This project 

continues operation (Sea Generation Ltd. 2016) although it is expected to be removed in 

2016 to further understand the decommissioning process of MHK devices (BBC News 

2016). 

• Sandia National Laboratories and the Pacific Northwest National Laboratory conducted 

an assessment of the strike risks to an adult killer whale by an OpenHydro Open-Center 

Turbine, tidal turbine blade.21 This study provided an estimate of the worst-case scenario 

results of a modeled blade strike on material with properties similar to killer whale tissue. 

The modeling concluded that interaction was likely to result in bruising or minor 

laceration under a worst-case scenario; however, the study did not account for aspects of 

whale behavior nor provide detailed information about the strengths of specific whale 

 

21 http://www.openhydro.com
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tissues. This analysis may not be generally applicable to encounters between other 

species of animals and other turbine designs and is still ongoing (Carlson et al. 2014). 

2.3.4 Known Unknowns 

Several major known unknowns have been identified. 

Measurement technologies:

• There are currently no commercial off-the-shelf technologies that are ideal for monitoring 

collision or evasion in the near field in low-light, high-energy environments. Of the 

current technology solutions, optical systems require natural or artificial light sources 

(artificial light may attract or repel some organisms), are at risk for biofouling and 

clouding lenses, and produce large amounts of data. Active acoustic systems result in 

clutter around the blade surface that makes collision events hard to detect, are typically 

data intensive to operate over long periods, and have limited species classification 

capabilities. Accelerometers applied to blades or devices that are capable of detecting 

strikes are still in a research stage.

• The most promising monitoring solutions likely integrate an instrumentation package. 

The University of Washington Northwest National Marine Renewable Energy Center, 

among others, is developing packages, but they are in the research phase of development 

and testing. However, such packages are likely to be expensive and data intensive and 

will likely be more appropriate for answering research-based questions, rather than 

routine project monitoring.22 

• Attempting to monitor strike events has been and will continue to be very expensive. It 

may be more appropriate for research to inform a broader understanding of risk, rather 

than aiming for continuous monitoring at projects. 

Other remaining questions: 

• What is the degree to which different species will avoid turbines in their path? The 

limited studies show that mammals, and in some cases fish, demonstrate changes in use 

patterns to avoid turbines; however, for fish these rates have varied among studies. How 

this may change over time or with different untested species in different flow regimes and 

light conditions is not yet known. 

• How do turbine arrays affect fish avoidance ability? High survival rates for fish passing 

through turbines are promising, even if avoidance rates are low. 

2.3.5 Unknown Unknowns 

No specific concerns were identified based on the experts’ experience.

 

22 For more information, see 

http://tethys.pnnl.gov/sites/default/files/publications/Instrumentation_Workshop_Final_1_2014_0.pdf
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2.3.6 Summary and Paths Forward

Workshop participants discussed what is known regarding risk of blade strikes from turbines to 

marine organisms; findings to date include the following: 

• There have been no documented observations to date of strike, injury, or mortality in the 

field from tidal turbines. There are limitations on monitoring efforts to date, so there is 

the potential of strikes that have not been documented. 

• Field data findings are supported by flume studies, which also indicate high survival rates 

following passage through MHK turbine blades (likely due to the relative slow rotation 

rates and thus strike force, as well as the ability of fish to avoid and evade strike). 

• When applying or interpreting the results of MHK strike models, users should pay close 

attention to whether models include avoidance and evasion rates. Those that don’t are 

predicting the fate of organisms that pass through turbines, rather than the probability of 

passing through. 

• There is growing agreement in the scientific community that strike events are likely to be 

rare at small or pre-commercial projects, especially if focused on species of interest.

• Rareness of strike events will make them inherently hard to observe; therefore validating 

monitoring technologies and modeling results using observed strike events will be 

difficult. 

• Different turbine types have different rotor-tip speeds and strike forces; thus 

understanding the properties of a specific turbine is important in predicting strike and the 

potential impact of that strike. Site-flow rates will also affect rotational velocity and thus 

strike force, adding an additional degree of freedom. 

• Strike monitoring has been and will continue to be very expensive, with limited expected 

avenues for improvement given the scale of the issues and technology currently in use 

and being developed. 

Given the limited likelihood of obtaining observations of interactions with devices in open water 

settings, research to better understand avoidance rates coupled with predictive modeling may be 

one viable course of action. 

2.4 Environmental Effects of MHK Energy Development on Physical 

Environment

The presence of MHK devices in the natural environment has the potential to create changes in 

local ocean ecosystems. The physical environment is considered the water body and seabed in 

which the device is located, and the potential effects would include changes in water flow, water 

quality, and sediment dynamics. Key questions for assessing this impact over the course of the 

installation include:

• How is the physical environment changed by MHK installations? 
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• Are the changes significant and cause for concern?

• Can mitigation strategies be effective in reducing or eliminating the impacts?

• Can the installations be engineered to improve conditions or address other concerns? 

This review does not examine acute impacts, including short-term disturbances around the 

installation of devices (e.g., pile driving, vessel traffic) or the more conventional and better 

understood physical impacts of the anchoring systems or power transmission trenching. 

2.4.1 Known Knowns

Limited studies have been undertaken to date to consider physical environmental effects due to 

the presence of MHK arrays in aquatic systems. The studies include numerical simulations of the 

physical effects of arrays of MHK devices, including WEC effects on waves and currents and 

subsequent seabed changes. Researchers have also analyzed the effects of CECs on the natural 

currents, sediment dynamics, and water quality in tidal and riverine systems. However, few 

devices have been deployed in multiple environments, which make results difficult to interpret 

more broadly. 

Although site-specific conditions and technology will drive the potential impact, numerical 

evaluations show that small arrays (~10) of WEC and CEC devices generally have minimal 

effect on the physical environment. Depending on the type and duration of small-scale 

installations, the impacts of these deployments are expected to be minimal. If the deployments 

are temporary to allow development testing, the impact of these devices is likely not meaningful. 

However, as array size increases, effects increase and require further study.

Findings from CEC studies have shown that small arrays of devices will likely have localized 

effects on potential benthic habitat and the water column but minimal effect far-field. The 

impacts of a single device for testing purposes are also expected to be small to negligible.

The deployment of a small offshore array (~10) of WEC devices will have minimal near-field 

effects and minimal potential for affecting far-field transport patterns. The installation of single 

units for defined short time periods will again likely have very limited, if any, long-term impacts.

Researchers have undertaken several studies and modeling efforts for WEC devices, with 

findings that include: 

• Modeling using the Simulating Waves Nearshore (SWAN)23 wave model showed that 

change of shoreline wave climate caused by the installation of a small array of WEC 

devices at probable wave energy transmission levels predicted only small changes in the 

shoreline wave climate (Jones, Magalen, and Roberts 2014). 

• The distance of a wave farm to the coast is one of the key aspects in a wave energy 

project. Modeling results show that a small array of WEC devices within 2 to 3 km of the 

 

23 For more information on SWAN, see http://swanmodel.sourceforge.net/
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coast results in beach erosion reduction of up to 20% (Abanades, Greaves, and Iglesias 

2015).

Methodologies to understand and estimate impacts around wave energy and subsequent sediment 

dynamics have not been universally accepted. Baseline observations and modeling at a proposed 

wave energy array site near Reedsport, Oregon, included beach and shoreline morphodynamics 

assessments, direct survey, and video observations of the submerged bathymetry, wave 

modeling, and in-situ and radar observations of the waves (Ozkan-Haller et al. 2009). 

Similar studies and modeling efforts have been undertaken for current energy devices, with 

findings that include: 

• Numerical models used to investigate changes due to the presence of large-scale tidal 

turbine arrays found that arrays in excess of 85 turbines have the potential to affect bed 

shear stress distributions (Martin-Short et al. 2015).

• 2-D numerical modeling of Shannon Estuary (a very unique estuary close to Limerick, 

Ireland) predicted that water levels and flushing parameters would be altered with the 

installation of arrays of current energy devices. With decreased device rotor spacing, 

inundation and increased residence times were identified, which could change habitat and 

pollutant transport in the region (Nash et al. 2014).

• Measurements of sediment type and bathymetry were collected at a site in the Irish Sea. 

A high-resolution, unstructured morphodynamic model and a spectral wave model were 

developed to quantify natural variability due to tidal and wave conditions. The impacts of 

tidal-stream energy extraction using the morphodynamic model were simulated. The 

results suggest that the sedimentary impacts of “first generation” tidal energy converter 

arrays (i.e., less than 50,000 kW) at this site are within the bounds of natural variability 

and are, therefore, not considered detrimental to the local environment (Furness et al. 

2012). Devices currently under development and permitting in the United States are 

typically less than 100 kW, 3 orders of magnitude smaller than the modeled array size. 

Numerous studies are available as part of the Tethys Knowledge Base, which can provide 

examples of data collection, analysis, and modeling efforts for wave, current, tidal, and more 

generic MHK technologies. Additional analysis for associated technologies, such as scour 

analysis associated with offshore wind installations, are also included. 

2.4.2 Known Unknowns

Several areas of concern regarding the wider impacts of MHK technologies on regional systems

are not well understood: feedback to regional ecology; defined impacts on habitat of species of 

concern; and the potential effects on far-field regional circulation, seabed, and water quality from 

larger-scale MHK deployment.

Measurement technology and protocols are continually being upgraded and developed, including 

unique tools that are being improved to inform modeling of seabed stability, sediment transport, 

and ocean energy impacts. These models include information collected from tools such as the 

SEDflume (Roberts et al. 1998), ASSET Flume (Roberts, Jepsen, and James 2003), and 
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SEAWOLF Flume (Jepsen, Roberts, and Gailani 2004) for sediment erosion testing; sediment 

profile imaging for benthic monitoring (Nilsson and Rosenberg 2000); and other available 

oceanographic monitoring tools. These tools are also being developed with increased 

functionality to asses conditions such as extreme storm events.

2.4.3 Unknown Unknowns

Largely unknown effects include the potential impacts of salinity and temperature stratification 

or mixing due to the devices and the resulting impacts that this might have on birds and other 

non-aquatic species.

2.4.4 Summary and Paths Forward

In summary, the following conclusions are appropriate given the current state of research in this 

area:

• Quantitative methods, including measurement and modeling, can be used to evaluate the 

effects of MHK arrays in coastal regions and rivers. 

• Modeling can be used to predict the potential changes to waves and/or water circulation 

for wave, tidal, and current devices. 

• Numerical evaluations show that small arrays (~10) of current or wave energy devices 

have minimal effect on the physical environment, although site-specific conditions and 

technology will drive the potential impact. 

• As array size increases, effects will likely increase and require further study.

• As the array size decreases, effects will likely decrease, especially for projects that are 

expected to be operated for short periods of time. 

• Devices in coastal near-shore locations may potentially be used to enhance coastal 

sediment management programs.

• Small arrays of current energy devices will likely have localized effects on potential 

benthic habitat and the water column, with minimal effects far-field. 

• The deployment of a small offshore array (~10) of wave energy devices will have 

minimal near-field effects on sediment dynamics and circulation and minimal potential 

for affecting far-field transport patterns of sediment, flow, and wave dynamics. The 

installation of single units for defined short time periods will again likely have very 

limited, if any, long-term impacts.

• Initial evaluation strongly suggests the most appropriate path to consider for progressive 

development and evaluation of impacts, especially for the development of small-scale 

arrays of MHK devices, includes adaptive management strategies with up-front site 

characterization, analysis, and then appropriate monitoring leading to flexible 

management.
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• The studies to date indicate that site-specific analyses where stratification is present and 

important to local ecology are useful and do typically provide an accurate assessment of 

potential impacts such as water flow and sediment transport. Tools exist to study these 

effects (such as SEDflume, ASSET Flume, SEAWOLF Flume, and SPI camera), and the 

linkage between physical and ecological processes is being further developed.

Determining whether a direct local assessment is needed remains a project-by-project 

assessment; however, numerical modeling of small arrays of devices shows limited near- and farfield impacts. The implementation of small-scale devices, especially for short periods of time, is

not expected to have noticeable impacts on physical processes such as overall sediment transport, 

water flow, and ocean/wave energy. For projects in which more detailed assessments are needed, 

modeling tools and guidance for the application of these tools are being deployed to provide easy 

end-user applications for site-specific evaluation.

3 Topical Summaries

In addition to the introductory and technical topics explored above, workshop participants and 

experts discussed other influences on MHK technology development and deployment. They 

reflected on lessons learned from the wind industry, heard from MHK industry members, and 

considered the applicability of adaptive management practices. Following are summaries of the 

materials presented and discussed.

3.1 Lessons Learned from the Wind Industry

The growth of the U.S. wind industry over the past 40 years presents some lessons that are 

appropriate for the potential development of the MHK industry. Without delving into a more 

exhaustive history of the development of the wind industry, enough parallels exist to offer the 

following lessons: 

A collaborative approach involving the key stakeholders facilitates an understanding of the 

potential impacts so that appropriate mitigation and monitoring strategies can be developed 

and implemented and the technology can advance, conceptually leading to cost-effective 

development. Some key points include: 

• Early and frequent engagement with all appropriate stakeholders builds trust and 

collaboration, which will help address ongoing or new unforeseen issues as the 

development process unfolds. Stakeholders could include regulators, members of 

industry and environmental groups, the fishing community, etc. 

• Data on impacts can be shared while respecting company intellectual property and 

industry-wide competitiveness.

• Quantitative science-based research with independent science-based oversight as a 

starting point is important to address identified issues, including a need to pool funds to 

conduct required studies to address identified or potential problems early in the 

development process. 
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• In the wind energy industry’s early years in the United States (primarily through the late 

‘80s), there was a great deal of mistrust among environmental organizations, 

environmental regulators, and the larger wind industry. Some of this mistrust lingers 

today. Even into the early 2000s, project development was seen as needing limited 

community engagement. The development of the National Wind Coordinating 

Collaborative, the Utility Variable Integration Group, and DOE’s deployment and 

education efforts helped articulate potential impacts more clearly and supported expanded 

community engagement. Expanded collaborative efforts by the American Wind Energy 

Association and the American Wind Wildlife Institute demonstrate more recent efforts to 

bring disparate organizations together to confront challenging issues. The quick launch of 

the Bat and Wind Energy Cooperative once wind turbine and bat interactions were 

identified as an issue is a good example of how building trust prior to the identification of 

a problem can help lead to faster collaboration and understanding of the issues and more 

informative impact mitigation.

MHK technology needs to evolve to become competitive. The wind industry has achieved a 

miraculous metamorphosis over the past 40 years. Starting with small turbines on low towers in 

the late 1970s, the cost of wind energy has decreased from about $0.80/kWh to $0.05/kWh at the 

best sites. Turbine development has also changed dramatically, from fabrication in machine 

shops to manufacturing in industrial-scale production facilities costing hundreds of millions of 

dollars. This metamorphosis, however, was built on a successive series of technology 

deployments, allowing rapid learning and design refinement (Figure 3). 

The ability to conduct this deployment/testing/re-deployment cycle across many projects enabled 

wind energy to develop rapidly. The process included testing at defined test sites, such as the 

National Wind Technology Center; at company test sites; and most important, as part of 

commercial project deployments. Due to the lack of accurate system models and a limited 

understanding of wind system dynamics, equipment testing greatly assisted early wind turbine 

design efforts. 

Baseline studies to measure and prioritize wildlife impacts have greatly supported wind energy 

development, while the lack of these studies early in the development process resulted in poor 

deployment decisions and unnecessary (in hindsight) impacts. A small number of early projects 

cannot identify all impacts, and it is impossible to foresee, and thus study, some of the impacts 

that only wider-scale deployment will illuminate. These conceptually opposing issues require a 

balanced approach, one that the wind industry faced as the technology developed and one that 

the MHK industry now faces. Limited oversight and study allow real issues to be missed or 

dismissed until they become large and potentially crippling problems. At the same time, too 

many early pre-full-scale projects and ongoing assessment of the potential impacts limit the 

ability of the technology to evolve and deploy into new areas where new issues will arise. Either 

extreme leads to a failed industry, resulting in the loss of a technology which may help reduce 

the overall high level of impact that other energy generation technology currently pose on the 

planet and its inhabitants. A balance between light-handed regulation of small-scale development 

paired with ongoing broader research and development, and a heightened ongoing sensitivity to 

potential problems and strong collaboration, will help identify issues and more quickly address 

them as they emerge. 
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Figure 3. The evolution of commercial wind technology

A wind industry example of this approach is the understanding of wind turbine and bat 

interactions. After almost 30 years of active turbine operation and the installation of tens of 

thousands of turbines, in the early 2000s the first projects installed in new areas highlighted bat 

interactions as a potential issue. The community is making progress and addressing this issue. If 

the industry had to tackle this issue as one of many hypothetical impacts in the early years, there 

would have been no way to assess the impact and potential mitigation options. 

Assess avoidance and mitigation options as early as possible. Although this may seem obvious, 

a high level of trust and collaboration is required to engage and solve problems. The first step is 

always being able to identify a potential issue with limited concern of potential liability, being 

open to scrutiny, and stakeholders being willing to support the research required to identify an 

acceptable and timely solution. A confrontational attitude only leads to retrenching and 

avoidance of the issues, making them harder to address. 

The issues around wind turbine and bat interaction provide another positive lesson from wind 

energy development. Following the identification of the issue, the formation of the Bats and 

Wind Energy Cooperative led to co-funded impact research and, most recently, the development 

of mitigation strategies and technologies. However, 15 years after the problem was first 

identified, acceptable solutions are just being realized. This process timeline could be shortened 

if appropriate collaborative mechanisms were in place to allow more rapid progress.

The size of the companies engaging in new technology development limits their ability to 

address known issues at early industry stages. All of the companies that started the wind 

industry were small, with few remaining active in the market. The ability of these companies to 

engage in detailed impact studies was limited, and in the case of early wind development, the 
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studies were largely not required. This lack of regulation helped speed technology development, 

but it meant that the industry could largely ignore growing issues, resulting in a reputation that 

the industry still works to overcome. As the wind industry has grown, so has its ability to support 

research and technology programs to mitigate identified impacts such as sound levels, avian 

impacts, and bat fatalities. As noted earlier, in recent years the industry has also been able to 

fund collaborative organizations addressing known issues, such as the American Wind Wildlife 

Institute. The lesson is that the condition and capabilities of the industry must be weighed as part 

of the regulatory process. Too much regulation and it will be impossible for the industry to 

advance—driving it to extinction or at a minimum, out of the United States. Too limited 

regulation allows the industry to sidestep important questions that in the end will be bad for the 

environment and bad for the industry. Finding a balance to achieve both needs and sorting 

through what is appropriate through broader collaboration and what is appropriate for individual 

projects at different stages of development are important for success. 

Global market potential makes a huge difference in supporting technology development and 

understanding potential impacts. A large potential market is critical to attract private or public 

funding to address issues, spur research, and allow technology development to progress to 

commercial development. The wind industry, like the MHK industry, has clear market drivers 

and a wide market potential if the technology cost is competitive with other energy sources. 

However, this wide market can hinder development if every potential impact in each market 

must be understood or measured to document impacts prior to early project deployment, 

especially while the industry is still small and undercapitalized.

A strong federal role is needed to support ongoing technology innovation, development, and 

impact assessment. The energy sector is relatively unique because of the role federal and state 

governments have in its regulation and support, either directly or indirectly, to allow continued 

innovation. Federal organizations can also play a unique role as independent third-party 

collaborators, with the ability to not only support the resolution of long-term issues but also to 

identify parallels and shared experiences. The difficult lessons from the relatively new wind 

industry should be considered by technology developers, project developers, and the regulation 

community to enable smooth development of the fledgling MHK industry. 

3.2 Differences that Could Slow Industry Advancement

Although it may be possible for MHK technologies to follow a similar, though better informed, 

path as wind technology, there are a few differences between the current MHK and early wind 

industries that are important to note in the context of this document: 

• Cost of early device testing: Although developing and testing wind turbines in the wind 

industry’s early stages were expensive, they were significantly less costly than 

completing similar work in the marine environment. From the simple logistics of 

deploying similar-stage technology to the ability to closely watch and record operation 

during extreme events, land-based deployments are much less costly. Given the available 

resources of the current MHK and early wind industries, this is a significant impediment. 

• Complexity of the testing environment: Adding to the high costs, measurement 

equipment to understand the system and the system environment is much more complex 

and costly in the marine environment. Additionally, given the complexity and limitations 

forced by the environment, any data collected may be harder to analyze or interpret.
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• Regulatory landscape: During the early years of wind development, there was very 

limited regulatory oversight, especially for projects on private land. This situation 

allowed for rapid testing and technology development. Similar testing of pre-commercial

MHK technologies can take many months of regulatory engagement to seek approval, 

including the need to receive additional approval for any major change in the testing or 

system configuration. These regulatory requirements will slow the development process, 

including the refinement of measures that could help the industry reduce potential 

impacts.

How these items play out over the next 20 years will likely determine how well MHK 

technologies develop, both domestically and internationally. 

3.3 Information and Perspectives from Industry

This section outlines key points identified from interviews conducted prior to the workshop with 

representatives from U.S. MHK device companies.

3.3.1 Project and Regulatory Perspectives

As MHK technologies are not yet at commercial readiness, present MHK “project development” 

is very different from present project development of commercial or near-commercial 

technologies such as wind power. Because of the complexity of the permitting process and lack 

of defined test centers, technology developers are being forced into the role of project developers 

to allow testing of pre-commercial units, further stretching the resources of these small 

companies. The implementation of defined test centers will help to alleviate some of this 

complexity as test centers will have many permits already in place and expanded environmental 

and regulatory related expertise on staff to support the assessment of individual applicants. 

MHK technology developers are now deploying devices so they can work with researchers and 

regulators to validate computer design models/designs; identify key areas for performance, 

reliability, and environmental interaction improvements; get experience to inform optimization 

of installation and operation; optimize and demonstrate performance and environmental 

compatibility; and obtain data for technology certification. These activities are required to 

develop commercial-ready, sustainable, MHK renewable energy systems with minimal 

environmental impacts. 

MHK industry representatives posed a number of questions (see Appendix E) regarding the 

regulation process and identified the following general themes for a successful path forward: 

• Find ways to install projects that allow manufacturers/developers to improve the 

technologies while obtaining operational experience and learning and understanding 

potential impacts

• From these experiences, improve ways to minimize and avoid impacts.

3.3.2 Themes from Industry: Objectives

The MHK industry fears that the extensive permitting requirements and long permitting 

timelines will impede the exploration of the potential of MHK technologies to produce 

renewable energy sustainably and support climate change objectives.
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Near-term desires from MHK technology developers include: 1) Consistent leveraging of 

relevant existing information, models, and best measurement practices to establish risk-based 

baseline site understanding, and 2) Adoption of adaptive management practices to enable single 

and small arrays of devices to be deployed, allowing the level of technical and environmental 

impact learning that must be undertaken to allow the industry to responsibly develop. 

3.3.3 Themes from Industry: General Process

General themes of lessons learned from the direct regulatory experience of MHK project 

developers and test centers have emerged. All organizations recommended early engagement 

with a broad group of stakeholders to identify all potential project challenges. It was also 

recommended that clear and effective lines of communication are established to build and 

maintain trust. All parties must be honest and open, understand regulatory needs and constraints, 

and deliver on commitments. Other recommendations include clarify regulatory requirements 

and study needs as soon as possible; initiate adaptive management discussions early in the 

process; and deliver informed, detailed project applications. 

Industry representatives desire that regulatory agencies encourage greater coordination and 

information sharing among agencies. Industry parties also noted that insufficient intra-agency 

coordination (e.g., connections between different regional offices and headquarters) has also 

been a challenge. 

3.3.4 Themes from Industry: Risk

Industry representatives questioned whether imposed data requirements from regulatory agencies 

are always risk-based. The overall perception was that the uncertainty of long-term effects, 

especially from arrays of devices, has been driving many data asks for single, short-term device 

deployments. The general feeling was that the MHK industry was being held to different 

standards for similar potential impacts (e.g., EMF emissions, acoustic noise) than established 

industries. 

The MHK industry has a strong desire for regulatory agencies to collectively identify which 

perceived risks are the most important and to articulate a methodology or research process to 

address them. This would include articulating the remaining risks associated with single or small 

arrays of MHK devices, what definitive studies are needed to address lingering questions around 

different potential impact areas, and the expected conclusions or defined criteria to determine 

whether the studies are successful. The industry is interested in working with state, regional, and 

national regulatory organizations to ensure that the findings of studies that have addressed 

identified risks are reported and, if additional risks have been identified, what additional studies 

are required. 

3.3.5 Themes from Industry: Data Sources

Questions persist regarding the use of previously completed studies and data applicability across 

the MHK industry. For example, understanding how to effectively use relevant existing data is 

another strong industry desire, including ensuring that global observations and relevant data from 

other industries are being utilized in assessing U.S. project risk. 

Additional topics that are being discussed include what is appropriate for modeling based on 

external or point measurements (e.g., how acceptable are encounter probability models and how 
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such models can be validated, especially when observational data can be hard to obtain). Because 

MHK technology deployment is still new, additional data- and study-related questions remain, 

such as accepted protocols/best practices and measurement technologies to ensure, to the extent 

possible, consistent and accepted study results across technologies, species, geographies, and 

also between agencies. 

3.3.6 Themes from Industry: Monitoring Requirements

Overall, the industry representatives interviewed believe that the present level of required 

monitoring for single devices, especially for short-term deployments that are typical of testing 

for technology development, is not aligned with the associated risks nor with what can be learned 

based on the proposed activities. The industry’s objective would be adaptive management and 

monitoring around remaining risks with thresholds for contingency action. 

3.3.7 Themes from Industry: Pre-Permitted Test Centers

There is a strong desire to establish pre-permitted test centers to make it efficient for MHK 

technologies to begin operating and collecting data, enabling them to mature in reliability and 

performance in as environmentally benign a manner as possible. These test centers could also be 

leveraged to better understand/retire some single-device and small array risks.

3.4 Adaptive Management Case Studies

Adaptive management is not a new concept; the practice of studying something and making 

changes to address identified problems is a powerful tool applied in many permitting schemes. 

Definitions of adaptive management are diverse and varied, including: 

• “A systematic approach for improving resource management by learning from outcomes” 

(Williams, Szaro, and Shapiro 2009, p. 1) 

• “[A]n iterative approach to managing ecosystems, where the methods of achieving the 

desired objectives are unknown or uncertain” (California Coastal Commission 1995) 

• A process for “evaluating the performance of new management approaches and changing 

practices over time as experience is gained” (West Coast Environmental Law Glossary 

2016).

3.4.1 Green-Versus-Green Regulatory Challenge

From the MHK development community’s perspective, some of the environmental policies and 

processes that drive renewable energy development and those that protect the environment are 

not well aligned. Climate mitigation is one of the drivers for expanded renewable energy 

development, which can reduce or offset larger environmental impacts, but then renewable 

energy projects face substantial barriers from natural resources protection regulation. Balancing 

the priorities of allowing MHK technology development with its longer-term, positive 

environmental impacts while honoring the regulatory agencies’ different drivers and defined 

roles continues to be a challenge. Adaptive planning and management strategies and practices 

have the potential to be one tool that can reconcile these discrepancies, supplementing and 

enhancing the precautionary principle in wildlife planning for green energy (Koppel et al. 2014). 
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3.4.2 Perspectives in Adaptive Management in MHK

The perspectives on adaptive management in MHK by the regulatory agencies and the industry 

are an important contextual element for the development of effective adaptive management 

programs going forward. Until the risks to the marine environment from MHK projects are better 

understood, regulatory agencies must take a conservative approach to protection of listed species 

and their habitats. Ideally, information gained from small-scale projects will also be useful for 

understanding potential effects as projects scale up while allowing for the development of 

alternative design approaches that may reduce or eliminate impactful design elements. However, 

the challenges to studying small-scale projects need to be considered from a basic cost and 

technology development timeline perspective. The role of and process for adaptive management 

must be clearly defined and focused. Industry should focus on known high-probability, higherrisk impacts for which successful, targeted monitoring methodologies are available to assess and 

evaluate minimization and mitigations. Impacts for which the risks or impact severity are 

relatively unknown, monitoring approaches are experimental or untested, and other more 

challenging topics should be addressed through defined, co-funded research projects 

incorporating the organizations most likely to allow successful and scientifically valid 

conclusions. 

Although there is an inherent desire to use the deployment experience from single or small-scale 

deployments to inform potential larger-scale deployments, the industry feels strongly that 

knowledge gaps of potential impacts of large-scale array deployment cannot be filled 

substantively by information collected for short-term, single-device, or small-scale deployments. 

Participants noted that the flexibility inherent in adaptive management helps in the permitting 

process but can challenge project financing if not well defined and bounded because it can add 

significant uncertainty.

3.4.3 Ocean Renewable Power Company Case Study

ORPC presented a brief case study of adaptive management utilization on its Cobscook Bay 

Tidal Energy Project, which included the deployment of a single TidGen® device. ORPC’s 

regulatory concerns included the Endangered Species Act, the Magnuson Stevens Act, and the 

Marine Mammal Protection Act. A broadly represented and knowledgeable adaptive 

management team used best science-based data collection and analysis, and frequent and 

transparent communication to develop and implement an adaptive management plan. This 

resulted in such actions as the removal of seasonal restrictions for pile driving based on 

mitigation methods and measured acoustic levels and a reduction in frequency or elimination of 

specific monitoring surveys based on increased knowledge of species presence and 

environmental effects.

3.4.4 Verdant Power Case Study

Verdant Power’s Roosevelt Island Tidal Energy (RITE) Project is a multi-year pilot MHK tidal 

development, deployment, and educational process with 26 agencies and more than 50 nongovernmental organizations involved and more than $4 million in environmental studies and a 

committed $2.3 million in future RITE Project Monitoring of Environmental Effects plans 

(Verdant Power 2016). 
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Verdant’s project case study was the staged development of up to 30 turbines in the East River in 

New York City. Regulatory agencies perceived the primary risks to be the effects of multiple 

turbines and the behavioral aspects of species movement and migration over years. The adaptive 

management objectives of the RITE project were to relate risk, cost, and knowledge obtained to 

the size and scale of the project. The monitoring plan, which was established during 

developer/agency negotiations at the draft license application phase, expands as the number of 

machines increases. This plan results in refining ongoing monitoring, and where findings 

substantiate, eliminating future monitoring. In January 2012, FERC issued a pilot commercial 

license (FERC No. P-12611) for the installation of up to 30 turbines, although to date no turbines 

have been installed. 

Verdant’s adaptive management philosophy has the following components: 

• Monitor operations: Apply best known techniques 

• Adjust monitoring: Interactive discussion of data with all relevant regulatory parties 

leading to adjustment of monitoring parameters and technology as needed 

• Adjust operations: Understanding that the ultimate purpose of the project is to generate 

electricity and adapt operations when necessary based on measured impacts and 

discussion with relevant regulatory organizations 

• Stop/remove: Again based on monitored observations and discussion with relevant 

regulatory organizations, remove the equipment if mitigation or minimization strategies 

cannot be identified. 

Verdant’s current perspective is that a Catch 22 exists: How can you understand the effects if 

you don’t test, and how can you permit testing if you don’t know the effects? The applied 

adaptive management strategy should help address this paradox. 

To enable successful MHK deployments, Verdant staff suggests establishing a small, 

knowledgeable working group of geographic diversity regulatory agencies to address larger 

questions of appropriate regulation. They recommend matching prioritized natural resource

issues to monitoring scales and developing monitoring methods and protocols to answer these 

specific uncertainties. Verdant recommended that adaptive management be implemented in a 

staged but defined manner. Based on their experience, Verdant staff believes that the MHK 

regulatory process is streamlined by the FERC pilot regulatory process but felt that bilateral 

(both agencies and the developer) awareness and participation during pilot operation is essential. 

The company’s representatives also support the parallel funding of long-term macro studies by 

academia and DOE labs to support implementation of a U.S. industry. 
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4 Research Needs and Knowledge Gaps Discussion 

Summary

The workshop presentations and discussions provided background for discussion of research 

needs and knowledge gaps. As part of this dialog, a synthesis of the earlier presentations 

provided guidance for the group; several themes emerged, including: 

• There should be a distinction between research needs and knowledge gaps that should be 

addressed as a permit requirement. Monitoring and adaptive management should be 

conducted where uncertainties and risk are high. Research should be conducted 

collaboratively between researchers, agencies and industry, but ultimately there should be 

an open discussion about who should bear the responsibility to address and fund research 

versus knowledge gaps that can affect permitting. 

• The need for extensive baseline and effects monitoring and studies when project effects 

are likely to be negligible or indiscernible is likely not warranted. 

• Topic areas in which environmental effects are already reasonably understood need not 

undergo extensive monitoring. 

• The role of modeling or simulations to provide reasonable bounds for uncertainty should 

be readily applied as an initial approach to addressing potential impacts. 

In all of these cases, any required monitoring should apply the concept of proportionality, in 

which the potential risks are linked to the baseline information needed and monitoring, followed 

by adaptive management, is applied commensurate to the risks. 

Table 2 provides an overview of the resulting discussion in relation to the four areas addressed as 

part of the workshop. 

4.1 Collaborative Interchange of Project Permitting and Research 

There is a need to be cognizant of these knowledge gaps given the realities of what we: 

• Must know for obtaining project permits 

• Would like to know because of uncertainties and scientific interest (e.g., research) 

• Can actually feasibly evaluate giving consideration to the cost, the risks to resources, size 

and scale of potential effect given natural variability, and feasibility of getting sufficient 

information to adequately address hypotheses and objectives. 

The overarching issue is that the monitoring cost is high, including the equipment, 

implementation, upkeep, and information processing. The relevance of the information gained 

being applied to the resolution of high-risk issues associated with a project under permit should 

lead the need for monitoring and how monitoring is funded.
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Table 2. Recommendations for Monitoring and Research from Workshop Presentations and 

Discussions

Monitoring for Single 

Devices/Demonstration-Scale Projects

Research for SingleDevice/Demonstration-Scale or 

Commercial-Scale Projects

Operational 

Noise 

• Information collected to date indicates

that operational devices are typically

less noisy than other anthropogenic

sources.

• Monitoring is generally not warranted

as significant acoustic impacts are

unlikely and difficult to distinguish from

background noise.

• Data collection at demonstration

scales may be appropriate, if

detectable, to inform modeling for

larger-scale arrays.

• Research on biological and

behavioral implications of sound

and particle motion would be

helpful.

Electromagnetic 

Fields

• No significant effects to organisms

have been observed to date.

• Monitoring is generally not warranted

since EMFs are likely to be low

intensity and approach background

levels within a few meters from the

source.

• EMF emissions are relatively

scalable as power and voltages

increase but the responses of any

receptive animals are not; thus

research on single devices or smallscale arrays may not be directly

transferable to larger-scale projects.

• Existing energy subsea cables can

be utilized to assess EMF levels

and animal behavioral responses.

Physical 

Interactions 

(Strike)

• No physical interactions have been

observed in the field. Lab experiments

have found that fish can easily detect

and avoid or swim around turbines and

have very high survival rates when

forced to pass through turbines.

• Any required monitoring should be

based on risk posed at the project of

interest and should consider that strike

events are likely to be rare, difficult to

detect, and very costly to monitor.

• Research to better understand the

risk of strike and development of

predictive models (e.g., location in

the water column relative to the

device, avoidance and evasion

behaviors) and identification of

potential mitigation actions would be

helpful.

Impacts on 

Physical 

Systems

• Numerical modeling consistently

predicts that arrays <10 devices will

have minimal impact on wave heights,

flow patterns, and sediment transport.

• Monitoring is generally not warranted

as impacts from a single device or

small arrays will likely be minimal.

• Impacts of larger arrays are

unknown and will require more

research. Data from eventual large

arrays are needed to validate

predictive models.

For the purposes of the workshop and this table, “monitoring” was defined as activities required of the 

developer by federal, state, or local entities to assess project impacts during operations and to fulfill legal 

regulatory obligations. The level of monitoring should be based on the level of assessed risk/potential 

project impact posed by the project in question and should be directed to address specific objectives.

“Research” is performed to fill gaps in understanding and answer questions beyond those required to meet 

fundamental legal or regulatory mandates. Research is typically performed by academia or government 

agencies.
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The group discussed four key questions, concluding: 

The need for an umbrella collaborative or organization to serve as a central clearinghouse 

for global research and monitoring needs within the MHK industry. The collaboration 

among industry, scientists, agencies, and environmental groups can set the stage to resolve 

remaining environmental issues by researching technology innovations, providing science to 

support policy and decision-making, and providing for information exchange to decrease 

uncertainties. 

• A spectrum of collaboration could be considered, ranging from the collection of research 

projects (as demonstrated by the Tethys Knowledge Base); coordination of international 

research (such as the OES Annex IV); coordination and collaboration, including the 

development of research roadmaps (as has been conducted by the American Wind 

Wildlife Institute); or an organization that consolidates and then funds research 

(exemplified by the Bats and Wind Energy Cooperative). 

• As some experts indicated, there is a need to share information gathered at specific 

projects with the research community so that models and their predictive capabilities can 

be improved upon to allow application to address environmental uncertainty for future 

projects and project build-out scenarios. 

• The idea of a public-private partnership, in which industry can provide data for specific 

topic areas to researchers, should also be considered. Also by pooling expertise and 

funding, it may be possible to support research projects to address larger questions that 

affect multiple projects. 

• There are significant differences among regions regarding the level of monitoring and 

obligation of industry. In addition, the onus on industry to evaluate potential 

environmental effects seems out of proportion to the environmental risks. Understanding 

the continuum of risk, including the potential for impact and the effects of those impacts, 

could be a role that a collaborative group could address. 

Because natural variability in marine environments is high and events/interactions of 

concern are likely to be rare, the ability to detect effects using traditional monitoring tools 

is very low. Monitoring approaches and technologies, especially those that need to detect 

relatively rare events, are under development but are not yet readily available. 

• There is a need to develop monitoring technologies that can be deployed in harsh ocean 

conditions over long time periods, can perform reliability at all time periods (e.g., some 

effects may only occur at night where light levels are low or only during high sea states), 

and can provide that information in a timely manner. 

• The development, demonstration, and validation of new monitoring devices should be 

performed in a collaborative research setting, with biologists, engineers, and others 

working to develop the technologies and approaches for data gathering, data storage and 

analysis, and interpretation. Permitting authorities should consider this issue when 

determining monitoring needs for a specific project. Some questions cannot be 
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adequately addressed through methods and instrumentation that are currently available 

without tremendous effort and cost. 

A NEPA database could provide a useful source of information for future project 

permitting. NEPA is a requirement for project permitting; therefore, a focused impact study is 

conducted on every project. As more projects get permitted, the environmental analyses should 

become increasingly informative and uncertainties should decrease (either because no or 

minimal impacts are found or because adaptive management enables ways to identify impacts 

and avoid, minimize, or mitigate impacts). 

Addressing research needs and knowledge gaps through studies and monitoring can be 

very costly, so it is necessary to consider how the available limited funding could help inform 1) 

improvements to models/simulations to increase certainty and predictability, 2) future/new 

projects, and 3) scale issues (e.g., commercialization from small-scale to larger arrays). 

• The group felt that the issue of EMF emissions is sufficiently complex and has far too 

many uncertainties (especially understanding the ability of animals to detect projectgenerated EMFs and their behavioral responses at the power levels of current MHK 

devices) and that it belongs in the research realm using a collaborative approach, rather 

than evaluating effects on a project-by-project basis. In addition, studies on animal 

detection and behavior are best done in laboratory and experimental field settings where 

factors can be controlled for. 

• Sound generation was another area where baseline information is important because 

sound will be site-specific due to background anthropogenic sources, seabed 

composition, bathymetry, and other factors. However, the collection of baseline 

information is likely only necessary when trying to understand how the acoustic 

condition for a site has changed, based on deployment. It is not anticipated that this will 

be necessary for small-scale and/or temporary installations. Such baseline studies may be 

helpful to advance modeling efforts and improve predictive capability for future projects 

or commercialization. To put sound into context, there needs to be an understanding of 

the potential impact at different sound levels, risks to species of concern, and how to 

determine mitigation actions when sound becomes a concern. 

4.2 Needs for Site Characterization and Environmental Baseline 

Assessment

As part of project permitting, there are requirements for site characterization and environmental 

baselines from which to evaluate potential project effects. Many of the presenters indicated that 

for small-scale MHK projects (e.g., <10 devices), many of the potential environmental effects

(e.g., entanglement, behavior/use, reefing, benthos, EMFs) are likely either negligible and/or 

predictable at this scale. The group discussed three follow-up questions: 

Do we know enough about some topics to be able to permit/license sites without baseline 

assessments? 

• Workshop participants discussed issues at the small project scale that would require

baseline studies. For smaller or temporary projects, there was consensus that we have 

sufficient information on the potential effects/levels of EMFs, benthic disturbance, and 
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effects to seabirds at tidal turbines to not warrant baseline monitoring at this scale.

However, some site characterization and baseline monitoring will be important for 

addressing potential for certain project effects, including ambient acoustic measurements, 

identification of species that might be susceptible to tidal turbine blade strike (e.g., which 

species/life stages and probability/timing of presence) to inform strike risk models, and 

characterization of benthic environment to inform physical model/simulations. 

• In addition, participants recognized that BOEM is conducting baseline biological 

monitoring of the outer continental shelf that should be helpful for characterizing specific 

biota (e.g., seabirds, benthos), which should decrease the amount of additional baseline 

monitoring for a project at a given site. BOEM- and DOE-supported syntheses will also 

be helpful for providing the state of the science, which should inform additional needs for 

baseline monitoring. 

What thresholds are there to indicate that a baseline assessment is insufficient for permitting 

and additional field studies should be undertaken? 

• Acoustic thresholds have been suggested for some animal groups, and baseline 

monitoring should inform pre-project levels of sound to put thresholds and project effects 

into context. 

• However, for other baseline needs there are no available thresholds for permitting or 

identifying needs for continued or additional field studies. The regulatory agencies and 

developers should work together with scientists to develop realistic monitoring objectives 

considering the level of effort needed to document an effect (e.g., is baseline monitoring 

being conducted to evaluate effects after project installation, and if so, are the methods 

and monitoring technology appropriate to detect changes?). It is important to address 

these objectives such that once monitoring results indicate environmental effects are 

within an acceptable range, monitoring can cease or be scaled back appropriately. 

• Furthermore, monitoring objectives should focus on environmental effects that are likely 

to have high uncertainty and a high risk to resources. Monitoring should focus on times 

or seasons, or locations, when/where risks are greatest. An adaptive management process 

would be a good means for implementing monitoring and evaluation of results. 

How many years of baseline information are needed? 

• The number of years of baseline observation will depend on the objectives of the baseline 

effort. If the objective is to provide site characterization information, less than 1 year may 

be sufficient depending on what is known about the location in question. However, if the 

purpose is to provide baseline for a before-after-control-impact study, then several years 

may be necessary. For example, evaluating whether species avoid a project area after 

implementation may require more than 1 year establishing pre-project use of the project 

area. The length and goals of the expected deployment should also be considered, 

however. Conducting extensive pre-project deployment to understand current use is 

unnecessary if the deployment is limited in size and scale such that avoidance would be 

difficult or impossible to detect. 
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4.3 Role of Modeling and Simulation to Address Uncertainties

For many potential project effects, modeling and simulation can help address or bound 

uncertainties. For example, what effects can be modeled or simulated with sufficient robustness 

(e.g., EMFs, acoustics, strike, physical environment)? Can such modeling substitute for baseline 

and effects monitoring for informing environmental impact assessment and ESA consultation? 

Understanding that model validation requires observational data, are we at a stage for model 

development in which further investment of research funding would be better spent in 

developing and validating models as compared to conducting more field measurement (i.e., 

should we focus on the sensitivity of specific model parameters that affect model predictions for 

effects that are well understood compared to the collection of additional field data from more 

geographic locations)? 

• Strike and collision modeling should be able to characterize the risk for small or large 

projects, using simple baseline information such as species, probability of presence, and 

project location in the water column, similar to what has been done for wind projects. 

One consideration is that models could be parameterized collaboratively by researchers, 

industry, and regulators so that there is agreement on the ranges of model parameters, 

allowing a stronger focus on the sensitivity of parameters that have the greatest effect on 

model results. 

• Although it is likely that small-scale projects will have minor impacts to the physical 

environment, collecting information at projects would be useful to improve relevant 

models, especially for application toward commercial development. However, extreme 

care must be taken from a regulatory perspective in differentiating between data that 

should be collected as part of the regulatory monitoring requirements and data that could 

be collected opportunistically when deployments occur that will help advance the 

industry as a whole. Since opportunistic data collection would go beyond the needs of the 

permitting of specific projects, this is a good example of research/industry collaboration 

for addressing knowledge gaps by providing project-specific information and pooling 

resources. 

• EMF modeling (generation of EMF by a project) has the potential to support or replace 

the use of measurement data, but models have to be validated first; current information 

indicates that models are reasonably accurate. It would be helpful to conduct 

opportunistic project-specific monitoring to address uncertainty around existing 

measurement and modeling options. However, the uncertainty is greater with interpreting 

model outputs (e.g., the effects of differing levels of EMFs on organisms), which would 

require research in laboratory settings and focused field efforts.
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5 Conclusion

The workshop provided a good opportunity for regulators to hear directly from leading 

researchers and learn what is known and unknown regarding the deployment of MHK 

technologies. The ability for members of the regulatory community to engage in dialog with the 

researchers also helped expand their understanding of important topics, and collaborative 

discussion provided insight that can empower regulators to determine the appropriate level of 

regulation for the MHK industry. 

The general conclusion was that early device deployment baseline and monitoring requirements 

were not necessarily commensurate with the uncertainties and potential risks of specific smallscale deployments and that in some instances, too much emphasis has been placed on studying 

potential effects of large-scale array deployment as compared to assessing observable and likely 

impacts given the current deployment of single devices and small-scale arrays. At the same time, 

given the early stage of the technology’s development, the group discussed the need for 

continued research by government and academia to gain further understanding of potential 

project impacts at larger commercial scales.

Given the current understanding of risk levels associated with small and temporary project 

development, assessments of perceived risk and monitoring needs, combined with actionable 

adaptive management strategies so that any issues that are identified can be rectified or 

mitigated, should be applied. Without such an approach, the ability of MHK technologies to 

develop through a process of single-device and small-scale serial deployment, leading to a lowcost and low-impact technology that can be deployed at commercial scale, will be very difficult. 
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47 

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.

Appendix A: Annotated Agenda 

Following is a brief summary of each workshop session.

Regulatory Introduction: Roles and Responsibilities within the Permitting Process 

Speaker: Anna West, Kearns & West

Purpose: to provide a broad overview of the state and federal regulatory process. Topics explored 

included identifying the agencies involved in the permitting process and clarifying their roles and 

responsibilities, legal jurisdiction, focus areas, inputs to consider, and challenges they face in the 

application process. The presentation also reviewed the project permitting and licensing process. 

MHK Technology Overview

Speaker: Ryan Sun Chee Fore, U.S. Department of Energy

Purpose: to provide an overview of the primary MHK technologies and systems that are being 

developed to capture wave, tidal, ocean, and river current energy resources. The presentation 

focused on key operational concepts and impacts, as well as recent and existing demonstration 

projects and testing sites. Although no large MHK arrays have been deployed, Sun Chee Fore 

discussed contemporary research and the availability of wind research that could be leveraged. 

Introduction and Overview of Environmental Issues and Processes

Speaker: Sharon Kramer, H.T. Harvey & Associates

Purpose: to discuss the environmental issues and processes relevant to MHK energy generation 

and project implementation. This session explored current research and case studies on potential 

environmental effects, what has been measured and observed during the course of research, and 

processes for evaluating potential effects.

Physical Interactions with MHK Devices

Speaker: Jocelyn Brown-Saracino, U.S. Department of Energy 

Purpose: to present the current state of understanding of risks and issues associated with direct 

and indirect physical interactions among MHK devices and systems, moorings, electrical 

interconnections, and marine species. This session looked at the probability, consequences, and 

effects of strike events as well as survival rates and avoidance behavior in fish and mammal 

populations. 

Acoustic Output from MHK Devices

Speaker: Chris Bassett, Woods Hole Oceanographic Institute 

Purpose: to address the acoustic impact of MHK deployment and operation on ocean ecosystems 

and marine systems, providing a better understanding of sound variables and the measurement 

and assessment methodologies used to determine this impact. Areas with additional data needs 

and continued study were identified.
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Effects of MHK Development on Physical Systems

Speaker: Jesse Roberts, Sandia National Laboratories, and Craig Jones, Integral Consulting 

Purpose: to present the environmental effects of marine energy development on physical systems 

within the ocean space, including the change of local ocean ecosystems due to the installation of 

new MHK devices. Roberts and Jones discussed how the physical environment is changed, 

whether the changes are significant and cause for concern, and whether effective mitigation 

strategies exist.

IEA Annex IV and Tethys Database Demonstration

Speaker: Hoyt Battey, U.S. Department of Energy 

Purpose: to provide an overview of IEA Annex IV’s ongoing research activities on the 

environmental effects of marine energy devices and introduce the Tethys Knowledge Base of 

information on environmental effects of MHK and offshore wind development. 

Electromagnetic Force from Tidal and Wave Systems and its Impact on Marine Animals

Speaker: Andrew Gill, Cranfield University 

Purpose: to discuss undersea power networks and EMF emissions from undersea AC and DC 

cables and present the current state of knowledge regarding the effects of emitted EMFs from 

marine renewable energy cables on marine organisms. Field data and case studies from around 

the world helped establish an understanding of the interaction between EMF and a variety of 

species, as well as identified remaining questions requiring further research and measurement 

campaigns.

Lessons Learned from the Wind Industry

Speaker: Ian Baring-Gould, National Renewable Energy Laboratory 

Purpose: to review the growth of the wind industry and how lessons learned have altered site 

selection, regulation, and the application of adaptive management processes. Comparisons 

between the marine energy industry and the path of the wind industry were made and potential 

relevance of lessons learned were identified.

Federal and State Agency Roundtable: Perspectives on the Permitting Process

Moderator: Anna West, Kearns & West

Panelists: Casey Reeves, Bureau of Ocean Energy Management; Stephen Bowler, Federal 

Energy Regulatory Commission; Joshua Gange, Jeff Murphy, National Ocean and Atmospheric 

Administration; Jim Beyer, Maine Department of Environmental Protection

Purpose: to allow regulators to obtain a perspective from other regulators, supporting better 

collaboration and coordination between organizations at the state and federal levels. 

Representatives discussed current challenges and recommendations, baseline information, data 

gathering and monitoring requirements, as well as ways that both regulators and industry can 

approach a project to best navigate the process. 
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Information and Perspectives from Industry

Speaker: Al LiVecchi, National Renewable Energy Laboratory

Purpose: to discuss experiences with the regulatory process and monitoring requirements from 

the developer perspective. Questions and experiences related to inter- and intra-agency 

coordination, risk-based approaches, data sources, measurement protocols, and measurement and 

monitoring requirements were posed as participants explored what has and has not worked well 

in the past and what could be done differently in future projects. 

Adaptive Management Case Studies Roundtable

Moderator: Al LiVecchi, National Renewable Energy Laboratory 

Panelists: Nate Johnson, Ocean Renewable Power Company; Jim Beyer, Maine Department of 

Environmental Protection; Ron Smith and Mary Ann Adonizio, Verdant Power Inc. 

Purpose: to define adaptive management, explore how it has been applied in other industries, and 

highlight the challenges of implementation through the framework of recent MHK case studies. 

Participants and panelists also discussed recommendations for effective implementation of 

adaptive management and the role of project scope and scale in designing adaptive project 

approaches.

Breakout Discussions: Knowledge Gaps and Research Needs

Moderator: Sharon Kramer, H.T. Harvey & Associates 

Purpose: to consider the information presented during the workshop and identify remaining 

knowledge gaps and additional information needed to make regulatory decisions regarding MHK 

technology deployments. Participants discussed near-term and future regulatory information 

needs, how project scale influences potential impact and monitoring requirements, and how the 

burden of greater research needs should be addressed through efforts from government 

laboratories, agencies, and educational institutions. 
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Appendix B: Additional Session Information

Applicable Laws and Executive Orders

Section 1.3 referenced a list of more than 22 applicable laws and executive orders that are 

relevant to permitting and licensing MHK projects in the United States. The following list 

identifies those laws and executive orders:

• National Environmental Policy Act 

• Endangered Species Act 

• Marine Mammal Protection Act 

• Magnuson-Stevens Fishery 

• Conservation and Management Act 

• Marine Protection, Research and Sanctuaries Act 

• National Marine Sanctuaries Act 

• E.O. 13186 (Migratory Birds) 

• Coastal Zone Management Act 

• Clean Air Act 

• Clean Water Act 

• E.O. 13547 (Stewardship of Oceans, Our Coasts and the Great Lakes) 

• Ports and Waterways Safety Act 

• Rivers and Harbors Appropriations Act 

• Resource Conservation and Recovery Act 

• National Historic Preservation Act 

• Archaeological and Historical Preservation Act 

• American Indian Religious Freedom Act 

• Federal Aviation Act 

• Federal Power Act 

• E.O. 13007 (Indian Sacred Sites) 
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• Marking of Obstructions. 

Knowledge Gaps and Research Needs: Summary Table

During the Knowledge Gaps and Research Needs session, participants and topical experts 

identified major topic areas and discussed whether the burden of filling current knowledge gaps 

lies with industry or with public entities such as government research laboratories and agencies, 

regulating entities, or educational institutions. For the majority of topic areas and for smaller, 

temporary projects, participants concluded that the responsibility for filling the knowledge gap 

and meeting research needs was with public entities. A few areas required additional baseline 

data-gathering campaigns for site-specific information. Given the current state of technology 

deployment, knowledge gaps and research needs were not discussed for multi-device arrays. 

Table 2 summarizes this discussion.

IEA Annex IV and Tethys Knowledge Base

IEA Annex IV is an international collaborative project established by the International Energy 

Association’s Ocean Energy Systems,24 with 13 member nations involved as of February 2016. 

The goal of Annex IV is to examine environmental effects of marine energy devices and 

environmental research studies from around the world, making existing information available 

and accessible to marine energy researchers, regulators, developers, and stakeholders. 

One of the outcomes of the initial IEA Annex IV work to compile and disseminate information 

was the development of the Tethys25 Knowledge Base. The database is a knowledge 

management system that gathers, organizes, and disseminates information on the environmental 

effects of MHK and offshore wind energy development. The information provided is not limited 

to literature and media; it includes project information and a map viewer and provides a 

collaborative research space for the exchange of technical information on the effects of wind and 

marine renewable energy devices and their components.

 

24 https://www.ocean-energy-systems.org/oes-projects/task-4-assessment-of-environmental-effects-and-monitoringefforts-for-ocean-wave-tidal-and-current-energy-systems/ 25 http://tethys.pnnl.gov/ 
52 

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.

Appendix C: Key Contacts

Report Authors

Ian Baring-Gould

National Renewable Energy Laboratory

303-384-7021 

ian.baring-gould@nrel.gov

Sharon Kramer

H. T. Harvey & Associates

707-822-4141 

skramer@harveyecology.com

Corrie Christol

National Renewable Energy Laboratory 

303-384-7110 

corrie.christol@nrel.gov

Anna West

Kearns & West

415-391-7900 

awest@kearnswest.com

Al LiVecchi

National Renewable Energy Laboratory

303-384-7138 

al.livecchi@nrel.gov

Workshop Facilitation 

Ian Baring-Gould

National Renewable Energy Laboratory

303-384-7021 

ian.baring-gould@nrel.gov

Anna West

Kearns & West

415-391-7900 

awest@kearnswest.com

Sharon Kramer

H. T. Harvey & Associates

707-822-4141 

skramer@harveyecology.com

U.S. Department of Energy, Wind and Water Power Technologies 

Office 

Hoyt Battey

202-586-0143 

hoyt.battey@ee.doe.gov

Samantha Eaves

202-586-2112 

samantha.eaves@ee.doe.gov

Jocelyn Brown-Saracino

202-287-6097 

jocelyn.brown-saracino@ee.doe.gov

Alison LaBonte

202-287-1350 

alison.labonte@ee.doe.gov

Technical and Topical Expert Contacts

Physical Interactions with MHK Devices

Jocelyn Brown-Saracino

U.S. Department of Energy, Wind and Water Power Technologies Office 

202-287-6097 

jocelyn.brown-saracino@ee.doe.gov
53 

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.

Acoustic Output from MHK Devices 

Christopher Bassett

Woods Hole Oceanographic Institute (now with National Oceanic and Atmospheric 

Administration)

206-526-6435 

chris.bassett@noaa.gov 

Brian Polagye

University of Washington 

206-543-7544 

bpolagye@uw.edu 

Effects on Physical Environment 

Craig Jones 

Integral Consulting 

831-334-5466 

cjones@integralcorp.com

Jesse Roberts 

Sandia National Laboratories 

505-967-6974 

jdrober@sandia.gov

Effects of Electromagnetic Force from Tidal and Wave Systems 

Andrew Gill 

Cranfield University 

+44 7792 840151 

a.b.gill@cranfield.ac.uk 

Effects on Environmental Issues and Processes

Sharon Kramer 

H. T. Harvey & Associates

707-822-4141 

skramer@harveyecology.com 

Regulatory and Permitting

Anna West

Kearns & West

415-391-7900 

awest@kearnswest.com

Marine and Hydrokinetic Technology

Ian Baring-Gould

National Renewable Energy Laboratory

303-384-7021 

ian.baring-gould@nrel.gov

Robert Thresher

National Renewable Energy Laboratory 

303-384-6922 

robert.thresher@nrel.gov

Alison LaBonte

U.S. Department of Energy 

202-287-1350 

alison.labonte@ee.doe.gov
54 

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.

Appendix D: Organizational Participant List 

Organizations that participated in the 2015 MHK Workshop: 

• Cranfield University 

• Bureau of Ocean Energy Management (BOEM)

• Bureau of Safety and Environmental Enforcement (BSEE) 

• Federal Energy Regulatory Commission (FERC)

• H.T. Harvey & Associates

• Kearns & West

• Maine Department of Environmental Protection

• National Oceanic and Atmospheric Administration (NOAA) 

• National Renewable Energy Laboratory (NREL)

• Naval Facilities Engineering Command (NAVFAC)

• New West Technologies, LLC

• NOAA National Marine Fisheries Service (NMFS)

• Ocean Renewable Power Company (ORPC)

• Sandia National Laboratories (SNL)

• State of Maine Department of Marine Resources

• U.S. Coast Guard 

• U.S. Department of Energy (DOE) 

• U.S. Marine Corps 

• U.S. Navy

• Verdant Power Inc. 

• Woods Hole Oceanographic Institution (WHOI). 
55 

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.

Appendix E: Industry Input

Questions regarding the regulatory process posed by the MHK deployment community collected 

as part of an industry interview process completed by NREL staff prior to the workshop: 

• Describe your experience with deploying MHK device(s) in the water and collaborating 

with regulatory agencies. What has worked well? What has not worked well? What are 

key lessons learned to date? What opportunities exist to make these collaborative efforts 

more efficient and effective?

• Have any (perceived) risks been retired and, if so, is there widespread regulatory 

awareness of these? What key studies are still needed to retire key perceived risks?

• How are data generated by project developers viewed differently than data provided by 

third parties (industry contractors)? 

• What types of data and information have been transferable between sites? Between 

different projects at similar sites (e.g., nearby activities/structures)?

• What measurement protocols/best practices and technologies/sensors exist, and how is 

the acceptability of these being captured and shared within and between agencies? 

• Describe your experience with developing and implementing adaptive management 

approaches.