MT Magazine July 2013

marine technology

July 2013

Wave Energy Converters More than one approach

Enabling Advancement DOE’s water power program

Toward Commercialization The Verdant Power RITE project

RisingTIDE Getting a foot in the door with marine and hydrokinetic technologies

A publication of the Society of Naval Architects and Marine Engineers

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marine technology July 2013

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July 2013 marine technology

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(contents) marine technology July 2013

[features]

26

60

BY CMDR. ROB COHEN

BY NEIL NEROUTSOS, ARTHUR SEKI, AND STEPHEN LUCKETT

WEC Development and Commercialization How the United States Navy is approaching renewable ocean energy

32

Harnessing Tidal Velocity

BY DAVID AINSWORTH

The free-stream tidal energy market in the U.K. and Europe

20 Moving Water

BY JARLATH MCENTEE

How a tidal energy project off the coast of Maine is delivering power to the grid

40

Critical Role

The Utility Perspective The Snohomish County Public Utility District and tidal energy; and Hawaiian Electric and ocean renewable technologies

68

Validating the Wave Energy Model

BY THE ENGINEERING TEAM AT COLUMBIA POWER TECHNOLOGIES

Columbia Power’s development work with StingRAY [departments]

BY BILL STABY

Standards and certification in the marine renewable energy industry

44

From Demonstration to Market

76

BY DEAN R. CORREN

Evolving system moves toward commercial viability

marine technology

July 2013

Wave Energy Converters More than one approach

Enabling Advancement DOE’s water power program

Toward Commercialization The Verdant Power RITE project

RISINGTIDE Getting a foot in the door with marine and hydrokinetic technologies

A publication of the Society of Naval Architects and Marine Engineers

www.sname.org

ON THE COVER: Shown with its crossbeam and power trains raised for maintenance, Marine Current Turbines’ SeaGen free-stream tidal turbine was installed in Strangford Lough, which connects to the Irish Sea, in 2008.

SeaGen has served as a model for similar projects in the U.K. and Europe.

COVER DESIGN by BATES CREATIVE

52

Evaluate, Assess, Develop

BY MICHAEL C. REED

How the Department of Energy’s Water Power Program is enabling MHK technology advancement

87 4 From the Editorial Board 5 Feature Contributors 7 Industry Events 8 Policy Briefing 11 Marine Technology Notes 76 Education 79 In Review 82 Abstracts 85 Glossary 87 Historical Note

(mt) Marine Technology (ISSN 2153-4721) is published quarterly in January, April, July, and October by the Society of Naval Architects and Marine Engineers, 601 Pavonia Avenue, Jersey City, NJ 07306. Periodicals postage paid at Jersey City, NJ and additional mailing offices. Annual subscription rates: For U.S. and possessions, $125; single copy, $35. For international: $140; single copy, $35. Copyright © 2013 by the Society of Naval Architects and Marine Engineers.

POSTMASTER: Send address changes to the Society of Naval Architects and Marine Engineers, 601 Pavonia Avenue, Jersey City, NJ 07306.

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marine technology July 2013

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Š 2013 Siemens Product Lifecycle Management Software Inc. All rights reserved. Siemens and the Siemens logo are registered trademarks of Siemens AG. All other logos, trademarks or service marks used herein are the property of their respective owners.

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Answers for industry.

(from the editorial board)

marine technology July 2013

Waves, Tides, and Currents

E

agle-eyed readers of (mt) who follow such things will know that we originally had scheduled marine and hydrokinetic (MHK) technologies for the October 2013 issue. Then real life intervened in the form of schedules and workloads, which gave us the opportunity to move MHK up to this July issue. I’m actually really pleased by this; there’s a ton of innovative and exciting work being done in this space.

We set up this issue, in a way, with an introduction to the MHK sector in our October 2012 issue, an excellent piece authored by Cardinal Engineering’s Brian Lounsberry. Brian actually did too good a job on that one, as his was the first door we knocked on when we began planning this MHK issue. As we talked about the work being done with various MHK technologies, Brian suggested we talk with his colleague Whitney Blanchard, an engineer at Cardinal who provides support to the United States Department of Energy’s Wind and Water Power Technologies Office.

With her work focusing on technology development of MHK energy systems, Whitney is well versed in who’s doing what in this sector. She helped to connect us with device developers, designers, program managers, and other movers and shakers in the ocean renewable energy industry, and the result is the issue you hold in your hands. One of those key players was Jarlath McEntee at Ocean Renewable Power Company, who contributed an informative feature on his company’s tidal energy system, which was the first tidal energy project to deliver power to an electrical grid in North America. Another was Commander Rob Cohen, who checked in with a behind-the-scenes look at the work being done by the United States Navy on developing and testing wave energy converters.

We also have a detailed exploration of a free-stream tidal turbine, the SeaGen, installed on the coast of Northern Ireland in 2008 and now producing energy as the tides rush in and out of Strangford Lough. The success of SeaGen, in fact, is serving as a model for other tidal energy projects in the United Kingdom and in Europe.

There’s much more on MHK developments in this issue. Many thanks to Whitney Blanchard and to the team at Cardinal and the Wind and Water Power Technologies Office for their outstanding work.

And take a look at the box below to see what’s coming up in (mt). As you already know, topics are subject to change, but we’re developing some very relevant and thought-provoking content to share with you in upcoming issues. It’s going to be a great ride.

Douglas R. Kelly Editor

Coming in (mt) magazine I n the October 2013 issue, marine risk assessment will be front and center: how designers, operators, and other decision makers plan for risk, respond to risk, and lead through risk And in our January 2014 issue, we’ll explore the Mediterranean maritime sector: shipbuilders, cruise and ferry ship operators, and other key players in Italy, Greece, Turkey, and beyond

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marine technology July 2013

Published by the Society of Naval Architects and Marine Engineers 601 Pavonia Avenue, Jersey City, NJ 07306 Phone: 201-798-4800 Fax: 201-798-4975 www.sname.org/sname/mt Peter G. Noble President pnoble@sname.org Erik W. Seither Executive Director eseither@sname.org Bruce S. Rosenblatt Treasurer Susan Evans Grove Publications Director sevans@sname.org Douglas R. Kelly Editor dkelly@sname.org Alan Rowen Book Review Editor arowen@sname.org Dave Weidner, Advertising Sales advertising@sname.org Tommie-Anne Faix, Publications Sales Associate tfaix@sname.org Editorial Advisory Board Matthew Tedesco, Chair Rod Allan Chris Cikanovich Chris Dlugokecki Vicki Dlugokecki Norbert Doerry Jay Edgar Peter Tang Jensen

Luca Letizia Kevin McSweeney Peter Noble Jeom Paik Erik Seither Rik van Hemmen Peter Wallace

Design Bates Creative, Silver Spring, MD Officers of the Society Peter G. Noble, President Erik W. Seither, Executive Director Bruce Rosenblatt, Treasurer Regional Vice Presidents 2013: Atlantic South: H. Paul Cojeen Central & Gulf: Joseph H. Comer, III International: John Kokarakis 2014: Pacific: William B. Hale Atlantic North: John Volc 2015: Atlantic South: Robert J. Gies Central & Gulf: Scott C. McClure International: Harilaos N. Psaraftis 2016: Pacific: Dan E. McGreer Atlantic: Timothy J. Keyser Publication in (mt) Marine Technology does not constitute an endorsement of any product or service referred to, nor does publication of an advertisement represent an endorsement by the Society of Naval Architects and Marine Engineers or the magazine. All articles represent the viewpoints of the authors and are not necessarily those of the Society of Naval Architects and Marine Engineers, or the magazine.

Subscriptions: (mt) Marine Technology is circulated to all members of the Society as a portion of their dues allocation. Non-member subscriptions are $125 annually for the U.S. and possessions; single copies are $35. For international non-members, subscriptions are $140 annually; single copies are $35. (mt) Marine Technology is dedicated to James Kennedy, 1867-1936, marine engineer and longtime member of the Society, in recognition and appreciation of his sincere and generous interest in furthering ship design, shipbuilding, ship operation, and related activities.

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(feature contributors)

David Ainsworth joined Marine Current Turbines (MCT) in November 2003. He is a chartered engineer with a bachelor of science degree in aeronautics and astronautics from the University of Southampton. Previously, he worked in the aerospace, defense, and the electrical power generation industries. He has a wide experience in multi-disciplined projects requiring technical, commercial, and environmental skills. He is responsible for the project development team at MCT, which has been responsible for obtaining the consents and the installation of the SeaGen turbine in Strangford Lough. The team is currently managing the business and site development

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activities in Wales, Northern Ireland, and Scotland.

Commander Rob Cohen is the Naval Facilities Engineering Command Headquarters’ (NAVFAC) Energy Action Officer and Wounded Warrior Program Manager. Previously, he served as a program manager for the Commander Navy Installations Command; a public works director for a naval weapons station; assistant resident officer in Chart of Construction for Naval Base San Diego; and a facility manager for the United States Atlantic Fleet’s Headquarters and supporting staff. Cohen is a veteran of Operation Iraqi Freedom and is a graduate of Texas

A&M University with bachelor of science degrees in construction science and civil engineering.

The Columbia Power core engineering team is based in Corvallis, Oregon and includes (clockwise from top of photo): Ken Rhinefrank (vice president of research and development); Erik Hammagren (research

July 2013 marine technology

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(feature contributors)

Feature Contributors continued and development engineer—mechanical); Al Schacher (senior research and development engineer—controls); Pukha Lenee-Bluhm (senior research and development engineer—numerical analysis and control Optimization) ; and Joe Prudell (senior research and development engineer—electrical). The company was founded in 2005 and this team has applied more than 27 manyears together towards the StingRAY solution since that time.

Dean R. Corren was born in New York City and received a bachelor of arts degree in philosophy from Middlebury College and a master of science in energy from New York University.

Corren is currently director of technology with Verdant Power, Inc., in New York. His previous employment experience includes research scientist, NYU Department of Applied Science, New York, NY; consulting, CEO, Workable Computers, Inc., South Burlington, VT; Vermont State Representative and Outreach Director, Office of Congressman Bernard Sanders, Vermont. Corren has received ten patents in kinetic hydropower and electronics.

Stephen Luckett is responsible for project management for renewable energy research, demonstration, and development initiatives in the renewable technologies division at Hawaiian Electric. His responsibilities include managing relations with the Electric Power Research Institute, Hawaiian Electric’s Sun Power for Schools program, and the Public Utilities Commission. He also manages federal reporting on renewable energy projects and portfolios and leads company research into renewable and electropower technologies. Luckett holds a bachelor of science degree in marine engineering from California Maritime

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marine technology July 2013

Academy and pre-engineering studies at San Diego City College. He also holds a United States Coast Guard Third Assistant Engineer License.

Jarlath McEntee , ORPC’s vice president of engineering and chief technology officer, is a specialist in dynamics, thermodynamics, and fluid mechanics, and he drives the development of ORPC’s proprietary hydrokinetic energy technology.

He earned his bachelor of science degree in engineering at University College in Dublin, Ireland in 1986, and his master of science at Dartmouth College in 1989. He came to ORPC after spending more than 20 years in engineering and project management, having developed technical expertise in tidal power turbines; combined heat and power systems; Stirling engine and refrigeration systems; control system design and analysis; micro-mechanical structures; and marine engineering systems.

Neil Neroutsos has more than 20 years of experience in communications and marketing in the public and non-profit sectors. He serves as the chief spokesperson for Snohomish County Public Utility District, north of Seattle, WA. In that role, he has handled a broad range of issues, from green energy and conservation to emergency response and corporate corruption in the energy market. He has researched and written about a broad range of subjects, including water, energy, science, and technology.

Michael C. Reed serves as the

program manager and chief engineer for the United States Department of Energy’s Water Power Program, within the Wind and Water Power Technologies Office. He is responsible for managing the department’s research, development, test,

and evaluation efforts for both marine and hydrokinetic, and hydropower technologies. He holds a bachelor of science degree in marine engineering from the United States Merchant Marine Academy and master of science degree in environmental science from Johns Hopkins University.

In his previous roles with the United States Navy and engineering consulting firms, he focused on the development of advanced marine power and propulsion systems.

Arthur Seki has 36 years of expe-

rience in renewable energy, including 14 years at the University of Hawaii’s Hawaii Natural Energy Institute and 22 years at Hawaiian Electric. He has conducted research, development, and demonstration projects related to biomass; geothermal; solar; wind; hydroelectric; ocean energy; hydrogen; and fuel cells. As director of renewable technology, Seki continues to monitor renewable energy projects; evaluate, assess, or participate in studies related to renewable resources and technologies; and develop and install renewable demonstration projects. He holds a master of science degree in civil engineering from the University of Hawaii and a bachelor of science in chemical engineering from Arizona State University.

Bill Staby is founder and CEO of Boston-based Resolute Marine Energy, Inc. which, since 2007, has been developing technologies that harvest energy from ocean waves. He is chairman of the United States delegation to IEC TC-114 and a U.S. representative to the IEC Conformity Assessment Board Working Group 15. He is an active member of the Ocean Renewable Energy Coalition and a member of the Technical Advisory Board of the University of North Carolina-Coastal Studies Institute. Staby earned his master of business administration degree from New York University in 1988. www.sname.org/sname/mt

(industry events)

Upcoming Events: July, August, and September JULY 2013 Navy League Special Topic Breakfast #5 July 2 Ritz Carlton Pentagon City Arlington, VA

ASME/USCG Workshop on Marine Technology and Standards July 24-25 Double Tree Hotel Arlington, VA

Navy League Navy IPO Industry Day #3 August 21 Navy League Building Arlington, VA

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Contact: kpagoni@navyleague.org

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Engine As A Weapon V (EAAW) International Symposium July 16-17 Bristol, Great Britain Contact: conferences@imarest.org

Navy League Navy IPO International Day July 17 Navy League Building Arlington, VA Contact: kpagoni@navyleague.org

AUGUST 2013 4 Day Basic Dry Dock Training Courses August 5-8 Boston, MA

Fleet Maintenance & Modernization Symposium 2013 August 27-28 Town and Country Resort & Convention Center San Diego, CA Contact: mhuling@navalengineers.org

Navy League Special Topic Breakfast #6 September 19 Location TBD Contact: kpagoni@navyleague.org

4th IMarEST Condition Based Maintenance Conference September 25-26 London, Great Britain Contact: events@imarest.org

NOVEMBER 2013

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1st IMarEST Offshore Oil & Gas Engineering Conference August 21-22 Houston, TX Contact: events@imarest.org

SEPTEMBER 2013 Contract Management for Ship Construction, Repair, & Design September 10-12 London, Great Britain

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July 2013 marine technology

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(policy briefing)

MHK Siting and Permitting Working toward commercialization with federal and state agencies

By Cherise Oram and Chad Marriott

M

arine and hydrokinetic (MHK) energy projects have the potential to produce significant amounts of clean and renewable power for the United States. However, placing new technologies in relatively unstudied environments, such as the ocean, presents a challenge to permitting agencies and developers who are striving to get the industry off the ground in an environmentally responsible manner. Wave and tidal energy projects, in particular, face challenges not raised by conventional hydropower and new in-river technologies that are subject to the same licensing and permitting regime. With that backdrop, it may be easy to understand why the nascent MHK industry is focused on regulatory challenges and the need for proportional, adaptive permitting processes that will enable the industry to grow in a phased, iterative manner toward commercialization.

The diversity of stakeholder groups with an interest in MHK projects cannot be underestimated, and their diverse interests often drive how and where projects are proposed. Siting and permitting involves federal and state agencies with jurisdiction over energy development; water quality and in-water discharges; the sea bed; coastal resources and marine sanctuaries; cultural resources; shipping and navigation; crabbing and fishing; endangered and threatened species; marine mammals; migratory birds and seabirds; recreation; public safety; and other issues. In addition, tribes, commercial and recreational fishers, surfers, and nonprofit environmental organizations all have a seat at the table.

The licensing and permitting process—which is overseen by the Federal Energy Regulatory Commission (FERC)—has the capacity to encompass virtually everything that lives in, depends on, enjoys, or is a natural characteristic of the ocean or coastal environment.

Licensing process In the initial stages of project investigation, feasibility assessment, and environmental evaluation, developers may start the licensing process by applying for a preliminary permit with FERC. Such an application creates open competition among would-be developers for a site, with the winner awarded site priority for up to three years. FERC has issued such preliminary permits to wave, ocean current, tidal current, and in-river current (8)

marine technology July 2013

technologies. The preliminary permit is a valuable tool because it enables developers to test the waters, so to speak, in a particular region, community, and resource area. By the end of the permit’s term, the developer will typically either decide to submit a license application to develop a project at the site or to abandon that particular location.

MHK projects that will be connected to the electric grid must be licensed by FERC, whose extensive licensing regime sets the framework for obtaining all other state, tribal, and federal environmental approvals and for vetting the comments and recommendations of other stakeholders and the public. In addition, developers must separately obtain rights to use the submerged or submersible land in their project areas. MHK projects on the outer continental shelf (OCS)—located beyond three or nine nautical miles from shore depending on the state—must obtain leases from the Department of Interior’s Bureau of Ocean Energy Management, while MHK projects on the seabed landward of the OCS and in-stream hydrokinetic projects must secure state lease rights. The entire licensing and associated permitting process can take three to five years for a commercial, grid-connected project.

A developer may forgo FERC licensing only if it fulfills two requirements: that it is testing an experimental technology for a short period of time for the purpose of conducting studies, and any power generated from the test facility is not connected to the interstate electric grid. Such test projects must still obtain other federal and state approvals, however, such as discharge permits and water quality certifications under the Clean Water Act (CWA) and approvals under the Endangered Species Act (ESA) and Marine Mammal Protection Act (MMPA), as appropriate.

In 2007, FERC announced a pilot project policy intended to reduce regulatory barriers to hydrokinetic demonstration projects. Pilot project licenses are available for projects that are 5 MW or less; are removable or able to be shut down on relatively short notice; are not located in waters with “sensitive designations”; and are for the purpose of testing new technologies or determining appropriate project sites. Pilot project licenses will generally be issued for short terms, such as five years, thus requiring the licensee to either apply for a standard www.sname.org/sname/mt

(30- to 50-year) license or decommission the site at the end of the pilot project term. FERC has suggested that it should be able to issue pilot project licenses in six months compared to five or more years for traditional licenses.

However, challenges with obtaining other permitting approvals will continue to require more time as applicants endeavor to obtain approvals under the CWA, ESA, MMPA, and the Coastal Zone Management Act.

Adaptive management Given the sheer number of regulatory and stakeholder interests represented in the licensing and permitting processes for MHK projects, developers should begin stakeholder consultation as early as possible. To avoid

-Jack Fisher, President

protracted permitting and potential disagreements in the licensing proceeding, developers and stakeholders may strive to agree on appropriate conservation measures, monitoring, and decision-making triggers that the developer will undertake to meet its various regulatory requirements. In addition, an adaptive management approach—using developing information to inform and guide ongoing siting and operational decisions—can be an important tool for developers, agencies and other stakeholders to address any remaining uncertainties associated with the project technology and its interaction with existing uses or environmental resources.

Once these technologies are deployed and studied in larger numbers and their effects monitored,

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July 2013 marine technology

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(policy briefing)

The diversity of stakeholder groups with an interest in MHK projects cannot be underestimated, and their diverse interests often drive how and where projects are proposed.

MHK Siting and Permitting continued however, licensing and permitting participants should focus on specific conservation measures rather than open-ended, adaptive provisions. As we all gain more certainty regarding the presumed lack of significant project effects, developers should reap the benefits of developing that information by winning longer licenses with clear and measurable conditions.

Coastal and marine spatial planning Primarily a concern for offshore projects and not instream hydrokinetics, coastal and marine spatial planning (CMSP) is a relatively new and important issue that is already impacting project development.

Recently, the National Ocean Council, consisting of representatives from 27 federal agencies and departments, published its long-awaited plan for implementing President Obama’s National Ocean Policy. This implementation plan is intended to improve interagency collaboration and prioritization in a broad range of policy areas affecting ocean uses including commercial fishing, commercial shipping and ports, military activities, aquaculture, and conventional and renewable energy development.

The plan does not create or supersede existing law, but instead describes steps that federal agencies will take to coordinate with tribes, state and local governments, marine industries, and other stakeholders with the goal of streamlining ocean and coastal management efforts. More specifically with regard to ocean economy, the plan states that one desired outcome is to “provide greater accessibility to data and information to support commercial markets and industries,” including offshore energy, by doing things such as expanding an integrated geospatial database on public and private ocean data.

In addition, the Departments of Energy, Commerce, and the Interior will collaborate with the National Science Foundation to compile and make available data on climate, water, wind, and weather as well as on wave and tidal energy resources.

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In addition to this federal effort, several states, including Washington, Rhode Island, Massachusetts, and Oregon, have pursued CMSP to help determine the most appropriate uses for areas in the states’ territorial seas. These plans vary, but have many things in common. For example, each examines or proposes to examine existing and proposed ocean uses and articulates policies regarding the acceptable locations and uses of ocean-based energy generation facilities. It will be critical for MHK developers to engage in these processes on state-by-state and regional bases to ensure that such policies are properly scoped to allow, or even facilitate responsible development of, MHK technologies in appropriate locations.

Many components of the regulatory framework governing MHK projects are still developing. It will be important for industry stakeholders to provide input about their needs through the various public processes to help policy makers understand that MHK projects are still relatively small in size and likely impact. As developers, agencies and other stakeholders continue to learn about these technologies and their interaction with existing uses and the environment, licensing and permitting processes should change and flex in response to new information. To some extent, this is already happening. However, until we gain more certainty, regulatory requirements should not overburden the industry. Rather, federal and state agencies should continue to work with industry stakeholders to ensure that licensing and permitting requirements are proportional to anticipated impacts and encourage the responsible, phased development of this important new industry. MT Note: This article is for informational purposes only and should not be treated as legal advice. Specific questions about this area should be discussed with a qualified attorney.

Cherise Oram is a partner in Stoel Rives LLP’s environmental and natural resources practice group where she advises energy project developers on federal natural resources law. Chad Marriott is an attorney in Stoel Rives LLP’s energy development team. www.sname.org/sname/mt

(mt notes)

The first testing of iMEC-enabled hardware in uncontrolled conditions was done at Lake Washington. The PTOs were deployed in January 2013 following intensive testing on a hydraulic test stand.

Harnessing Magnetostriction The next generation wave energy converter?

By Balakrishnan Nair and Rahul Shendure

www.sname.org/sname/mt

W

ave energy has the potential to meet nearly 10% of global electricity demand (approximately 2,000 TWh/year). Unlike wind or solar energy, wave energy can be forecasted several days in advance and is located close to coastal areas with growing demand. Inventors and organizations around the world have tried to turn this low-frequency, low-amplitude resource into utility-scale electricity for decades. These attempts have universally used power generation technologies with moving parts, resulting in high operating and maintenance costs, as well as low efficiency and the need for large amounts of structural mass, which together drive up capital cost.

The levelized cost of energy (LCOE) for wave energy has been estimated to be between 25 and 60 cents/kWh, many times higher than that from conventional sources.

At Oscilla Power, Inc. (OPI), we are developing a patented magnetostrictive wave energy harvester (MWEH) that could enable the disruptively low-cost production of grid-scale electricity from ocean waves. Designed to operate cost effectively across a wide range of wave conditions, the MWEH will be the first use of reverse magnetostriction, a phenomena in which high-magnitude, but low-displacement, mechanical load changes are converted into magnetic flux changes and then electricity (via induction), for large-scale energy production.

While the newly-developed, higher-performing magnetostrictive alloys (such as iron-gallium) are

prohibitively expensive for utility-scale power generation applications, iron-aluminum (Fe-Al) alloys can provide the required cost and capacity.

Our iMEC technology platform enables Fe-Al alloys to provide the required performance for power generation. The driving magnetomotive force is provided by permanent magnets, which typically make up less than 1% of the generator mass.

Tension changes on this circuit result in changes in magnetic permeability of the Fe-Al rods, resulting in changes in flux density within the circuit—all with no perceptible relative motion (less than 200 ppm of deformation). Electricity is generated by electromagnetic induction, using copper coils wound around the alloy rods.

The pre-compressed rods never go out of compression during normal operation. During extreme conditions that result in very high tension, safety bolts are engaged that pick up the excess mechanical load. These features are intended to eliminate fatigue-related failures.

Magnetostrictive harvesters have been shown to have greater than 80% mechanical to electrical efficiency, a capability that should enable us to achieve higher efficiencies than have previously been demonstrated for wave energy converters (WEC).

Tension leg platform model The MWEH’s architecture is similar to that of tension leg platforms used in the oil and gas industry. It consists July 2013 marine technology

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(mt notes)

The MWEH can produce energy from waves with no significant relative motion between or significant dimensional change of its components.

Harnessing Magnetostriction continued of a partially submerged buoy, anchored to a catenarymoored heave plate by taut tethers. These tethers are largely made up of, or are connected to, discrete, robust power takeoff modules (PTOs), which contain iMECenabled generators. Hydrodynamic forces on the buoy cause the line tension of each tether to continuously change, resulting in a high-force, low-displacement mechanical energy input that is converted to electrical energy in the PTOs. The MWEH has several advantages over other approaches to wave energy generation, giving it the potential to achieve the following.

No moving parts. The MWEH can produce energy from waves with no significant relative motion between or significant dimensional change of its components.

This eliminates sub-system (for example, lubrication, bearings, and seals for moving components) costs and

will significantly reduce operating and maintenance costs due to the elimination of the need to periodically service or replace components such as joints or bearings.

Low cost materials. The MWEH’s materials set does not include significant quantities of any supply-limited or expensive materials. While small quantities of commercial rare earth magnets are used, these could be replaced by ferrite magnets if their cost or availability becomes an issue.

Low cost manufacturing. All components used in the MWEH’s PTO are amenable to low-cost, high-volume, automotive-scale manufacturing. The buoys and anchors have no complex parts.

Relative ease of deployment. Standard vessels that do not have to be customized to hold equipment in a specific direction or to deploy devices onto the ocean floor can be used.

High efficiency across the wave spectrum. Operating substantially below the resonant frequency, the MWEH does not experience steep reductions in efficiency on either side of a nominal/rated condition, as is the case with many other WEC technologies that rely on wave motion to move a floating body. While such WEC systems are intrinsically “narrow-band” technologies, the MWEH operates as a wide-band device across the wave spectrum.

Minimal environmental impact. Broadly speaking, the MWEH’s impacts should be more manageable than that of other approaches for the following reasons: at least 8 m between individual tethers; EMF leakage below detection limits for marine organisms; anchor design flexibility; customizable above-water buoy profile to minimize its attraction to sea life; and minimal noise due to lack of moving parts.

Technology development

Conceptual illustration of OPI’s magnetic circuit.

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Development of our technology has proceeded along three general thrusts: generator design and optimization, including validation and improvement of our performance model; design and optimization of the PTO and overall system, including the buoy and anchor; and www.sname.org/sname/mt

The architecture of the MWEH is similar to that of tension leg platforms used in the oil and gas industry, consisting of a partially submerged buoy anchored to a catenary-moored heave plate by taut tethers.

deployment of sub-scale systems in wave tanks and open-water environments.

Generator design and optimization. Our key accomplishments in this area include:

testing, a variety of sealing methodologies that have been proven in analogous systems.

At the system level, our work has focused on the modeling and simulation of a utility-scale system in central Oregon coast wave conditions. Executed in Orcaflex by naval engineering consultancy Marine Innovation and Technology, these simulations output a time series of tether tensions.

When combined with the generator performance model, these outputs can predict power generation as a function of wave conditions and system design. The simulations enabled us to design a system that can survive a 100-year wave.

We worked with Powertech Labs, a subsidiary of Canadian utility BC Hydro, to develop conceptual designs for the power electronics and transmission components of

the MWEH system using off-the-shelf hardware. We also have carried out exhaustive design failure modes and effects analysis with external experts to prioritize technical risks associated with the MWEH. Deployment of sub-scale systems. In 2010, we conducted two rounds of wave tank testing at the University of California at Berkeley’s tow tank. In addition to accomplishing preliminary reduction to practice, we were able to demonstrate high correlation between the predicted and actual generator output.

In 2012, Professor Jim Thomson and his team at the Applied Physics Laboratory at the University of Washington designed a mooring system that enabled us to conduct the first testing of iMEC-enabled hardware in uncontrolled conditions at Lake Washington. The

• Performance: production of more than one tesla of magnetic flux density change, a level of performance sufficient to achieve the power density and energy generation assumed in our cost model • Scale up: Core size was successfully scaled up from approximately 2.5 cm to more than 10 cm. To date, the generator testing has validated the accuracy of our predictive models for achievable flux change and power production • Reliability: Magnetostrictive generators have been successfully subjected to more than 1.5 million load cycles (approximately 2.4% of the number of cycles expected over a 20-year lifetime).

Following an initial decrease of approximately 2.5%, which can be attributed to core and coil heating, power production remained constant.

Design and optimization of the PTO and overall system. We have executed design, prototype testing, and modeling activities to optimize the PTO and overall system. Finite element design engineering was used to maximize load transfer from the tethers to the magnetostrictive generator and to evaluate, along with prototype www.sname.org/sname/mt

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(mt notes)

Harnessing Magnetostriction continued The MWEH generator testing has validated the accuracy of OPI’s predictive models for achievable flux change and power production.

will be tested at Isle of Shoals in New Hampshire, together with the University of New Hampshire’s Center for Ocean Renewable Energy, in 2013-2014.

Detailed cost modeling suggests that a utility-scale MWEH array using gen 3 generators, located off the central Oregon coast, could produce electricity at less than 10 cents/kWh without incentives and without requiring significant learning curves.

We would like to acknowledge the contributions of Professor Jim Thomson and his team at the Applied Physics Laboratory at the University of Washington to the Lake Washington deployment.

We also would like to acknowledge the following individuals for their contributions to our progress over the past three years: Alison Flatau (University of Maryland); Dominique Roddier and Antoine Peiffer (Marine Innovation and Technology); Joao Cruz and the Wave Energy team at GL Garrad Hassan; Dallas Meggitt (Sound and Sea Technology); and Jahangir Khan (Powertech Labs). MT Balakrishnan Nair is president and CTO of Oscilla Power, Inc. Rahul Shendure is CEO of Oscilla Power, Inc.

LEARN MORE PTOs were deployed in January 2013 following intensive testing on a hydraulic test stand.

During the 3-month deployment, 20 wave events were recorded. Detailed analysis of the hourly average tether load change rate was conducted for the data from a particular storm to validate the dependence on wave height. We also were able to validate a strong correlation between predicted output of the PTOs, calculated using the tether loading, and their actual output. Finally, we validated that power was harnessed across all of the wave frequencies present.

For further information on wave energy or magnetostriction, check out the following resources.

Future plans

“A Review of Magnetostrictive Iron–Gallium Alloys,”

by J. Atulasimha and A.B. Flatau, Smart Materials and Structures (2011)

As the MWEH has moved from the lab to tank to open water, the technology has performed successfully, with a strong correlation between predicted and actual output.

Our ongoing and future technology development activities include generator scale-up, additional prototype deployment, and integration of component technologies to drive additional cost reduction. Prototype systems with (14) marine technology July 2013

“A Brief Review of Wave Energy,” by T.W. Thorpe, ETSU-R120, AEA Technology for the UK Department of Trade and Industry (1999) “The Future Potential of Wave Power in the United States,” by M. Previsic, RE Vision Consulting for the U.S. Department of Energy (2012)

“Application of the Villari Effect to Electric Power Harvesting,” by X. Zhao and D.G. Lord, Journal Of Applied Physics (2006)

www.sname.org/sname/mt

(mt notes)

Wavebob physical models at MARIN with mesh and structural model used in WaveDyn.

Developing Design Tools How essential performance and loading calculations are enabled for MHK devices

By Jarett Goldsmith

www.sname.org/sname/mt

A

pproximately 71 percent of the earth’s surface is covered by oceans and, throughout human history, societies have used their bountiful resources. The majority of the world’s population lives within a few hundred miles of a coastline, and there is huge demand for electricity to power modern lifestyles.

Marine and hydrokinetic (MHK) energy developers have realized the tremendous opportunity that oceans present for the sustainable conversion of their energetic motions—in the form of ocean surface waves and marine currents—into clean electricity. This is no trivial task, and the design challenges faced by the emerging wave and tidal energy sectors are many. Successful development of such technologies will rely on the use of dependable design tools that have been specifically developed to meet those challenges.

Numerical design tools can reliably simulate the power performance and loading that the devices are expected to experience during their operational lifetimes. This type of tool is invaluable for • e nabling an improved understanding of t he technologies • reducing risk and costs in prototype development and

progression of technology readiness • pursuit of optimized design at large scale • provision of inputs for array design and levelized cost of energy (LCOE) assessments • compliance with certification rules and standards.

When a technology developer/owner seeks certification of their MHK device, whether prototype certification for a single device or type certification for a mass-produced product, they will have to provide documentation to an accredited certification body for review. A critical element of the certification process is the design assessment, and documentation must be provided describing the loads and response of all major components of the device as part of that process.

The necessary design load cases for consideration are described in standards and guidelines such as those being developed by the International Electrotechnical Commission and various certification bodies such as Det Norske Veritas and Germanischer Lloyd.

Wave energy converters (WECs) and ocean current turbines are complex systems operating in constantly changing environments. Effective design tools must accurately model the current/wave environment; incorporate July 2013 marine technology

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(mt notes)

Developing Design Tools continued and WaveDyn for the design of ocean current turbines and WECs, respectively.

Tidal Bladed’s graphical user interface.

Fundamentally similar

rigorous mathematical models that can represent the nonlinearities in loading and response; and integrate hydrodynamics, structural dynamics, and the response of power takeoff (PTO) and control systems in a fully-coupled manner. While high-fidelity computational fluid dynamics simulations like Reynolds Averaged Navier Stokes models can capture most of the hydrodynamic physics involved, such models are computationally intensive and typically do not include all system and subsystem loads. Such a computationally demanding and decoupled approach is not suitable for loads calculations. Standard loads reports for the wind and MHK industries typically require running thousands of time domain simulations for a given device design. Therefore, besides accurately representing all relevant loading, design tools must be rapid and user friendly so that engineers who may not be experts in hydrodynamic codes can run them effectively on standard office computers.

Of course, validation of design tools is essential in an engineering environment where device safety, performance estimates, and economic investment are dependent on the use of trusted analysis methods.

Unlike most offshore structures, MHK systems are designed to respond actively to waves and currents, rather than to simply survive them, and almost all concepts incorporate subsystems that are required to operate in a new and uncertain marine environment. As such, extensive numerical model verification and validation must occur for designers to establish trust that new MHK-specific design tools produce reliable results.

Our wave and tidal energy engineers and software developers at GL Garrad Hassan (GL GH) have built upon the company’s experience developing engineering models over nearly three decades. We have developed a design tool for wind turbines, Bladed, to produce the integrated software packages Tidal Bladed (16) marine technology July 2013

Ocean current turbines are often described as underwater wind turbines, and indeed a significant percentage of today’s leading design concepts use horizontal-axis rotors in systems that are fundamentally quite similar to the modern wind turbine. In the same way flowing air drives wind turbines, so does flowing seawater drive ocean current turbines.

Much of what has been learned and developed for the wind industry can be adapted for application with current turbines. However, ocean current turbines require other specific considerations including wave/ current kinematics; flow turbulence; hydrodynamic inertia effects; buoyancy forces on the rotor/structure; and cavitation inception. These effects can be significant for turbines operating in marine currents, so Tidal Bladed was adapted from the aero-elastic package for wind turbine design, Bladed, to include them.

Turbines placed in marine currents may be exposed to off-axis flow, flow shear, and considerable turbulence.

Therefore, models for dynamic inflow and dynamic stall, as well as hydrodynamic inertia effects on the rotor and support structure, must be included to fully represent the device behavior. Additionally, the loading and behavior during faults and controller events can be significant for these electricity generating machines. Tidal Bladed incorporates such models with a blade element momentum code and enables time-domain simulation of combined current, wave, and wind loading with closed-loop turbine control, full hydro-elastic modeling and seismic excitation, and a range of supporting steady-state calculations.

Tidal Bladed’s multi-body, multi-physics calculation code includes various modules covering dynamic load simulations; analysis of loads and energy capture; batch processing; automated report generation; interaction with the electrical network; and model linearization for control design. The flexible, multi-body formulation of structural dynamics enables deflections caused by hydrodynamic loading and other loading effects to be fed back, updating the location and relative motion between the flow, the blades, and the structure. Additional modules enable the moorings of floating tidal systems to be modeled as well as those systems with multiple rotors.

Besides the focus on incorporating rigorous numerical models, a lot of effort has been put into the validation of Tidal Bladed. Before its development, the design tool on which it was based, Bladed, had already been validated during its 20 years of use in the wind industry. Currently, ten of the world’s leading tidal turbine developers hold www.sname.org/sname/mt

WaveDyn’s graphical user interface.

Tidal Bladed licenses and many of them have conducted their own validation studies in addition to the work that we have carried out. We also are participating in the Reliable Data Acquisition Platform for Tidal project, commissioned and funded by the Energy Technologies Institute (ETI). As part of this project, GL GH will carry out validation of the environmental and hydrodynamic models employed within Tidal Bladed against data collected from sea trials of a 1 MW ocean current turbine deployed at the European Marine Energy Centre. These results will be produced over the next year and will be published when completed.

Presently, commercial tidal stream turbine developers are using the tool to support progression of their designs in various ways. For example, Kawasaki Heavy Industries (KHI) use it as an integral design tool as they evaluate power performance and calculate the lifetime fatigue and ultimate design loads for components ranging from the blades through to the drive train and support structure. Time domain simulations have also proved vital for the design of their closed-loop power production controller and the supervisory control system to be used in the KHI turbine.

WaveDyn Unlike wind turbines, and to some extent ocean current turbines, WECs have not converged on a single dominant form. Systems being developed range from those consisting of singular, constrained buoys to those with multiple interconnected and wave-activated components. Meanwhile, PTO systems—hydraulic, pneumatic, direct-drive, and piezoelectric—using components from a wide range of www.sname.org/sname/mt

Invest in Yourself

Increase Your Knowledge Base United States Merchant Marine Academy

Master of Science – Marine Engineering

Online Based, Distance-Learning Engineering Education A blend of application and theory at the graduate level focused on advanced concepts in Marine Engineering.

This 36-credit program is designed for working professionals and can be completed without the need to take a leave of absence from a job or relocate. It consists of seven required courses and five electives. A suitable thesis or design project may be substituted for one or two electives. For additional information visit our website: www.usmma.edu/after-graduation/graduate-program July 2013 marine technology

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(mt notes)

Developing Design Tools continued industrial applications have all been proposed. Therefore, in addition to a focus on accuracy and user friendliness in common with Tidal Bladed, the development of WaveDyn also focused on flexibility and the ability to model a wide range of structures and WEC types.

WaveDyn uses a flexible, multi-body calculation code for use in time domain performance and loading simulations for single machines and small WEC arrays.

The multi-body formulation enables a WEC simulation model to be built up by joining any number of self-contained bodies, each with a range of physical properties.

The bodies that are linked together can have structural, hydrodynamic, PTO, and moorings components. All of the applicable loads and dynamic response of the system are then coupled in the time domain solver to produce the simulation results. A variable time step, adaptive order algorithm is employed by the solver, so that WaveDyn adjusts to the complexity of the built-up model. The active adjustment to the speed of the system dynamics facilitates rapid, desktop PC simulation times without compromising the accuracy of results.

It also was important that the tool enabled a wide range of wave conditions as input, from measured sea states to parameterized spectral shapes (including directional spectra). The current version of the tool can incorporate nonlinear hydrostatic loads and first-order hydrodynamic loads (diffraction and radiation forces) by processing data output from an external potential flow solver. As such, at this stage of its development, the tool is primarily valid for simulation of WEC performance and operational loading, as the models may break down in extreme seas where the assumptions behind linear hydrodynamics may no longer hold.

Commercial work undertaken by GL GH with specific technology developers, such as Columbia Power Technologies Inc. in the United States and AW-Energy Oy in Finland, has provided validation data sets that cover very different machine types and subsystems. We also are leading the Performance Assessment of Wave and Tidal Array Systems (PerAWaT) project commissioned and funded by the ETI. This provided large-scale tank testing of high-precision physical models for two distinctly different WEC concepts—Wavebob and Pelamis, in collaboration with Wavebob Ltd. and Pelamis Wave Power Ltd., as well as comparisons with high-fidelity, fully non-linear hydrodynamic models.

The simulation of large-scale (approximately 1:20), high-specification, experimental models of the (18) marine technology July 2013

commercial WEC developed by Wavebob Ltd. demonstrates how the design tool can be used to support technology development. The Wavebob models were tested in the seakeeping and manoeuvring basin at MARIN, in the Netherlands, which is one of the largest facilities of its type in the world. Tests with single models were conducted in November 2011, to gather data on the behavior of the device in isolation. To investigate the interactions between WECs operating in an array, subsequent tests were conducted in March 2012 with a group of four models. Infrared motion capture equipment was used to track the motions of the WEC(s) in six degrees of freedom. The PTO joints contained computer-controlled servo motors in order to faithfully represent the properties of the proposed full-scale design. Tests were carried out in a range of wave conditions, from sinusoidal regular waves through to irregular, directionally spread waves that were representative of realistic sea conditions. This testing resulted in a comprehensive data set that could be compared to the numerical models developed with WaveDyn, validating the accuracy of the simulations for use in design development.

Moving forward A primary goal behind the development of these tools was to establish a standard platform for the design of MHK technologies. Their development has significantly advanced the understanding of individual device loading and performance, and is also feeding in to an understanding of the interactions between devices that will be crucial for planning commercial-scale arrays of WECs and marine current turbines. Future tools being developed under the ETI commissioned and funded PerAWaT project, WaveFarmer and TidalFarmer, build upon this knowledge to provide wave and tidal farm planning and array performance calculation tools.

Meanwhile, developing fully-coupled design tools sophisticated enough to simulate all of the applicable loads on MHK systems, while capturing the physics of the systems correctly, and still enabling those simulations to be run rapidly on desktop PCs, is an ongoing process.

Further validation and improvement is being pursued, and as more full-scale prototypes are tested in relevant ocean conditions, the design tools that helped enable the deployment of those prototypes also will benefit. MT Jarett Goldsmith is an engineer and project manager in wave and tidal energy at GL Garrad Hassan. www.sname.org/sname/mt

Bellevue, WA

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November 6-8

l Hyatt Regency Bellevue

The SNAME Annual Meeting is the only industry event that includes all the diverse technical interests and professional specialties in naval architecture, marine and ocean engineering and related disciplines.

DON’T MISS: 40+ Hours of Technical Programming, including: - SNAME Annual Meeting Papers - NSRP Ship Production Symposium (SPS) Papers - Technical & Research (T&R) Sessions - Special Panels Student Program Expo of the Latest Technologies Continuing Education Courses Alumni Events Pre-Annual Meeting External Training Courses Innovation Sessions Networking Events Offsite Events: - 6th Annual Golf Tournament - 5th SNAME Cup Sailing Regatta - Footy Yacht Regatta Design & Competition

For more information: Visit : www.sname.org Annual Meeting: alana@sname.org Expo: howard@marinelink.com

How a tidal energy project off the coast of Maine is delivering power to the grid

By Jarlath McEntee

O

cean Renewable Power Company (ORPC) is a global leader in marine hydrokinetic power systems and projects. Our technolog y generates clean, predictable, renewable grid-compatible power from oceans and rivers without using dams or other barriers. Headquartered in Portland, Maine, we develop and license projects at tidal energy sites at the Bay of Fundy (both in the United States and Canada), and at Cook Inlet, Alaska. These projects have the potential to generate more than 300 MW of electricity, enough to power roughly a quarter of a million homes.

In 2012, we installed and started operation of the Cobscook Bay Tidal Energy Project, the first commercial, (20) marine technology July 2013

grid-connected hydrokinetic tidal energy project in North America. Located at the mouth of the Bay of Fundy near Eastport and Lubec, Maine, this is the only ocean energy project, other than one using a dam, that delivers power to a utility grid anywhere in the Americas.

The project has received a Federal Energy Regulatory Commission (FERC) pilot project license and the first Maine Department of Environmental Protection General Permit issued for a tidal energy project. We also have received approval for the first power purchase agreement (PPA) for tidal energy from the Maine Public Utilities Commission, and we have executed a 20-year PPA with Bangor Hydro Electric Company, the grid operator in eastern Maine. www.sname.org/sname/mt

ORPC also performs environmental data gathering, monitoring, and analysis for such projects, and collaborates with communities, agencies, non-governmental organizations, elected officials, fishermen, and other harbor users.

Power system We have developed three models of our power system for commercial deployment: the TidGen Power System for tidal and deep river sites, which has a rated capacity of 150 kW; the OCGen Power System for deep-water ocean sites; and the RivGen Power System for river sites, particularly those serving isolated communities.

Our turbine generator unit (TGU) is the core component or “engine� of all three systems. The TGU uses advanced design cross-flow (ADCF) turbines to drive a permanent magnet generator mounted between the turbines on a common driveshaft. The turbines rotate in the same direction irrespective of the tidal flow direction. The rotational speed of the turbines is directly related to the water flow speed.

The ADCF turbines are directly coupled to an underwater direct-drive permanent magnet generator, which produces variable frequency, variable voltage 3-phase alternating current (AC) power with a www.sname.org/sname/mt

normal rotational speed of 0 to 32 revolutions per minute (RPM) depending on the tidal velocity. Because of the direct coupling, no gears are needed or used.

The TidGen Power System TGU is 98 ft. in length, 17 ft. high, and 17 ft. wide. It is attached to a bottom support frame, which holds the TGU in place approximately 15 ft. above the sea floor. The bottom support frame is constructed of steel and the TGU is constructed of steel and composite material. The coupled TGU and bottom support frame comprise the TidGen device. TidGen is connected to an underwater power consolidation module, which is then connected to an on-shore station through a single underwater power and data cable. The on-shore station is interconnected to the local power grid.

TidGen and the related cabling and on-shore station comprise a complete TidGen Power System.

August 2012: The TidGen TGU 001 being installed in the Cobscook Bay project using a heavy lift crane.

Turbine design Since 2009, we have conducted scale model testing of our cross-flow turbines with the University of Maine (UMaine) as part of a U.S. Department of Energy small business technology transfer (STTR) program. We combined knowledge from this effort with data gained from in-water deployments of prototype and beta power systems conducted in 2008 and 2010. The research and development partnership July 2013 marine technology

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Each ADCF turbine used in a TidGen device (there are four total) contains a set of four foils mounted into the TGU using spokes and a series of mounting frames. between ORPC and UMaine has created a comprehensive theoretical and practical program for cross-flow turbine engineering. The STTR research has led to a systematic experimental basis for the design of effective hydrokinetic turbines for use in open, unducted flows and enables the use of experimental information to improve efficiency and performance of cross-flow turbines.

UMaine researchers have designed and built turbine test apparatus and instrumentation using a 1/10 scale model. Using this equipment, ORPC and UMaine have systematically investigated the performance of ADCF turbines by varying design parameters including solidity, aspect ratio, foil shape, number of foils, and foil angle of attack. This collection of data enables verification of analysis and design tools, and provides insight into improvements for future analytical development. As a result of this experimental work, substantial analytical work has been performed to develop a deeper understanding of the vortex flow dynamics associated with ADCF turbines.

In addition to conducting experimental tow tank work, students at UMaine have been developing analytical codes based on vortex modelling tools to predict cross turbine behavior. These codes operate by tracking the shed vorticity from the rotating turbine foils and modulating the free stream flow in response to the vorticity in the turbine wake.

Each ADCF turbine used in a TidGen device (there are four total) contains a set of four foils mounted into the TGU using spokes and a series of mounting frames.

The foils, spokes, and mounting frames are constructed of a fiber-reinforced composite. The foils are National Advisory Committee for Aeronautics profile airfoils with a blunt and rounded leading edge and a chord length of 14 in. The foils are arranged in a barrel shape, and are twisted 90 degrees to reduce torque variation and improve the turbines starting behavior. The turbine’s diameter is 9.2 ft. at the center and 8.5 ft. at each end. Axial length of each turbine is 18.4 ft. There are no yaw or pitch controls.

approval of an installation plan by FERC’s Division of Dam Safety and Inspection, the project installation began the following month. Pile driving operations secured the bottom support frame to the seabed and the TidGen TGU was installed in August.

The FERC pilot project license boundary for the project encompasses the proposed development area and includes both submerged and land-based equipment.

The in-water components, located within a 60-acre submerged land lease, granted by the Maine Bureau of Public Lands of the Department of Conservation, contains the TidGen device; bottom support frame; environmental monitoring equipment; underwater power; and data cables. The components are marked at the surface by United States Coast Guard approved private aids to navigation (corner hazard buoys).

The foundation design for the TidGen device consists of a pile-bent arrangement made up of ten steel piles, each with a 30-in. diameter and 0.5-in. wall thickness.

The piles were designed to vary in length due to bottom sediment depth, with each driven to the top of the bedrock and protruding 15-plus ft. above the seafloor.

The bottom support frame for the device was deployed on the seabed in March 2012. This acted as a template for the driving of piles to secure the foundation in place.

Power and data cable The power cable delivers electrical power from the TidGen device to the on-shore station. The cable was connected to the device and delivers to shore a nominal 800 volts of DC at a maximum current of 200 amps.

Licensing ORPC received its pilot project license for the Cobscook Bay project from FERC in February 2012. After receiving (22) marine technology July 2013

Location of the Cobscook Bay project near Eastport, Maine. www.sname.org/sname/mt

The underwater power and data (P&D) cable route was chosen after survey results indicated the fewest obstacles to cable laying, such that little or no predeployment clearing of obstacles was required. Based on consideration of environmental and safety concerns, ORPC buried the P&D cable at all feasible locations along the cross-current portion of the cable route to a depth of approximately two ft. ORPC initially proposed burying the underwater portion of the cable using jet-plow technology. However, the installation was completed using a modified shear plow to further reduce environmental disturbance.

Subsea cable installation occurred in July 2012, and began with the barge moored at the offshore cable terminus where the shore cable termination anchor was deployed.

The deployment barge was then moved along the cable transects, dispensing cable from the deployment reel as it advanced. Once the cable was laid along the seabed, the barge was stopped and the shore-side cable end was transferred to shore for completion of the on-shore cable run.

Following the laying of the outboard cable transect, the cable was secured by divers with anchors embedded into the cobble substrate. In locations where penetration did not occur due to hard substrate, the cables were stabilized by the installation of 4 ft. long iron U-shaped staples at intervals of approximately 25 ft.

The underwater P&D cable burial in the intertidal zone was performed at low tide using an excavator with a narrow width bucket to minimize disturbance. The cable was buried up the beach at a depth of 3 ft. and re-covered with beach material. Trenching continued directly inland to the on-shore station, located approximately 400 ft. from the mean high water line.

The TidGen TGU 001was placed on a floating platform, moved to the deployment location, and lowered to the bottom support frame using a heavy lift crane. Guide www.sname.org/sname/mt

cables were used to orient and direct the TGU to the bottom support frame. These operations were conducted at slack neap tides. A series of locking connections were actuated by divers, equipped with a torque tool to connect the TGU to the bottom support frame. Final connection, calibration, and positioning were completed after the TGU was attached to the bottom support frame.

The TidGen TGU is 98 ft. in length and is attached to a bottom support frame, which holds the TGU in place approximately 15 ft. above the sea floor.

Photo by Jeff Hains.

Project operation Bangor Hydro Electric Company verified first power from the project to the grid in September. Electricity is delivered by underwater P&D cable to the on-shore station where it arrives at 900 v DC. It is converted to three-phase AC at a frequency of 60 Hz and 480 v to synchronize to the electrical grid. A step-up transformer boosts the voltage before connecting with the grid.

ORPC participated in upgrading three miles of utility poles and service lines leading from the on-shore station to deliver the power to electric customers.

The power system is monitored from the on-shore station, which has the capability to start, stop, and monitor it.

Data, video, and instrumentation readings are transmitted by data cable bundled with the power transmission line.

All major system components are instrumented and monitored for operational characteristics and environmental/ ecological study, with data collected to document and validate project performance. The environmental monitoring tower, equipped with Simrad instrumentation to monitor marine life interaction with the TGU, was deployed in August.

The on-shore station contains all necessary electrical interconnection equipment as well as applicable environmental monitoring equipment. It houses a SatCon grid-tie power inverter and a supervisory control and data acquisition system.

Conducting monitoring activities in a high-energy marine environment, coupled with operating new July 2013 marine technology

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Table 1. Environmental Monitoring Plans Study Plan

Methodologies

Acoustic Monitoring Plan

easure noise using drifting noise measurement M equipment (underwater listening devices on spar buoy)

Benthic (sea floor) and biofouling monitoring plan

ive surveys before and after deployment (both benthic D and biofouling)

Fisheries and marine life interaction monitoring plans

se vessel mounted and underwater sonar devices to U determine number and depth of fish.

Hydraulic (water movement) monitoring plan

S tudy velocities and harmonics using acoustic doppler current profilers. Study sediment thickness using side-scan sonar scour and diver inspection.

Marine mammal monitoring plan

Visual observations

Bird monitoring plan

Visual observations from shore and boat

turbine technology, is challenging. We established an approach that combines innovative data collection methods and technology with an adaptive management approach.

In consultation with resource agencies and technical advisors, we developed environmental monitoring plans to assess marine life interaction with the power system.

Table 1 outlines these plans.

We also developed an adaptive management plan as required by the FERC pilot project license. This plan is an integral part of our implementation of the project and provides a strategy for evaluating monitoring data. It also enables us to make informed, sciencebased decisions to modify monitoring as necessary to maintain levels of effort that are proportional to the environmental risk. The plan, therefore, was designed to be modified within the project timeline and acknowledges that elements such as key environmental uncertainties, applied studies, and institutional structure may evolve over time. The plan has worked well for the agencies, stakeholders, and our organization as the project evolved from a concept to the first pilot installation and operation.

Environmental monitoring and best practices In addition to implementing environmental monitoring

LEADING EDGE

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plans as required by the FERC license, ORPC conducted monitoring and mitigation for pile driving to install the bottom support frame. This effort demonstrated the effective use of monitoring, mitigation, and adaptive management as a vehicle to modify the license, and the development of best management practices to minimize risk to the marine environment.

We obtained an incidental harassment authorization (IHA) from the National Oceanic and Atmospheric Administration – National Marine Fisheries Service, Office of Protected Resources, in March 2012. The IHA process was required due to the potential for the associated noise levels generated during pile driving. In addition, the FERC license for the project established a restricted period for pile driving between April 10 and November 7 of any year.

The contractor used several pile driving hammer techniques during the installation. The primary means was a vibratory hammer, which produced continuous noise levels. The secondary means was a diesel impact hammer, which produced a more acute, instantaneous noise source.

Environmental monitoring was conducted by leading scientists and experts during pile driving activities and included the following: • in-air acoustic monitoring on a nearby island and at the on-shore station

TRAILING EDGE

Airfoil of the type used in ORPC’s ADCF turbine, with a blunt and rounded leading edge and a chord length of 14 in. www.sname.org/sname/mt

• hydroacoustic monitoring in the near field (from the deployment barge) and at various far field ranges (100, 1,000, and 2,000 m) • marine mammal observations located on vessels anchored around the installation site for all pile driving activity and additionally from land stations for three events • marine mammal mitigation measures • bird survey from nearby shore.

Results of monitoring during pile driving activities demonstrated minimal impact to the environment.

Source levels measured during impact and vibratory pile driving were below the thresholds of concern for Atlantic salmon smolt. Although there were sightings of birds and harbor seals in the vicinity of the project area both before and after pile driving, their responses to pile driving noise were minimal.

Mitigation measures used during pile driving were successful in maintaining acoustic source levels within acceptable ranges and minimizing impacts to the environment. These measures included wood sound absorption devices installed in the head of the impact hammer and a “soft start” that initiated pile driving at less than 100% energy for both hammer types. In addition, modifications made by the contractor to the physical connection between the pile and the follower alleviated initial acoustic spikes.

First report In March 2013, ORPC submitted its first annual environmental monitoring report for the project to FERC. The report details the construction, installation, and operational activities of the project’s phase I and describes environmental monitoring conducted, including methods used, and the vital role of the project’s adaptive management team.

Results to date indicate significant achievements that contribute to our overall understanding of device interactions in Cobscook Bay, and there was no observed adverse interaction of the power system with the marine environment. The entire monitoring report can be found at http://www.orpc.co/permitting_doc/environmental report_Mar2013.pdf

Power purchase agreement The power purchase agreement is the mechanism that enables ORPC to bring electricity to market through a long-term contract with Bangor Hydro Electric Company. This opportunity was made possible by www.sname.org/sname/mt

Maine’s Ocean Energy Act of 2010, which allowed up to 5 MW of tidal energy production. This was adopted into law unanimously by the Maine legislature, who viewed it as a vital economic development tool. In implementing the legislation, the Maine Public Utilities Commission (PUC) established criteria that structured the terms and conditions of the contract and then administered an international competition for tidal energy developers through a request for proposal process. The PUC selected ORPC, noting that the economic benefits of our project exceeded the ratepayer cost over the life of the contract by a factor of nearly two.

Hydrok inetic technologies have t he potential to harness a vast but as yet untapped renewable energy resource. Nearly 70% of the earth is covered by water; most of this water moves constantly and predictably, and some of it moves with great force.

Tidal, river, and deep-water ocean currents f low in all regions of the world, often near major population centers where electricit y is in constant demand. Along with other hydrokinetic technology companies, we are just beginning to exploit this tremendous worldwide market opportunit y. MT

ABOVE: A turbine is prepped for installation at the Cobscook Bay project.

Photo by Jeff Hains.

BELOW: The bottom support frame being deployed on the seabed in March 2012.

Jarlath McEntee is vice president of engineering and chief technology officer at Ocean Renewable Power Company.

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WEC Development AND Commercialization How the United States Navy is approaching renewable ocean energy

By Cmdr. Rob Cohen

The proposed wave energy test site, as seen from the shore of Marine Corps Base Hawaii at Kaneohe Bay, Oahu. In the foreground are an electrical junction box and conduit that carry the electrical power from the wave energy converters onto the base.

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T

he United States Navy has been supporting ocean renewable energy research, development, testing, and evaluation (RDT&E) since the late 1990s. Although there are many types of renewable marine energy sources (tidal and currents, wave, thermal, wind, solar, conventional hydropower, and others), the navy has focused its electricity generation efforts on tides, currents, and waves.

A specific area of interest has been the researching of technologies capable of harnessing the inherent energy in ocean waves and converting it into usable electricity. As the name implies, wave energy converters (WEC) change or convert wave marine energy to electricity.

WEC efforts began more than a decade ago as the navy sought alternative ways to generate power to support remote sensing platforms, such as sea-based radars, communication systems, and other strategic sensors.

Once the proof of concept phase was completed and it was determined that harnessing renewable energy from the ocean was a viable option, the navy continued its RDT&E program and partnering efforts to develop and test WEC technology. The navy sought to further test the maturation of a WEC prototype that could operate in a specific wave regime, survive in an ocean environment for an extended period of time, and supply electricity to a grid connection at a navy or marine corps shore facility. To meet these requirements, the navy’s Office of Naval Research issued a contract solicitation via their Small Business Innovative Research program. A WEC prototype was subsequently installed and tested in a shallow testing area located offshore of Mokapu Peninsula at Marine Corps Base Hawaii (MCBH) located in Kaneohe, on the island of Oahu.

WEC program transfer The navy then transferred contractual oversight and operational management of the wave energy program to the Naval Facilities Engineering Command (NAVFAC), a navy systems command with the contractual authority and technical expertise necessary to further the development of the navy’s RDT&E efforts. NAVFAC’s Engineering and Expeditionary Warfare Center (EXWC) located in Port Hueneme, California (formerly the Naval Facilities Engineering Service Center), was given the responsibility to further create, manage, coordinate and execute the navy’s WEC test and evaluation program. www.sname.org/sname/mt

The EXWC provided specialized engineering, technology development, lifecycle logistic services, and contractual oversight of the wave energy program. Other NAVFAC commands assisted in this effort, providing essential environmental subject matter expert support, and onsite engineering and public affairs coordination. MCBH provided the host site, local coordination, onshore construction, and cultural liaison support.

Major milestone In 2003, the project achieved a major milestone. A Finding of No Significant Impact was signed for the National Environmental Policy Act (NEPA) environmental assessment that was conducted. Shortly thereafter, contractor designed and fabricated mooring, anchors, undersea cables, and an undersea junction box were installed at the berth. An existing building on base was used to house onshore electrical power and control equipment.

Between 2004 and 2011, the contractor successfully operated three generations of their WEC at the site, delivering electricity from the device to MCBH’s power grid. When the successful testing period was complete, the contractor removed the last WEC from the site in late 2011. The navy now intends to use this site as a shallow water test site (SWTS) for a new round of WEC testing.

The secretary of the navy’s energy goals emphasize energy security, independence, and a movement away from a reliance on petroleum products, which will consequently increase the use of alternative energy.

Specifically, the navy will: • Reduce non-tactical petroleum use: By 2015, the navy will reduce petroleum use in the commercial fleet by 50% • Increase alternative energy ashore: By 2020, the navy will produce at least 50% of shore-based energy requirements from alternative sources, and 50% of navy installations will be net-zero July 2013 marine technology

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WEC Development

& Commercialization

Location of the SWTS and DWTS, Kaneohe Bay, Oahu, Hawaii.

• Increase alternative energy use navy-wide: By 2020, 50% of total navy energy consumption will come from alternative sources • Use energy efficient acquisition strategies: Evaluation of energy factors will be mandatory when awarding contracts for systems and buildings • Sail the “Great Green Fleet”: The navy will demonstrate a Green Strike Group in local operations by 2012 and sail it by 2016.

To help meet these goals, the navy developed a holistic strategy focused on assessing and leveraging the full range of available and emerging technologies, including nascent marine and hydrokinetic energy technology. First, standardized Department of Defense (DOD) descriptions of technology maturity levels, known as technology readiness levels (TRL), were used based on a numeric scale ranging from 1 to 9. As a particular technology progresses along the TRL continuum, the table categorizes the development process. TRL 9 is attained when the technology successfully completes operational test and evaluation protocols and is considered to be commercially mature.

Second, a recently formalized technology approach was used. NAVFAC focused on meeting the specific energy needs of the navy while leveraging the size and resources of many federal agencies and industry. Technologies were assessed and separated into three levels of commitment: “watch” (maturing technologies and invest when and where viable); “partner” (to develop needed technologies with other government organizations and or industries); and “lead” (development of mission critical technologies).

Benchmarks for watch technologies include projects that typically fall within TRLs 1 through 5 and are developed by DOD research organizations, academia, and/or industry. NAVFAC monitors watch technology development efforts to facilitate follow-on demonstration and validation (dem/val) requirements.

Watch technologies are characterized by having a high level of technical or operational risk, and require significant RDT&E resources to assess these risks. They also would otherwise develop without navy investment, or are being developed by another service, academic institute, or industry.

Partner technology projects typically fall within TRLs 5 through 9 and are characterized by resolving a technology gap shared by other military services, agencies, or industry. Partner technology projects may require navy funding for dem/val efforts to support expedited technology integration into the navy shore infrastructure.

Lead technology projects, like partner technology projects, typically fall within TRLs 5 through 9, but are characterized by addressing a navy-unique technology gap. Lead technology projects are principally funded by the navy and managed by NAVFAC’s technology officer. Successful dem/val of lead technology projects are recognized by the appropriate NAVFAC technical authority and then become available for integration into the navy shore infrastructure.

The final assessment resulted in a NAVFAC proposal to develop a wave energy test site (WETS) that would effectively meet specific goals, including two very important objectives. One is promoting the RDT&E efforts of WEC devices that would eventually lead to full-scale (28) marine technology July 2013

commercialization capable of producing reliable, secure, efficient, and environmentally friendly renewable energy for navy bases worldwide. The other objective is that secondary, tertiary, and subsequent impacts from WETS research would help the navy reduce its dependence on fossil fuel and emissions, thereby helping to reduce the risk of environmental impacts associated with fossil fuel in the energy production process.

WETS is a concerted effort, with the navy leading the technology development while partnering with other federal agencies, academia, and industry to further the acceleration, development, and commercialization of renewable ocean energy technologies and devices.

WETS concept The EXWC determined that the WETS could be a two-phased project comprised of two separate testing areas located offshore of MCBH. These testing areas were eventually classified as the existing SWTS and a deep-water test site (DWTS) to be planned.

In early 2012, representatives from NAVFAC and the Department of Energy (DOE) Water Power Program worked to develop a synergistic approach to ensure WEC developers had an opportunity to test their devices at the SWTS. In preparation to receive another WEC at the SWTS, NAVFAC sponsored a renewable ocean energy conference in Hawaii. The conference was an opportunity to provide information to companies interested in developing new energy technology resources for coastal navy and marine corps installations. Forums included a discussion on wave www.sname.org/sname/mt

The DWTS will be able to test and evaluate more technologically mature, larger-scale WEC devices capable of producing up to one megawatt of power. energy initiatives at MCBH, as well as opportunities afforded to WEC developers.

The SWTS is an existing berth located 6/10 of a mile offshore of MCBH at a depth of approximately 100 ft. This site contains existing infrastructure capable of supporting the testing and evaluation of 1/4 to 1/2 scale systems. The 2003 environmental assessment conducted for this site identified only a point absorber WEC to be tested. As a result, the SWTS is categorized to test and evaluate only this type of WEC. In May 2012, the DOE issued a financial assistance funding opportunity announcement to support the department’s Water Power Program’s goal to provide matching funds for one industry-led project that will deploy a long-term (one year) in-water WEC device at the navy’s SWTS. This grant will assist in covering developer’s costs to support pre-deployment activities, and operations and maintenance for the one-year deployment, and the post-deployment stage. The recipient of the DOE grant will enter into a cooperative research and development agreement with the navy to gain access to the test site. The navy anticipates the test and evaluation of another WEC to start at the SWTS by early 2014.

Development of the new SWTS is supported by congressional appropriations for the navy and other federal

agencies. Subsequent to annual appropriations, the DOE and the Department of the Interior (DOI) participated in cost sharing efforts with the navy via agency-initiated fund transfers. The navy partnered with the DOE and DOI to conduct site analysis, environmental assessments, build-out, commissioning activities, and operation and maintenance tasks at the SWTS. The DOE is supporting site characterization studies and meteorological and oceanographic monitoring for both sites. The DOI also funded the University of Hawaii’s National Marine Renewable Energy Center to support design efforts for the DWTS.

Deep-water test site The DWTS will be able to test and evaluate more technologically mature, larger-scale WEC devices capable of producing up to one megawatt of power. The devices will be classified at a higher energy output than those being tested at the SWTS. Building on the technology tested at the existing SWTS, NAVFAC is working towards completing an environmental assessment for the DWTS. Initial plans include two separate berths installed at depths of 196 f. and 262 ft., both approximately 1.5 miles offshore of North Beach at MCBH. As part of the DWTS development, it is anticipated that additional wave measuring buoys and other data gathering and research devices will be installed in the vicinity of the WEC devices in order to gather and baseline oceanographic and environmental data. The potential effects of the specific WEC devices to be tested at the DWTS berths will be subject to evaluation through additional NEPA environmental reviews. The planned commissioning for the DWTS remains on schedule for late 2015.

The area of responsibilities for the DWTS.

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WEC Development

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The two deep-water berths would each provide mooring and testing locations for one oscillating water column or point absorber. Submarine and terrestrial cables would transmit WEC device data and electrical power to an onshore facility at MCBH where it would be processed.

NAVFAC and the DOE are working together to capitalize on the success of the SWTS. Discussions are ongoing to solidify the partnership for the development and operation of the DWTS. NAVFAC is encouraged by the interest shown in the SWTS and looks forward to working with its industry partners.

Lessons learned The success of the first SWTS is a testament to the many subject matter experts working in both the federal and private sectors.

Their participation and efforts contributed directly to the numerous accomplishments achieved by the SWTS, and specific lessons that they learned are being applied to the DWTS to ensure similar success is achieved. Following are some of the lessons learned that had the most impact on the outcome.

Objectives. The navy established clear, unambiguous objectives that were articulated to NAVFAC early in the program. NAVFAC leveraged its in-house and contracted subject matter experts to develop a comprehensive plan designed to meet the navy’s requirements.

Technology assessment. It was essential to have a realistic assessment of the existing technologies, capabilities, and limitations. Existing technologies, technological gaps, and the position that the navy will take from a watch, partner, or lead perspective were crucial in developing a strategic and tactical approach to meeting the requirements.

Strategic partnerships. The partnerships with other federal agencies, academia, and industry proved invaluable in ensuring that the SWTS was sufficiently resourced to create a complete and usable site capable of meeting the general objectives of the project. It was imperative to understand that each partner had specific objectives, and flexibility was required to ensure that all concerns were adequately addressed before moving forward. Candid discussions of roles, responsibilities, and requirements of all vested participants were essential in assuring that all stakeholders were focused on meeting the project’s goals. Additionally, the navy’s partners brought subject matter experts that were force multipliers in helping to overcome planning, programming, budgeting, and execution-related issues.

Intergovernmental coordination and community outreach.

Vertical and horizontal communication through the numerous federal, state, and local agencies proved essential during the planning phase of the SWTS. Discussions at the highest levels of federal agencies and the offices and committees of federal, state, and locallyelected officials were invaluable in ensuring that interested parties were aware of the navy’s wave energy technology strategy and proposed development. Legislative briefings played an essential role.

Local outreach actions, including briefs to neighborhood boards, (30) marine technology July 2013

The proposed wave energy test site at Marine Corps Base Hawaii, with the first WEC just visible out toward the horizon.

the chamber of commerce, native Hawaiian and ocean recreation groups, and other interested agencies made a huge impact on the positive perception and response the public had with the project.

Strategic communication planning outlining these outreach tactics was an essential part of the project’s early success, and made the local media actively interested and engaged in the site’s development and plans throughout the project’s lifecycle.

Expectation management. It was important for all stakeholders to recognize that the project was solely an RDT&E effort.

Failing to meet the established objectives was an accepted reality as there were no assurances that the intended project objectives would be met.

NAVFAC will continue to support the navy’s renewable energy goals by developing and building strategic partnerships, and will use the skill sets necessary to successfully manage the navy’s waterborne test sites to support the development and commercialization of WEC devices. The open-water sites will afford testing opportunities for developers to mature their technologies so that commercialization can be attained. The WETS infrastructure will be instrumental in better understanding and overcoming the complexities associated with bringing this form of renewable ocean energy into a suite of energy production options available to the navy. MT Cmdr. Rob Cohen is energy action officer with Naval Facilities Engineering Command. www.sname.org/sname/mt

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The SeaGen S 1.2MW with the crossbeam and power trains raised for maintenance.

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Harnessing

Tidal Velocity The free-stream tidal energy market in the U.K. and Europe

By David Ainsworth

an has been extracting energy from the tides for more than a thousand years, using tidal mills that take advantage of tidal range. One of the oldest tidal mills in Europe can be found at Nendrum in Northern Ireland, a site that dates back to 619 AD. The remains of the mill can still be seen on an island in the northwest part of Strangford Lough.

A large seawater lough that is connected to the Irish Sea through Strangford Narrows, Strangford Lough is located 20 miles southwest of Belfast. The water in the narrows rushes through at speeds up to 10 knots during the flood and ebb tides. Locally, the name Strangford, or Strong Fjord, is believed to have been given to the area by Vikings who visited the area in the 10th century.

MCT history In the narrows sits a 14 m high, 3 m in diameter black and red tower known internationally as SeaGen. The structure only reveals it’s secret when the hidden underwater components are lifted above the surface for maintenance. It is the world’s first 1 MW free-stream tidal turbine. Unlike the earlier Nendrum tidal mill, SeaGen produces energy by the flow of the water driving the tidal turbines.

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At right: A 600 kW drive train on SeaGen showing hub, gearbox and generator.

Facing Page: The Seaflow 300 kW prototype tidal turbine, which was decommissioned in 2009, is shown with the power train raised for maintenance.

SeaGen was installed in 2008 by Marine Current Turbines Ltd. (MCT), based in Bristol, England. MCT has been fully owned

by Siemens AG since March 2012. MCT’s pedigree in tidal energy demonstration programs can be traced back to 1994, when one of the company’s founding directors, Peter Fraenkel, developed a 15 kW proof-of-concept floating tidal turbine that was deployed in Loch Linnhe in Scotland.

The success of the Loch Linnhe project led to the 300 kW scaled demonstrator known as Seaflow. Seaflow was installed in the Bristol Channel 3 km from Lynmouth, Devon in May 2003 and demonstrated all the required objectives. It was decommissioned in 2009. The success of the Seaflow project led to the investment in the SeaGen S 1.2 MW device, which is now installed in Strangford Lough.

A key challenge with Seaflow was the installation. In the Bristol Channel, the tidal range is up to 9 m, with Seaflow being installed in 17 m of water at chart datum.

The 1.8 m diameter monopile was installed into a socket drilled in the seabed using the jackup vessel Deep Diver, owned and operated by Fugro Seacore. The pile was floated out to the site and then lifted by Deep Diver’s crane, using a buoyant lift technique, and (34) marine technology July 2013

lowered into the socket. The experience of the Seaflow installation was significant to the success of the SeaGen project.

The market There are other tidal energy projects in the world, such as La Rance in France and Annapolis Royal in Nova Scotia. But these are tidal barrage projects, which rely on tidal range (rise and fall of the tide) driving low head turbine generators, rather than freestream tidal (tidal velocity). La Rance was built in the 1960s with Annapolis Royal coming online in the 1980s. There are many other potential locations where tidal range projects could be built, and while some are in construction (such as in Korea), others have been considered for decades (such as Severn Barrage in the U.K.). The capital cost and perceived environmental impacts of these projects have proved a significant challenge to their delivery.

The global market for free-stream tidal energy convertors is estimated to be 300 TWh/year. Countries with a significant tidal resource include the United States, Canada, the United Kingdom, France, Japan, China, Korea, Chile, Australia, New Zealand, Indonesia, India, and Russia. The market is considered big enough for major

original equipment manufacturers (OEMs) such as Siemens, Alstom, DCNS, Voith, and Andritz to invest significantly in tidal technology developers.

In the U.K., in addition to the MCT SeaGen system, a handful of 1 MW devices have been deployed for trials. These are all at the European Marine Energy Centre (EMEC) located in the Orkney Islands in Scotland. EMEC has seven tidal test berths, of which two currently have 1 MW tidal energy devices installed (Alstom TGL and Andritz Hammerfest). In the near future, they will see 1 MW devices from Kawasaki, Voith, and Atlantis Renewables Corporation.

The U.S. also has a nascent tidal energy industry, with Maine-based Ocean Renewable Power Company and Verdant (in New York) having had notable successes in the last few years. In addition, there is a proposed deployment of demonstration tidal turbines in Puget Sound, Washington.

Market development The U.K. has the best tidal resources in Europe, and the next phase of market development is already in progress there. Four multiple device arrays will be installed in the U.K. in 2014/2015. The key issue with these early arrays is that they will be too expensive www.sname.org/sname/mt

for any single company to build, with challenging investment returns for investors.

In addition, the risks will be too high with the technology innovation for conventional financial investment, which is compounded by the bleak worldwide economic situation.

Thus, the U.K. government has recognized that these projects require capital grant support to attract investment. All four of the projects proposed for 2014/2015 are receiving some form of grant support, and are shown in Table 1.

In addition, The Crown Estate in the U.K. has offered up to £10 million finance for two projects. The Crown Estate controls the seabed in the U.K. and leases it to all marine operations, including aggregate

extraction, offshore wind, oil, gas, tidal, and wave projects.

The Crown Estate also has run two strategic licensing rounds, which have resulted in the issuing of agreements for lease for tidal projects totalling nearly 1,300 MW in U.K. territorial waters. Some 200 MW of these leases are located in Northern Ireland, and more than 1,000 MW in the Pentland Firth on the northern coast of Scotland. Most of these projects are being progressed on a technology-neutral basis, with the anticipation that there will be a variety of technologies to choose from when the projects are built from 2017 onwards.

Several of the leases are held by major U.K. electrical utilities, including Scottish

Power, Scottish and Southern Electricity, and Bord Gais in Ireland.

France is also exploring opportunities to develop a tidal industry and exploit their tidal resources in Brittany and Normandy. Both Gaz de France and Electricite de France (EdF) are active in their home French tidal markets.

EdF has been developing the Paimpol 10 MW tidal array for several years and should be generating in 2013.

The next significant opportunity could be the Bay of Fundy in Canada. The Fundy Ocean Resource Centre has four tidal test berths for the deployment of demonstration devices. These berths will be occupied by Minas Basin Energy, using Siemens Marine Current Turbines devices; Atlantis Renewable

Table 1: Multiple Device Arrays to be Installed in the U.K. Location

Owner

Devices

Grant Support

Project Status

Skerries, Wales

SeaGeneration (Wales) Ltd.

5 x Siemens MCT SeaGen S 2 MW

£10 million from U.K. government as part of the Marine Energy Array Demonstrator program

Consents granted in February 2013

Kyle Rhea, Skye, Scotland

SeaGeneration (Kyle Rheas) Ltd.

4 x Siemens MCT SeaGen S 2 MW

£15 million from EC NER300 fund (New Entrants Reserve)

Consent decision expected late 2013

Sound of Islay, Scotland

Scottish Power Renewables Ltd.

10 x 1 MW Andritz Hammerfest

£16 million from EC NER300 fund (New Entrants Reserve)

Consent decision expected July 2013

Inner Sound, Stroma, Scotland

MeyGen Ltd.

3 x 1.4 MW Andritz Hammerfest

£10 million from U.K. government Marine Energy Array Demonstrator program

Consents granted March 2011

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The tide flowing past the SeaGen pile in Strangford Lough. During spring tides, the flow will peak at over 9 knots.

Corporation; and Alstom. The fourth berth is currently vacant.

Straightforward concept Tidal stream is considered analogous to offshore wind turbines in many areas. The rotors are driven by the tidal currents and not the wind.

However, as sea water is 830 times denser than air, for the same power output a tidal turbine rotor will be smaller than a wind turbine. The turbines, though, run at a much lower speed.

The tower of the SeaGen tidal energy convertor supports a cross beam that is 22 m tip to tip, and at each end of the cross beam are the two power train units rated at 600 kW each. The power trains are similar in architecture to those used on wind turbines. The Strangford power trains comprise a twoblade 16 m-diameter rotor, which is designed to rotate at 14 rpm when the tidal velocity is 2.4 m/s. The blades are pitch control to maximize the energy capture at part load, but also to regulate the rotor speed at tidal velocities of greater than 2.4 m/s.

The pitch control system also enables the blades to be positioned so that they can generate on ebb as well as the flood current.

The rotors are connected to a gearbox with (36) marine technology July 2013

a ratio of 70:1 driving a conventional generator. As the turbine generates across a wide speed range, the output of the generator is fed through a rectifier and then inverted back to mains frequency. Each power train is fully independent, so the system can generate with one turbine in the event of a system fault.

Fundamentally, the concept is straightforward. The challenges come in installing the technology; maintaining it; making the technology last for 20 years in a marine environment; and demonstrating that it is environmentally benign.

The Seagen S power output will be increased from 1.2 MW to 2.0 MW for the Kyle Rhea and Skerries demonstration arrays mentioned earlier.

Installation One of the key enabling technologies that has supported the evolution of the tidal energy demonstrators installed at Lynmouth, EMEC, and Strangford has been a combination of the vessel and marine experience that has been developed for the offshore construction and support industry over the last 20 years.

The installation cost for a tidal demonstration project is a significant portion

of the overall project budget due to the cost of the vessels and the balance of the installation plant. There will have to be a significant investment in installation equipment to reduce the overall costs of tidal projects so that they become comparable with offshore wind and other forms of renewable technology. This would result in a significant reduction in the requirement for revenue support mechanisms and capital grant support.

The Seaflow project in Strangford used a jackup barge and large-diameter pile top drill that was used for marine construction projects. The Seaflow device was installed in water 17 m deep at chart datum. SeaGen can be installed in water depths up to 40 m, so jackups that can stand in deeper water with higher capacity cranes will be required in the future.

Fortunately, these requirements are the same as the offshore wind industry. The jackup barge operators have responded to this requirement, so there are several jackup barges/vessels in operation in Europe that can meet this requirement. The challenge is the high level of forecast use in the offshore wind construction market.

At EMEC, there have been several successful demonstrations of deployment and recovery of tidal devices using dynamically positioned (DP) vessels. These vessels typically have been developed for the oil and gas industry; therefore, the vessel capabilities, size, and hence costs are significantly greater than required for the tidal industry.

In response to the success of the DP vessel operations in strong tidal environments, there are core initiatives to develop dedicated vessels that will meet the requirements for tidal turbine installation and maintenance and will have a significantly lower charter day rate.

These vessels can also be used for the wave sector, cable installation, and construction.

Mojo and KML in the U.K. both are designing vessels to meet these requirements.

A strong foundation There are three favored forms of foundation.

The first is a monopole approach, in which a large diameter hole is drilled in the seabed. www.sname.org/sname/mt

The Strangford power trains comprise a two-blade 16 m-diameter rotor, which is designed to rotate at 14 rpm when the tidal velocity is 2.4 m/s.

This is used by Voith at EMEC and MCT’s Seaflow in Lynmouth.

The second type uses pin piles. The structure either has a tripod or quadrapod, with each of the feet pinned to the seabed using a small pile, as used by Alstom TGL at EMEC and Siemens MCT SeaGen in Strangford Lough.

The third option is gravity, in cases where the structure is heavy enough to withstand the drag loads, as used by Atlantis Resource Corporation at EMEC. The industry may converge on a pin-piled solution if the costs are reduced. Already, drilling specialists such as Bauer (Germany) and McLaughlin & Harvey (Northern Ireland) are developing seabed drilling equipment that can be operated via umbilicals from DP vessels or moored barges.

Subsea cabling The design of subsea cables in a strong tidal environment will be challenging. The majority of the projects that we have experience with are scoured rock.

In Strangford Lough, the issue was avoided by horizontal directional drilling (HDD) the cable duct from shore. A 300 mm diameter drill bore a hole, which was completed 12 months before the turbine was deployed. This technique could be used for devices located within about 1 km from shore, but any further than that and HDD may prove challenging.

EMEC has probably the best experience with surface-laid cable in high tidal currents, with their first cable installations now approaching seven years old. This experience will help with the analysis of cable life in these environments.

If cable protection is necessary, then rock dumping or using armor shells on the cable www.sname.org/sname/mt

are feasible. However, the best strategy will be to design a cable route affording the best cable stability, and laying the cable in line with the strongest current rather than perpendicular to it.

All projects will benefit from a cost benefit study with respect to optimized cable route, cable protection, and replacing the cable within the project lifetime.

In multiple device arrays, the architecture of the subsea cabling and power hubs will be essential. The Siemens MCT SeaGen S technology is fully grid compliant. The final output transformer can be selected to suit the local grid voltage; in the U.K., that typically will be 11 KV or 33 KV. The surface-breaking feature of the SeaGen S device neatly sidesteps the requirement for quick release dry or wet mate connectors.

The current market requirement is for dry and wet mate 1 MW connections at sub 11 KV

ratings. We foresee a requirement for 3 MW, 33 KV dry mate connections in the next 5-10 years to enable tidal technology to evolve.

Turbine rating increases The current trend in offshore wind is for taller structures with larger diameter turbines.

Siemens is now testing a 6 MW turbine with a 120 m rotor diameter. Other developers have considered 10 MW wind turbines.

Tidal turbines are constrained by water depth. Practically, rotor diameters of 30 m could be achieved; however there are constraints with depths. First, there are minimum depth clearances of the rotor tips to avoid navigation issues and the impact of waves on performance of 6-8 m. Also, in the water column, most of the tidal energy is in the upper 50% of the column. And most of the U.K. tidal resource is in 40-60 m of water depth.

This would suggest that a 30 m rotor would be optimal for a 50-60 m water depth.

A 30 m rotor with a rated tidal velocity of 2.5 m/s would produce 3.4 MW. MCT’s strateg y is to deploy devices with multiple turbines per foundation.

As the foundation cost is nominally constant per device, having two generators

All routine maintenance on the SeaGen can be can conducted from a low-cost rigid hull inflatable boat.

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Maintenance access to SeaGen in Strangford Lough has been key to the success of the project.

per installation drives down the installed cost per MW.

The environment When the SeaGen project development started in 2003, it became obvious that it was not just about the technology development. It was essential that equal focus was given to the environmental aspects of the project. For the market to develop, MCT had to demonstrate that SeaGen would not have an impact on the environment into which it was being installed.

MCT worked with a team of world-class experts including • SMRU Ltd., which provided expertise on marine mammal science and marine mammal detection • Queens University Belfast, which provided expertise on benthic ecologies, monitoring, and wake assessments • Royal HaskoninGDHV, which provided project management, development of the environmental management programme, consent support, and environmental impact assessments.

In Strangford, the key receptors that were considered during the project were the common seals, harbor porpoises, and benthic communities. The Lough also has frequent visits from other protected species, including bottle-nose dolphins, minke whales, threshers, and basking sharks.

The environmental monitoring program was completed in 2012 to the satisfaction of the regulator.

The step from the env ironmental assessment to the granting of the consents of the Skerries 10 MW array has been supported by the outcome of the Strangford environmental monitoring program. The planned 10 MW demonstration arrays will have to be monitored to support the development of larger arrays.

Reassurance and challenges The progress of the tidal energy sector in the U.K. since Seaflow was installed in 2003 has been slower than predicted, but has resulted in reassured investment in the sector. Several (38) marine technology July 2013

OEMs (Siemens, Voith, Alstom, Andritz and DCNS) have invested in the sector in the last 12 months, which has provided significant reassurance to the U.K. government and the U.K. electrical utilities.

The sector is not without future challenges. The current costs are high and need significant capital grant support and revenue support to gain investment. The major OEM involvement will help to drive down the capital costs of the equipment, but installation represents a significant part of the overall cost. Installation contractors are making significant investments in designing vessels and demonstrating seabed

drilling capability, which should result in significant installation cost savings.

Other enabling technologies will be required in the next few years such as largercapacity dry and wet mate connectors.

In the last 5 years, there has been a significant increase in demonstrated success, with our SeaGen device in Strangford Lough leading the way. There are other 1 MW devices in the water, with Andritz Hammerfest and Alstom TGL now both having generated 1 MW into the grid. MT David Ainsworth is business development director at Marine Current Turbines Ltd. www.sname.org/sname/mt

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Critical

Role he marine renewable energy (MRE) industry is still in its infancy. However, industry leaders already have recognized that, to reap the potentially huge economic and social benefits available from harnessing the energy of waves, tides, ocean currents, and ocean thermal differentials, an internationally recognized set of standards and guidelines would need to be established.

Furthermore, they recognized that those standards and guidelines, once established, would need to be applied and upheld by reputable third-party certifying bodies so that other important stakeholders including project developers, regulators, financiers, and insurers could contribute to the development of this promising new industry.

At the same time, however, to enable innovation and creativity to continue in an industry that is still conducting applied research into the fundamental system responses of marine energy harvesting (40) marine technology July 2013

Standards and certification in the marine renewable energy industry

By BILL STABY

devices operating in a dynamic and harsh environment, these standards cannot be overly prescriptive.

Standards are particularly important to the MRE industry because, at present, there are dozens of different technologies competing for very few ocean deployment opportunities and thus standards can serve as a fair basis for making technology selection decisions. In addition, modeling the behavior of ocean energy systems is quite difficult when compared to, for example, wind energy. This adds another layer of complexity and uncertainty, which can be mitigated by the development and application of standardized resource measurement methods.

Ideally, when applied alongside a welldesigned certification process, standards can guide technology developers through each step of the engineering lifecycle and yield better designs while saving significant amounts www.sname.org/sname/mt

A wave measurement mast characterizes waves being produced by a wave maker in a wave tank in New Jersey. This type of test program would use standards for testing reduced-scale wave energy converters.

of time and expense. Similarly, standards and certifications can guide project developers through technology selection and commercial feasibility analyses by identifying risks and providing means to eliminate or gain protection from them. The MRE industry has established these as guiding principles of standards development and conformity assessment to maximize the chances that ocean energy conversion technologies become part of our clean, renewable energy future.

Development work Since 2007, the United States has been actively engaged as a key participant in the International Electrotechnical Commission (IEC) Technical Committee 114 (TC-114), which is developing and maintaining technical specifications and standards for wave, current, tidal, and ocean thermal energy resource characterization and conversion device performance assessment.

Along with the International Organization for Standardization (ISO), IEC is a premier worldwide developer and publisher of specifications and standards and, as such, has a strict mandate to ensure that engineering systems developed anywhere in the world are held to consistent and well-understood design and operating principles.

TC-114 has 22 member countries in North America, Europe, Asia, and Australia. All official communications between the United States and the IEC with respect to TC-114 business are required to be routed through the American National Standards Institute (ANSI), which serves as The United States National Committee. To conduct day-to-day activities related to representing the United States on TC-114, ANSI has approved the formation of a technical advisory group (TAG). www.sname.org/sname/mt

Standards can guide technology developers through each step of the engineering lifecycle and yield better designs while saving significant amounts of time and expense.

Among other things, the TAG recommends appointments to various sub-committees, coordinates communications among TAG members, provides periodic progress reports, and assists in the creation and management of the TAG operating budget. All members of the U.S. TAG must be dues-paying members of ANSI in order to participate in TC-114 activities. At present, there are approximately 40 members of the U.S. TAG who serve on one or more of the 11 sub-committees (called shadow committees, or SC) that are developing technical specifications and standards.

Marine energy technical specifications and standards are being developed in 11 areas as follows: • PT62600-1: Terminology • PT62600-2: Design requirements for marine energy systems • PT62600-10: Assessment of mooring systems for marine energy converters • PT62600-20: Guideline for design assessment of ocean thermal energy conversion systems • P T62600-30: Electrical power quality requirements for wave, tidal, and other water current energy converters • PT62600-100: Assessment of performance of wave energy converters in open sea

• PT62600-101: Wave energy resource characterization and assessment • PT62600-102: Wave energy converter power performance assessment at a second location using measured assessment data • PT62600-103: Wave energy conversion scale testing • PT62600-200: Power performance assessment of electricity producing tidal energy converters • PT62600-201: Tidal energy resource characterization and assessment.

Each standard is developed by a project team (PT), which is made up of participating countries that have interest and expertise in the specific subject matter. A minimum of four participating countries is required to establish a PT and develop a standard. Individuals participating in the deliberations of a PT embody a wide range of stakeholder interests and include representatives from government agencies, certification bodies, device developers, regulatory agencies, academia and research institutions, environmental scientists, financiers, and utility end users. It has taken an average of approximately three years from the time a PT is first established to when it issues a technical specification.

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Critical

Role Management of the work of each PT is the responsibility of an individual designated as the “convener,” and is carried out at both the international level and the individual member country level. The convener of a PT will typically assign specific “chapters” of the standard to member countries, which then direct their own SCs to complete the assignment within an allotted time. When drafts of each chapter of an emerging standard have been completed, the PTs review and make comments and modifications through a series of meetings held both in-person and electronically.

Typically, a PT will have one in-person meeting annually and several virtual meetings using webcast and telephone communications. In the U.S., the SCs typically follow the same schedule of one annual meeting and a number of electronic meetings. Currently, three of the PTs (PT62600-1, PT62600-100, and PT62600-200) have issued technical specifications, which is an interim stage that enables general comment and modification of the document before its designation as a standard. The remaining eight PTs are at various levels of completion leading to the issuance of a technical specification. As the sector develops, the need for more standards will be identified and, therefore, more PTs will be formed. It is expected that U.S. participation on TC-114 will continue indefinitely, but for at least the next 20 years.

Fairness and consistency Within the IEC there is an independent body, the Conformity Assessment Board (CAB). This body is responsible for ensuring that standards developed by the various IEC technical committees are applied fairly and consistently such that global adoption of technologies is facilitated through the creation and operation of a trustworthy system of certification and verification. The U.S. currently has three representatives on CAB working group 15 (WG 15), which is developing the certification system that will be used in conjunction with the technical specifications and standards developed by TC-114.

The objective of CAB WG 15 is to make standards relevant and widely adopted by making them accepted, trusted, and (42) marine technology July 2013

A Resolute Marine Energy wave energy converter is deployed for an ocean test program at Jennette’s Pier in Nags Head, North Carolina. Testing such as this would use several standards being developed by TC-114.

readily accessible around the world. The term “accepted” emanates from the standards themselves and is a measure of their quality and fairness. The term “trusted” stems from a robust set of detection and enforcement tools IEC has available that ensure that the certification processes are not corrupt or corrupted.

The term “readily accessible” involves, for example, automating the processes by which certificates can be posted and verified online.

If conformity assessment processes meet these criteria, the standards developed by TC-114 will be widely adopted and enforced, which benefits the marine and hydrokinetic (MHK) industry by reducing fragmentation and the temptation of countries to use standards as trade barriers.

Key initiatives CAB WG 15 is working on several key initiatives to develop a unique conformity assessment system to serve the MHK industry. These include adopting a “systems” approach, which means allowing for different levels of conformity assessment. These levels include first party certification (self-enforcement and documentation); second party certification (for example, verification of test results by organizations such as Garrad Hassan); and third party certification by classification societies well known to the shipping industry such as

GL, DnV, BV, Lloyd’s, KBS, and ABS. The systems approach also includes developing and implementing a well-designed framework for conformity assessment. This involves ensuring that conformity assessment processes can be applied at discrete stages of the technology or project development lifecycle; for example, at the concept phase; site assessment; manufacturing and assembly; transportation; installation; commissioning; operation and maintenance; and retrieval.

The goal is to provide technology and project developers a means of promptly reducing risk at each stage so as to move quickly to the next.

Another CAB WG 15 initiative is to apply standards in a risk assessment context.

Thinking of conformity assessment in a risk assessment context means making sure that overly onerous certification requirements are not applied in situations where, for example, a failure mode effects analysis would indicate minimal impact. Other examples include differentiating between when guidelines versus standards may be applied; ensuring there is a clear distinction between conformity assessment processes related to safety (certify) and performance (verify); and establishing a risk-weighted documentation roadmap. This last includes a feasibility study; a prototype certificate; a type certificate; and project certification. www.sname.org/sname/mt

In summary, the goal of CAB WG 15 is to ensure that conformity assessment processes serve the needs of all stakeholders including technology developers, project developers, insurance companies, financiers, government agencies, and the certification bodies themselves.

TC-114 and CAB WG 15 hold annual plenary meetings to review and assess progress on standards development, consider new work items, and discuss the overall strategy of TC-114 and CAB WG 15 from the perspective of needed support to the sector.

At the TC-114 annual plenary meetings, all country delegations are represented by a technical advisor (TA) and, typically, one or more others who are designated as experts.

The convener for each project team is also present to report on the progress and plans for their standards development effort.

Currently, TC-114 is led by its chairman, Neil Rondorf of the United States, and its secretary, Danny Peacock of the United Kingdom.

Each of the 22 member countries of TC-114 appoint a TA, who represents the country’s delegation and makes decisions on its behalf.

The current TA for the U.S. is your author, Bill Staby, with able support from Deputy TA Roger Bagbey of Cardinal Engineering and Secretary Arielle Wolfe of the National Renewable Energy Laboratory (NREL). Typically, each member country will also appoint a secretary agency, which, for the U.S., is the NREL, represented by Walter Musial.

The U.S. currently has more than 40 people participating in TAG management, its 11 shadow committees, and CAB WG 15, including two conveners, Bob Paasch and David Tietje, who lead PT62600-2 and PT62600100, respectively. On CAB WG 15, the U.S. is

represented by Tim Duffy, who heads global conformity assessment and standards compliance for Rockwell Automation; Jonathan Colby, a senior engineer at Verdant Power; and Bill Staby.

The U.S. is an active participant in both TC-114 and WG 15 and, as such, is both well respected and influential on both committees. This U.S. leadership position would not be possible, however, without the generous funding support of the U.S. Department of Energy’s Water Power Program and the dedication of all the people who volunteer their time to get this important work done. MT Bill Staby is founder and CEO of Resolute Marine Energy.

For more information about IEC TC-114, CAB WG 15, and the U.S. TAG, go to www.tc114.us

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Verdant’s Gen5 KHPS rotor is prepared for an in-water test at the RITE site in 2012.

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From

Demonstration

To Market

Evolving system moves toward commercial viability

By Dean R. Corren

Our company, Verdant Power, Inc., has been developing and operating kinetic hydropower systems since its formation in 2000, with a continuing goal of creating a commercially viable marine and hydrokinetic (MHK) power generation industry.

Our kinetic hydropower system (KHPS) is based on a three-bladed horizontalaxis turbine. Our approach to technology development has been stepwise, both in scale and functionality. With our fourth generation (Gen4) system, beginning in 2006, we demonstrated excellent technical performance and environmental compatibility at our Roosevelt Island Tidal Energy (RITE) project site in New York City’s East River.

Since 2010, we have been designing a commercial system (Gen5) based on the performance of the prior systems, but designed from the ground up to meet the requirements of the commercial electric power marketplace.

Concurrently, Verdant has pursued other aspects of developing and deploying a commercial system. Working with regulatory agencies to achieve permitting, we have advanced the science of resource analysis and the performance of operational environmental monitoring. In January 2012, we received the first full-scale commercial MHK pilot project license in the United States from the Federal Energy Regulatory Commission (FERC) for an array of 30 Gen5 KHPS turbines at our RITE project site.

Commercial market entry Bringing the KHPS technology to the commercial electric power marketplace requires systematic funding to advance the technology to a point that attracts financing of large-scale projects. These projects will use arrays of numerous turbines and the accompanying systems at specific water resource sites. In order for the emerging MHK energy industry to secure financing for such projects, a number of steps must be accomplished.

Reaching the goal of financing a commercial MHK project begins with a core technology that has been proved for performance, safety, and reliability. For the emerging MHK industry, international standards are now under development, a process in which Verdant is a full participant. (For more on MHK standards development, see “Critical Role,� beginning on page 40 in this issue.) Such standards,

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and the proof of compliance indicated by third-party certification, is essential for securing insurance and credible project economic analyses.

The specific project site must be fully characterized, including the entire range of energy resource, environmental, and logistical parameters. These are then applied to the proven power performance of the MHK system to derive the annual energy production, which is the output value of the project.

The site characterization also forms the basis for all of the environmental, land use, and energy production permitting activities that will be required for the project to proceed to insurability and financing for the detailed site-specific project design.

The economic models of these projects include the upfront capital expenses of permitting, compliance, manufacturing, deployment, installation, and grid interconnection. The ongoing costs of system operating and maintenance (O&M) and compliance are expressed by the operating expense (OPEX). The intense focus on the operational aspects of reliability, longevity,

and economical maintainability derives from the high costs of onwater activities. Controlling OPEX demands minimizing on-water equipment, personnel, and time, so high reliability is essential to permit extended service intervals. Turbines are maintained according to an economic servicing model by retrieving and replacing them immediately with a new or refurbished unit. The retrieved units are refurbished at an off-site facility.

A comprehensive project design also requires the commitment of an electricity purchaser (end user or reseller) to a power purchase agreement to buy the project’s power output. At this point, a credible project should be able to secure financing and proceed to construction and operation.

Technology development trajectory Verdant’s KHPS (turbine and balance-of-system) has progressed through a series of versions that have tested various aspects of the overall system at various scales from model rotors to near-fullscale complete turbines.

The Gen4 KHPS was a complete, bottom-mounted system with passive yaw (turning to capture the tidal flows in both directions) for unattended operation. It incorporated the balanceof-system components enabling grid connection of the induction generator, with full protection and monitoring. Five of these turbines were built, along with a dynamometry version that was hydrodynamically identical, but was used to test the rotor performance through the full range of water speeds and loads. These turbines were tested at our RITE site in the East River of New York City to demonstrate the basic performance of the entire system.

The status of a technology’s progress towards commercialization is ranked by the United States Department of Energy (DOE) according to its technology readiness level (TRL), which was adapted from NASA. Based on the type of development and testing accomplished, a technology can rate from 1 to 9 with TRL-1 being an untested concept, and TRL-9 being a fully-tested commercial system. The Gen4 Verdant KHPS has reached TRL-5/6 based on successful full-scale testing in the real environment at RITE. Once the commercial-type Gen5 systems are deployed and tested at RITE, they will reach a TRL-7/8 (demonstration of an actual system in its final form under expected conditions in an operational environment), with only further longevity testing and volume production required for full commercial readiness.

The Gen5 system design, which currently is nearing completion and entering the subsystem testing and fabrication stages, will be deployed and operated in phases at RITE, under the FERC license, to achieve the commercially-required extended operational periods.

Gen4 KHPS design Gen4 KHPS turbines ready for installation.

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Our Gen4 system was designed to demonstrate full-scale functionality in the East River tidal strait environment. For www.sname.org/sname/mt

During rotor blade development of the Gen5 system, blade designs were subjected to multiple independent computational fluid dynamics analyses, as were the full rotor and turbine. Shown here is a vorticity isosurface from such an analysis. Image courtesy University of Minnesota St. Anthony Falls Laboratory.

expediency, it used primarily off-the-shelf and rapidly-fabricated one-off components.

The Gen4 turbine has an open, axial flow and a three-bladed fixed-pitch downstream rotor. The entire turbine yaws passively around a fixed pylon to capture the bidirectional flow. The rotor drives a planetary gear speed increaser and an induction generator that is connected by a submarine cable and onshore switchgear to the electric grid.

The structural components were mild steel with epoxy coatings and anodic protection. The rotor blades were cast AlMag 35 on a fabricated steel hub. Hub fairings and nose and tail cones were stainless and FRP, respectively. The yaw bearings within the pylon assembly use a water-wetted high-performance plastic material. Various combinations of the Gen4 turbines were deployed and installed at the RITE project site in New York City, and operated between 2006 and 2008.

The RITE project site is characterized by a 10 m (30 ft.) depth; an exposed rock bottom; semidiurnal tides with similar flood and ebb strengths; an extreme tidal range of about 2.2 m (7.2 ft.); and water speed peaks of about 2.0 to 2.5 m/s, with brief peaks over 3 m/s.

The project was fully permitted for Verdant’s kinetic hydropower demonstration purposes, including environmental, land use, and grid connection through an exemption authority from FERC, to allow connection of the 5-turbine array to power two commercial end users.

The features of the demonstration project included: • 5 m diameter turbines www.sname.org/sname/mt

• five generator turbines rated 35 kW at 2.1 m/s • one rotor dynamometer turbine • turbines mounted on piles set into rock bottom • a multi-turbine array • a grid interconnect • 9,000-plus turbine hours of operation • 70-plus MWh supplied to the grid.

The performance of the Gen4 KHPS during the RITE demonstration project was excellent. The performance of the system was proved, from the rotor—the primary energy capture device—to the electric grid, including the turbine yaw, drivetrain, generator, cabling, control system, and switchgear.

Over 30 months, with three separate deployments of various turbines, key accomplishments included: • efficiency: 30-40% (water-to-wire) for all turbines • control: automatic and unattended • yaw: passive, with equal bidirectional performance • survivability: no debris fouling or damage • environmental monitoring: proven environmental compatibility The longest continuous operational period for an individual turbine was 60 days, or approximately 240 tides. Having completed their system demonstration function, the turbines were

The Gen4 KHPS was a complete, bottom-mounted system with passive yaw (turning to capture the tidal flows in both directions) for unattended operation. retrieved, dismantled, and inspected so that the condition of the individual components, from seals to fasteners, could inform the Gen5 design.

With the Gen4 systems having demonstrated excellent basic KHPS performance, the next generation design was begun in 2010 to meet the further requirements for a truly commercial system. To meet the commercial economic requirements described earlier, the Gen5 was designed to capture the potential for both capital and operating cost reductions.

Capital cost reduction areas included turbine, mounting, interconnect, and developed supply chain. O&M cost reduction areas included deployment, maintenance operations, ultra-high reliability, extended service interval, and long-term deployments.

The requirement for reliability and longevity is key.

Accordingly, a target 20-year life and 5-year service interval were established for Gen5.

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Further, beyond the limited-scale testing at RITE, the clear commercial potential for this MHK technology is at larger perturbine scales and power levels at deeper sites with faster flows.

Accordingly, another (related) criterion for this development has been scalability, and we have preliminarily extended the basic Gen5 design to systems of at least 10 m diameters and 250 kW per unit.

Gen5 KHPS design The Gen5 KHPS design builds upon the lessons learned from the fabrication and in-water operation of the previous generation systems. There are two fundamental differences between the Gen4 and Gen5.

First, unlike the Gen4 design, which relied as much as possible on off-the-shelf components, the Gen5 turbine has been designed based on custom components and designs and materials better suited to volume production. This has enabled dramatic mechanical integration and parts count reduction, as well as closer tailoring of the design to the environment, such as redundant sealing. Enhanced reliability and longevity have been the result, along with cost reduction.

Second, the Gen5 turbine incorporates a “failsafe” brake. This spring-applied electrically-released brake protects the rotor, drivetrain, and structure from overloads, and reduces wear. It also enables installation safety improvements. This change further entailed a significant update of system control hardware and strategy.

Rotor development To meet the requirements of longevity and scalability, in terms of strength and corrosion-resistance, an entirely new composite rotor blade was developed for the Gen5 KHPS. We were assisted in this work by the National Renewable Energy Laboratory (NREL) and Sandia National Labs under cooperative research agreements. In addition, a DOE Advanced Water Power Program award permitted further analysis by the University of Minnesota St. Anthony Falls Laboratory, and the fabrication of blades and testing of the new rotor at full scale in the lab at NREL and in the water at RITE in 2012.

As before, the rotor blades are non-pitching, and have to perform well in a range of water speeds into a near-fixed speed load. An all-composite blade was designed to be mounted to a cast ductile iron hub. This new design had to improve upon the structural capabilities of the prior blade and enable economical volume fiberglass fabrication, while not sacrificing the previous efficiency. Extensive modelling and analysis were performed using multiple modified wind turbine codes on both the Gen4 design and evolving Gen5 designs. A further constraint was avoidance of cavitation, and a novel design methodology was used, resulting in a significant improvement.

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The blade designs were subjected to multiple independent computational fluid dynamics analyses, and ultimately the full rotor and turbine. The performance results also were compared with empirical Gen4 data from RITE in-water dynamometry.

The blade and its mounting component designs were also analyzed for static and fatigue stresses under the specified loads. The fabrication methodology for the new blade has been carefully coordinated throughout the design process to ensure an economical manufacturing process for initially low-volume, but increasing to high-volume production. Our blade fabrication partner, Energtx Composites of Holland, Michigan, was able to meet the initial costs and has the potential for achieving further cost reductions through evolving methodologies and volume production.

Turbine design As described earlier, the Gen5 is a ground-up design with regard to the use of custom components designed to optimize performance and reliability, and to provide economical volume production. Key Gen5 enhancements include: • composite (epoxy fiberglass) blades • cast iron hub and nacelle/pylon connection • integrated extreme-life drivetrain, including gearbox, shaft housing, bearings, lubrication, and seals • redundant dynamic (shaft) and static sealing • customized environmentally capable generator • failsafe brake • utility-grade data acquisition and control and supervisory control • non-toxic fouling-release coating system • manufacturing under a quality management system.

Several structural elements have been simplified and reduced in cost for volume production by replacing steel weldments with ductile iron castings. These include the rotor hub and the pylon to nacelle joint. Indeed, the main central nacelle section is a single casting that replaces a weldment of a steel tube and milled flange. Further, various minor components have been simplified.

The main drivetrain components of shaft, bearings, and gearing, along with the mechanical dynamic shaft sealing has been re-developed as a single integrated whole, drastically reducing the parts count and enabling improved geometry and cost-effective assembly. It also has permitted incorporating several ultra-reliability features designed to enable extended service intervals for the peculiar requirements of this kinetic hydropower service, including those related to gear and bearing lubrication and sealing.

The new generator is customized with regard to materials, treatments, and seals for added protection in our application.

The failsafe brake and associated electrical sensors and controls have been selected and implemented for maximum reliability, www.sname.org/sname/mt

The Gen5 KHPS 5 m turbine. The image on the right shows the unit’s internal components.

and are undergoing specific testing for the required performance and long-term reliability.

While fundamentally similar hydrodynamically to the Gen4 turbine, the Gen5 is shorter and more compact, while its initial default version has a higher power rating of 56 kW (actual power output depends on the characteristics of each site).

For the completed KHPS system, a failure modes and effects analysis (FMEA) has been developed, along with a “weakest link� analysis, both of which have informed the design to help optimize reliability and ensure structural safety.

The design is adaptable to varying mounting systems for deployment and installation in different sites.

The new commercially-focused mounting design is another key to reducing initial capital costs, and more importantly, to reducing the ongoing costs of O&M. The mounting of the turbines on the river bottom at RITE must be far more cost-effective than the monopiles drilled into the rock used for the demonstration phase. The cost of barges, tugs, cranes, and divers requires that a commercial deployment and mounting solution minimize the use of these on-water resources, both for initial installation and subsequent O&M activity costs.

The TriFrame is an example of a commercial mount developed for a range of site types. This hybrid (space-frame and gravity) mount holds three Gen5 turbines and can be deployed and retrieved with little or no diver intervention.

Gen5 testing In keeping with the market drive toward extreme reliability and certification, pre-production testing of the most critical components, as www.sname.org/sname/mt

determined by the FMEA, is essential. Accelerated lifetime tests using accurate simulations of real-world conditions are being performed with DOE support on the production version composite blade; gearbox dynamometry; mainshaft seal system; and the failsafe brake.

Blade testing has been performed in the NREL lab for static and lifetime (20-year) fatigue loads. Once the blade was successfully qualified, Verdant conducted successful in-water dynamometry testing of a complete full-scale Gen5 rotor at RITE in 2012.

Upon successful completion of these tests, the Gen5 turbines will be assembled and deployed in stages at the RITE project. The early stages will entail extensive commissioning testing of the

The Gen5 turbine has been designed based on custom components and designs and materials better suited to volume production. full systems, as well as mountings, cabling, interconnection, and supervisory array control. Also incorporated are retrievals and inspections in order to inform component wear models for the systems and verify the commercial maintenance model.

Environmental analysis and permitting Meeting the challenges of site assessment and permitting necessarily goes hand in hand with the technological advances, as water resource, power grid, and environmental issues are intertwined.

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The TriFrame mount for the RITE Gen5 turbines can be deployed and retrieved with little or no diver intervention.

The technology development has itself required enhanced resource measurements and analysis, involving the installation of specialized equipment in the river to make flow measurements that are needed in order to improve the computerized numerical modeling of blade, rotor, and turbine designs.

Securing the permissions necessary to install and operate turbines in the water and connect to the electric grid, is governed by a complex system of local, state, and federal regulatory agencies as well as the local community. This has been particularly challenging in a nascent field with many potential environmental questions and an evolving regulatory and compliance process.

For its Gen4 demonstration project with a multiple turbine array at its RITE site, Verdant received the first waiver of a FERC hydropower license, allowing connection of the generator turbines to the grid. This effort and the associated extensive environmental studies conducted in 2005-2008 allowed for an application to the FERC for a pilot license in 2010.

Under the FERC pilot project license received in 2012, and in coordination with New York State water quality certifications and other authorizations, the RITE project will be built out in a phased approach to include up to 30 turbines, on 10 TriFrames, generating up to 1 MW of power from the tides of the East River.

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To demonstrate environmental compatibility and secure the necessary permits to use the RITE East River waterway, a full range of environmental studies were done, at a cost of approximately $3 million. Environmental and related aspects studied have included: • Water quality • Benthic/bathymetry • Fish presence, abundance, species and behavior • Endangered Species Act species • Hydrodynamics • Avian • Underwater noise • Marine mammals • Electromagnetic fields (EMF) • Aesthetics • Recreation • Navigation and safety • Cultural, historic/archeological and tribal A number of these aspects are areas of continued study.

The initial studies answered many environmental questions regarding the operation of KHPS turbines at the RITE site. This has led to the implementation of advanced environmental monitoring plans to be executed over the course of the RITE project. www.sname.org/sname/mt

These continue to be a significant cost element (more than $2.5 million) of ongoing compliant operation under the FERC license.

Over the past several years of our monitoring and analysis, a high level of credibility has been developed with the regulatory agencies.

Major progress has been made in satisfying the concerns of regulators that the impacts of the technology are at most very small, and in growing confidence in our ability to detect any impacts if they were to occur. In the short term, this has resulted in success with permits for testing, and has also evolved into a longer-term plan to support the various permits needed as part of the new commercial FERC license.

Through evolving technology and increased understanding of potential impacts, monitoring has been refined and focused, with the result being a more manageable set of protocols. Working in consultation with federal and state natural resource agencies and project partners, we plan to execute a comprehensive set of environmental monitoring plans to observe various aquatic species throughout the phased development of the project. These plans are extensions of monitoring conducted during the Gen4 KHPS demonstrations, which showed no evidence of negative impacts to the East River environment.

A key regulatory advance is the increased use of adaptive management, whereby monitoring, reporting, and decision points are conducted at each stage of the multi-year buildout of the RITE Project.

Technological advances from Verdant’s work to ensure environmental compatibility include developing and implementing cost-effective environmental monitoring protocols. An example is the image included here from a video created by an aimable high-resolution sonar imaging system, showing a school of fish in the vicinity of an operating turbine passing unharmed outside of the rotating blades. The ever-growing library of such videos are effective at providing evidence that the turbines have very little or no effect on the fish.

This image, from a video created by a high-resolution sonar imaging system, shows a school of fish in the vicinity of an operating turbine passing unharmed outside of the rotating blades.

Learn More Much of the RITE project’s technical, environmental, and regulatory information is available on the project Web site at www.theriteproject.com including the submissions to FERC for the project’s pilot license.

Looking ahead

Acknowledgments

Regarding the scale-up of these systems, design work to date on the 10 m diameter-class turbine KHPS, with unit powers of 250 kW to 500 kW, indicates that the new design can also meet scalability requirements.

Market entry and regulatory requirements pose significant challenges, but the pace of advancement is hindered far more by the weak economic and financial environment than by any of the technical and permitting hurdles. As we expand our project development under the FERC license, we look to the RITE project not only to develop its own technology and deliver clean energy to New York residents, but also to anchor the development of a vital MHK industry in the United States. MT

The author wishes to thank Jonathan Colby and Mary Ann Adonizio of Verdant Power; Scott Hughes and Ye Li of the National Renewable Energy Laboratory; Joshua Paquette of Sandia National Labs; Fotis Sotiropoulos of the University of Minnesota-St. Anthony Falls Laboratory; Ken Workinger of Energtx Composites; and Kyle Wetzel of Wetzel Engineering. Their work forms much of the basis of this information. Major funding support for this work has been received from the New York State Energy Research and Development Authority and the U.S. Department of Energy.

Dean R. Corren is director of technology at Verdant Power, Inc. www.sname.org/sname/mt

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Evaluate, Assess, Develop How the Department of Energy’s Water Power Program is enabling MHK technology advancement

By Michael C. Reed

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Large photos show experimental wave tank tests of a point-absorber wave energy converter in an extreme sea state with wave heights of approximately 10 m. Inset photos depict corresponding computational fluid dynamics simulations of the wave energy device under the same conditions.

M

arine and hydrokinetic (MHK) systems refer to a set of technologies that use water as their motive force, or harness its thermal or chemical potential. These technologies offer the possibility of generating clean and predictable electricity from abundant, and as of yet, largely untapped ocean water resources. These resources include waves, currents (tidal, ocean and river), ocean thermal gradients (or ocean thermal energy conversion, or OTEC), and salinity gradients (or osmotic power). These emerging technologies are being actively considered as part of the “all of the above” strategy to help the United States, and the world, meet its clean energy goals.

The United States Department of Energ y’s (DOE) Water Power Program was established in 2008 as a result of the Energy Independence and Security Act (EISA) of 2007. Specifically, Section 632 of EISA defines the term “marine and hydrokinetic renewable energy” as electrical energy generated from: • waves, tides, and currents in oceans, estuaries, and tidal areas • free-flowing water in rivers, lakes, and streams • free-flowing water in man-made channels • differentials in ocean temperature (OTEC).

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EISA adds that marine and hydrokinetic renewable energy does not include energy from any source that uses a dam, diversionary structure, or impoundment for electric power purposes. Energy from water resources that employ dams and diversions fall within the Water Power Program’s hydropower portfolio, which is outside the scope of this article.

In addition to traditional hydropower technologies, the DOE’s Water Power Program is charged with evaluating the opportunities associated with MHK technologies, assessing their potential contribution to our nation’s energy mix, and undertaking the research and development needed to realize their full potential.

The opportunity MHK technologies are capable of capturing energy from a wide range of ocean resources.

These include: • waves, driven by prevailing winds, which are incident on every coastline and contain large amounts of concentrated energy potential • tidal currents, which ebb and flow twice a day through hundreds of inlets and estuaries due to the coupling of lunar gravitation with Earth’s axial rotation • ocean currents, which are the primary

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ocean water conveyors around the globe on a macro scale • river currents, from which downstream flow provides kinetic energy potential in many river systems without impoundments.

Another ocean resource, OTEC, taps into the temperature differential between the ocean’s warm surface waters (which are heated by solar radiation), and cold, deeper waters to generate power in a conventional heat engine. Ideal applications target a temperature differential of at least 20°C (36°F) in the first 1,000 m (approximately 3,300 ft.) below the surface.

And salinity gradient power, or osmotic power, uses the salinity difference in areas where high volumes of salt and fresh water mix. Two of the most practical methods being investigated are reverse electrodialysis and pressure-retarded osmosis. Both processes rely on the process of osmosis with ion specific membranes.

Our purpose here will be to focus on the DOE program’s principal areas of investment, which are wave and current energy. Due to limited funding, the perceived high cost of development, and limited resource accessibility for most of the U.S., the program is not currently investing in ocean thermal or osmotic power, but we continue to monitor global technological developments and deployments in these areas.

MHK resources are abundant and are most often in close proximity to highly populated coastal regions. This ready access may shorten potential transmission lengths to load centers while providing additional renewable energy options to regions with above average electricity costs (for example, Hawaii and Alaska). Furthermore, the technology is improving rapidly, and countries that have strong marine resources, such as the United States, Australia, Denmark, Ireland, Portugal, South Korea, Spain, and the United Kingdom are strongly committed to supporting the industry. Growing international interest in MHK technologies is further represented by the fact that 20 countries are (54) marine technology July 2013

Artist’s rendering of an open-water, fully energetic, multi-berth test center. Image courtesy BCS, Incorporated.

now members of the International Energy Agency Ocean Energy Systems (OES) executive committee. The OES implementing agreement mission is to facilitate and coordinate ocean energy research, development, and demonstration through international cooperation and information exchange, leading to the deployment and commercialization of sustainable, efficient, reliable, cost-competitive, and environmentally sound ocean energy technologies.

In spite of this strong interest and the potential benefits and inherent advantages of MHK, technology developers are faced with many challenges. The Water Power Program seeks to address these challenges and advance the technical readiness of these technologies in the hopes of achieving the full potential that MHK systems offer through a variety of federal level investments. These investments seek to catalyze private sector innovation, apply the core competencies and capabilities of our national laboratory infrastructure, and

partner with other federal agencies to lower the cost and speed the commercialization of these innovative technologies.

Resource assessments To comprehensively assess the opportunity of MHK for the United States, the program undertook a series of resource assessments in the areas of wave energy, tidal current energy; ocean current energy; river current energy; and ocean thermal energy. The full reports of the assessments can be found at http:// water.energy.gov/resource_assessment_ characterization.html.

In addition to confirming the potential of these resources, the assessments have served to inform the program’s investment strategy in in two ways. First, considering the significance of the overall wave resource, the program is going to prioritize wave energy converter (WEC) technology development.

Secondly, considering the advanced stage of technology readiness and cost www.sname.org/sname/mt

opportunities of tidal energy technologies, the program will continue to invest in tidal energy technologies as they present the best early market opportunities.

Building on the recently completed resource assessments, the program is currently performing in-depth technical and economic studies and analyses of MHK technologies. This work includes technical evaluations and testing to determine device performance, opportunities for design optimization and cost reduction, and consideration of the costs associated with installation and operation. In 2010, the program invested $37 million in 26 different MHK projects across a wide range of technology readiness levels and all but one of these projects will be completed in 2013.

The studies and analyses also include analysis of the costs associated with permitting, environmental effects mitigation, site development, and other non-technical issues that contribute to MHK development and deployment costs.

The results of these studies and analyses will ultimately enable the program to identify the technologies that have the highest likelihood of success, and to predict current and future costs of energy from these leading devices. This information, along with the program’s research and development (R&D) agenda to support technology advancement and commercialization, will be presented in a report to congress at the end of the current fiscal year. This report is considered a significant milestone for the program, and represents the culmination of the program’s initial investments and analytical efforts since being established in 2008.

The recently released FY 2014 budget request represents the administration’s highest funding request ever ($55 million) for the Water Power Program. This request maintains a solid trend of consistent funding for MHK. Furthermore, the program has benefited from strong bipartisan congressional support. As a result, the program has been able to pursue numerous initiatives that support technology www.sname.org/sname/mt

development—through industry demonstration efforts, laboratory based science, and modeling and simulation activities— while simultaneously supporting market acceleration and deployment initiatives.

The Water Power Program is pursuing a robust and aggressive portfolio of projects and initiatives aimed at assessing MHK’s potential contribution to our nation’s energy mix. These activities can be categorized into four key thrust areas.

TECHNOLOGY ADVANCEMENT AND DEMONSTRATION. This will involve leading the development of high-impact, levelized cost of energy (LCOE)-reducing technologies. The program plans to support the demonstration and deployment of innovative MHK systems in U.S. waters in the most rapid and responsible manner possible.

Multiple technologies, across vastly different water power resources, are needed to achieve domestic water power deployment goals of 23 GW by 2030. The program’s strategy is to support high-risk, high-impact R&D efforts needed to drive innovation that will overcome the technical and cost challenges that the current generation of devices face.

Specific efforts supporting this objective include a $13 million, cost-shared funding opportunity announcement (FOA) for MHK system performance advancement, which was announced in April 2013. These investments seek to advance technology performance of existing marine and hydrokinetic systems through the development and application of innovative components that are designed and built specifically for MHK applications. This FOA will focus on improving the cost competitiveness of systems already in development, with the goal of advancing the technology performance of these systems.

Another effort supporting the objective is small business innovation research (SBIR).

The program continues to make annual investments through the SBIR program to spur innovation from the small business sector.

It is advantageous that the Water Power and Wind Power Programs are within a single

To test and optimize earlystage technologies, developers need a series of appropriately-sized test facilities that can accommodate devices throughout the entire technology readiness scale. office at DOE. This alignment enables the Water Power Program to effectively apply to MHK technologies and systems the lessons learned in the wind industry. For example, we are already considering array effects and grid connectivity, transmission, and integration issues. These challenges are already being addressing by the department’s Wind Program. Investments in other critical technology development issues (array connectivity, marinization, and so forth) can be cost shared with offshore wind investments as well, effectively speeding development and lowering costs to each program element and to industry as a whole.

TESTING INFRASTRUCTURE AND INSTRUMENTATION. This will involve accelerating and reducing the costs of commercialization. To test and optimize early-stage technologies, developers need a series of appropriately-sized test facilities that can accommodate devices throughout the entire technology readiness scale. Lacking this infrastructure, developers don’t have a choice other than to prematurely test their devices in harsh, open-water conditions; and July 2013 marine technology

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usually at device scales that don’t match the energetic levels of open water, nor in an environment that can be systematically repeated.

Further, this independent open-water testing is extremely costly and time consuming.

The program is committed to building out a robust test infrastructure that will cost effectively and expeditiously enable developers to thoroughly and repeatedly test devices in appropriate test environments. For wave energy devices, this includes the development of two key test facilities. The first is a controlled condition, deep-water wave test tank that can overcome the depth limitations of existing wave tanks, and which can generate and test 1/10 to 1/2 scale WECs with appropriately sized normal and rogue waves.

The second is an open-water, fully energetic, multi-berth test center. As a critical first step, DOE intends to fund two university- or national laboratory-led projects that will conduct preliminary engineering designs and select a potential site for an open-water, fully energetic testing facility for wave energy technologies. The goal of this opportunity is to identify a site location and a recommended construct for a national wave test facility. A notice of intent to fund design and site selection for this critical infrastructure element was issued in April 2013.

Given the nascent stage of the industry, it is essential that we learn as much as possible from our limited deployment opportunities.

This is only achievable through extensive instrumentation of both devices and the surrounding marine environment. To support this data collection, the program is developing a standard instrumentation package that will be made available to industry to collect the data necessary to monitor performance and impacts, advance the knowledgebase of stakeholders, and efficiently speed progress to the next design iteration.

The U.S. also is actively engaged as a key participant in the International Electrotechnical Commission (IEC) Technical Committee 114 (TC 114), which is developing and maintaining technical specifications and standards for wave, current, tidal, and (56) marine technology July 2013

Bay of Fundy Puget Sound

San Francisco Bay Cape Cod and Long Island

Mean Kinetic Power Density LOW

HIGH

Alaska

ocean thermal energy resource characterization and conversion device performance assessment. With 22 member countries, U.S. participation on TC 114 serves to ensure that U.S.-vested interests are considered during standards development, and to alert the U.S. MHK community of trends, best practices, and global progress in the development and implementation of MHK technologies. Our involvement ensures that the U.S. efforts in wide ranging activities to support MHK technology are supported by the standards that will guide and oversee the industry.

In the area of modeling and simulation, the goal is to compress device design cycles and transparently identify LCOE reduction opportunities. The program’s strategy is to

Alaska contains the largest number of tidal energy locations with high kinetic power density, followed

by Maine, Washington, Oregon, California, New Hampshire, Massachusetts, New York, New Jersey, North and South Carolina, Georgia, and Florida.

provide industry with open-source computational tools for simulation of device designs and device performance in both operational and extreme conditions, as well as simulation of device array designs and array impacts on their marine surroundings. Developing opensource advanced design tools supports MHK technology advancement by accelerating device design evolution and array optimization, therefore reducing costs to developers.

Computational device design tools are an efficient and cost-effective means of comparing device designs in terms of power production, device reliability, and device survivability in extreme conditions. Accurate, predictive design tools will enable developers to shave off costs if they are able to reduce safety www.sname.org/sname/mt

WIND & WATER POWER PROGRAM

devices deployed in extreme conditions and in utility-scale arrays.

• Tidal and current tools validation. The program will provide verified open-source tools for the design of river, tidal, and ocean current turbines. These tools will help reduce LCOE, improve reliability, and reduce deployment barriers. These efforts will include code development, verification and ongoing validation against physical test data, and the establishment of an international cooperative test and code verification program to support direct comparison of model results from test facility to test facility around the world.

Annual Wave Power Density LOW

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Alaska

The total available U.S. wave energy resource is estimated at 2,640 TWh/year. Given the limits of device arrays, approximately 1,170 TWh/year of the total resource is theoretically recoverable.

margins built into the design to account for uncertainties. Similarly, computational tools for simulating MHK device arrays enable multiple configurations to be tested for power performance, shadowing effects, and impacts to the surrounding marine environs without the need for costly deployments or tank tests.

The three major components of this computational and design tools effort are as follows.

• W ave energ y conver ter si mu lat ion (WEC Sim). The WEC-Sim project aims to develop a freely-available, quickrunning, open-source computer code to assess energ y capture and power www.sname.org/sname/mt

performance of various wave energ y converters for use by device developers to advance TRL 3-4 designs or increase power performance of TRL 5-7 designs, and by researchers to advance state-ofthe-art WEC modeling tools.

• WEC extreme conditions and array modeling. Understanding WEC reliability and survivability in extreme (storm) wave conditions and WEC behavior and performance when deployed in arrays is a future but significant industry need. This effort requires moving beyond current analyses of single-wave energy converters functioning in standard operating (non extreme) wave conditions and will result in improved device reliability and lower O&M costs for

M A R K E T A C C E L E R AT I O N A N D DEPLOYMENT (MA&D). This will involve removing critical path barriers for cost-effective access to high-resource areas. This thrust area aims to minimize key risks to deployment to reduce the cost and time associated with permitting MHK projects. The program’s MA&D work focuses on addressing non-technical barriers to the development, deployment, and evaluation of these systems. This includes undertaking research and developing tools to identify, mitigate, and prioritize environmental risks; providing data to accelerate permitting timeframes and drive down costs; increasing education opportunities for next-generation MHK scientists; and engaging in ocean planning to ensure that MHK is considered in the nation’s marine spatial plans.

In 2012, the MA&D team conducted a rigorous analysis to identify the greatest MHK environmental needs; identify gaps remaining from previous efforts; rank those gaps; and develop a plan to strategically reduce environmental barriers to deployment. The strategic plan for MHK MA&D work between 2013 and 2020 focuses on the following three thrust area elements.

• D ata collection and experimentation efforts will use laboratory experimentation, field monitoring of installations, and the development of predictive models to systematically gather data on two major sub-elements: effects on aquatic organisms July 2013 marine technology

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and effects on physical systems.

• The development of monitoring and mitigation technologies and techniques will help to ensure that data can be collected successfully and cost effectively, and that industry and regulators have mitigation options at their disposal where necessary to enable continued development in a sustainable manner.

• Information sharing and international collaboration will complement the first two elements by ensuring that research data collected throughout the world is aggregated, analyzed, and shared. These activities will help magnify the value of individual data collection activities; draw information and lessons learned into the United States from abroad; and guarantee that all interested parties have access to the current state of scientific understanding of MHK environmental impacts.

These efforts are aligned to strategically reduce environmental uncertainty, and subsequently lower permitting time and costs for MHK projects. They will do this by focusing resources on areas of concern, providing tools and techniques for data collection, and ensuring that data is available and synthesized so that it can benefit the industry as a whole.

RESOURCE CHARACTERIZATION. This is a prime driver for reducing the LCOE of any renewable resource and for reducing risks in MHK device deployment. Proper resource characterization occurs at multiple space and time scales, from national scale resource assessments of total energy available annually to characterizing the extent of variability of mean tidal current speeds and turbulence across a strait over a period of minutes. This understanding and knowledge are important in determining siting of MHK devices. The program’s role in this arena includes performing national scale resource assessments (as outlined previously); developing models and tools for resource characterization; and fostering research into physical phenomena that determine resource characteristics. It also (58) marine technology July 2013

Multiple technologies, across vastly different water power resources, are needed to achieve domestic water power deployment goals of 23 GW by 2030. includes developing methodology and best practices for resource characterization at smaller spatial scales and distribution of data resulting from resource characterization initiatives.

A request for information (RFI) by the Wind and Water Power Technologies Office regarding future beneficial activities and strategic partnerships in the area of resource characterization was completed in October 2012. The RFI sought stakeholder input on wave and tidal resource information needs, and responses to the RFI from the wider marine and hydrokinetic energy community were used to inform the Water Power Program’s resource characterization strategy, as detailed in that thrust area element and sub-element sections.

Public-private partnership There is little doubt that federal investment in the development of new technologies is oftentimes essential to spur innovation, and the Department of Energy has often performed

critical enabling roles with a wide range of leading-edge technologies. The Water Power Program expects to play a similar partnership role with MHK technology developers and other stakeholders to support the timely development and demonstration of these innovative technologies. We are supporting the underpinning research, development, test and evaluation efforts necessary to prove out the promise of these emerging technologies, both domestically as yet another renewable energy option, and to position U.S. industry at the forefront of this global opportunity.

The promise of MHK will only be realized by an effective public-private partnership that taps into our nation’s unrivaled capacity for innovation and entrepreneurial spirit.

These are exciting times for this industry, and the Water Power Program is committed to helping MHK realize its full potential. MT Michael C. Reed is program manager/chief engineer for the Water Power Technologies Program at the United States Department of Energy.

Learn More

For further information on the DOE’s Water Power Program, go to http://water.energy.gov/about.html For further information on the International Energy Agency Ocean Energy Systems Executive Committee, go to http://www.ocean-energy-systems.org/

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Sustainability in the Maritime Industry: A Collection of Relevant Papers Edited by Richard Delpizzo, Haifeng Wang, and Andrew Panek

www.sname.org Tommie-Anne Faix at tfaix@sname.org www.sname.org/sname/mt

ISBN 978-0-939773-87-9 July 2013 marine technology

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The Utility Perspective:

Puget Sound Snohomish County Public Utility District and tidal energy

By Neil Neroutsos After more than six years of study, the Snohomish County Public Utility District (PUD), north of Seattle, Washington, expects to receive approval this summer from the Federal Energy Regulatory Commission (FERC) for its pilot tidal energy project in Admiralty Inlet in northern Puget Sound. The project will deploy two turbines, each with a diameter of 6 m, designed by the Irish firm OpenHydro, at a depth of about 58 m. The PUD expects to launch its pilot as soon as fall 2014, operating the turbines for a period of three to five years.

“Tidal energy is a renewable, locally-generated resource that can be easily and efficiently integrated into our electrical grid,” says PUD General Manager Steve Klein. “This project will help identify whether this resource can provide long-term environmental benefits to the citizens of the Northwest.”

The project site offers attractive features, including swift currents, good access from nearby ports, a rocky seabed floor with little sediment and vegetation, and proximity to grid connections. Admiralty Inlet is a large body of water, which makes the footprint small by comparison and helps minimize project impacts.

Extensive study The PUD has partnered with a broad range of technical partners to assess the viability of the site. As a result of the utility’s research, Admiralty Inlet is one of the most thoroughly characterized tidal energy sites in the world. Studies have obtained environmental baseline data, tidal current profiles, bathymetric data, and geophysical information. Researchers also have (60) marine technology July 2013

addressed issues related to grid interconnections and navigational traffic.

Additional studies have covered the pilot project’s design, operation, monitoring plans, and biological assessments. During its public process, the utility engaged numerous stakeholders, including local, state, and federal agencies; tribal groups; business and environmental organizations; and residents. The utility has held more than 100 meetings with interested groups to share information and build consensus around the project.

“Puget Sound is an inland sea completely surrounded by committees,” jokes Craig Collar, PUD assistant general manager of power supply, who has led the project since its early stages. “Initially we were introducing a project that people knew very little about. Once you mention a turbine with spinning rotors, many people automatically jump to conventional hydropower, which is a completely different animal. So we did quite a bit of education.”

FERC developed its hydrokinetic pilot plant licensing process specifically for projects such as the PUD’s Admiralty Inlet pilot. The formal (continued on page 62) www.sname.org/sname/mt

The Utility Perspective:

Hawaii

Hawaiian Electric and ocean renewable technologies

By Arthur Seki and Stephen Luckett Hawaii depends on oil for nearly 90% of its primary energy, more than any other state in the nation. Crude oil imported to Hawaii is refined for aviation fuel and gasoline and diesel for ground and sea transportation, with the sludge-like residual fuel oil left to generate electricity.

This dependency worked well while oil remained relatively inexpensive and plentiful. However, it is no longer sustainable. Oil dependency threatens Hawaii in several ways: • energy security (because oil tankers must travel thousands of miles from the Middle East, Russia, or Southeast Asia) • economy (as oil prices have increased and become more volatile) • local and global environment (as Hawaii has a lot to lose from rising sea level and the extreme weather of global climate change).

The price of imported products has long been high in Hawaii, the most remote island chain on earth.

Some call it the “paradise tax.” However, in the last two years, electricity prices have risen to new heights and are staying there.

The meltdown at the Fukushima Dai-Ichi nuclear reactor after the devastating earthquake and tsunami of March 2011 led Japan to shut down its fleet of 50 nuclear plants, which supplied a quarter to a third of its electricity.

Japan reopened mothballed power plants and ramped up purchases of the same fuel oil that Hawaii uses for www.sname.org/sname/mt

most electrical generation. Hawaii is in the Asia-Pacific fuel market and must pay the going rate in that market.

Even as Japan restarts a few nuclear plants, fuel oil prices will be high in Hawaii for some time to come.

Hawaiian Electric has sought to increase renewable energy since the 1980s. In 2008, the utility joined the governor of Hawaii and the United States Department of Energy (DOE) in a clean energy agreement. Its goal is that 70% of Hawaii’s energy for ground transportation and electricity will come from clean sources by 2030, specifically 30% through energy efficiency and 40% through increased renewable energy.

Hawaii’s renewable resources are bountiful. Sun and wind are strong. Fallow sugar and pineapple lands can grow biomass and biofuel crops. Plentiful refuse can be burned to generate electricity, keeping it out of overflowing landfills. Volcanic activity on Hawaii island, and perhaps Maui, has huge geothermal energy. The emerging smart grid and electric vehicles also have a role in a clean energy future.

And in every direction one looks is the ocean, which has long held the promise, so far unfulfilled, of providing the islands a significant part (continued on page 63) July 2013 marine technology

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Puget Sound The sea spider, a monitoring device deployed here by University of Washington researchers, measures factors such as water velocity, temperature, depth, dissolved oxygen, and underwater noise.

licensing process, traditionally used for much larger hydroelectric projects, would have been extremely extensive and expensive; it is better suited for projects of 30 to 50 years. Given that the PUD’s project has a lifetime of less than five years and limited generation, FERC recognized that a pilot licensing process would facilitate the PUD’s needs in testing a marine energy technology.

The PUD’s partners include the University of Washington, the Electric Power Research Institute, the Pacific Northwest National Laboratory, and the National Renewable Energy Laboratory. The utility has secured more than $12 million for research and development from the Department of Energy, the Bonneville Power Administration, and other federal appropriations.

While the pilot project has garnered considerable support and attention, it hasn’t been without its share of challenges.

Concerns were raised, for example, about southern resident killer whales, or orcas, which travel through the area. A study by the Sandia and Pacific Northwest National Labs concluded that, even in the unlikely event of orcas coming in contact with a turbine that “it would not be likely to experience significant tissue damage” and, at worst, a minor bruising. In fact, orcas rarely spend time deeper than 30 m; the top of the turbine would sit 45 m below the surface, or 15 m deeper than orcas typically dive.

Meanwhile, a Japanese telecommunications firm with a cable that runs along the seabed of Puget Sound raised concerns that the tidal project’s installation, operation or removal (62) marine technology July 2013

could damage its cable. The PUD modified its plan so that the two turbines will be placed 170 and 238 m away from the cable.

During past deployments at other sites, OpenHydro has demonstrated exceptional accuracy, with deployments to within 3 m of the intended target. To further minimize hazards, the PUD

As a result of the utility’s research, Admiralty Inlet is one of the most thoroughly characterized tidal energy sites in the world. has committed to a live boat deployment and recovery method, which ensures that no anchors will be used, thus negating any threat of dragging them across the cable. In its environmental assessment, FERC approved of the measures noting they would minimize any potential harm to the cable operator.

Environmental design features The tidal turbine’s design incorporates several features that prevent or minimize other potential environmental risks, including • no requirements for oils, greases, or other lubricating fluids • rotor blade tips that are retained within the outer housing (continued on page 64) www.sname.org/sname/mt

The Utility Perspective:

HAWAII

of their energy needs. Currently, three technologies hold the most promise: seawater air conditioning, wave energy, and ocean thermal energy conversion.

Seawater air conditioning. Since 2006, Honolulu Seawater Air Conditioning (HSWAC) has worked to bring district cooling using deep-sea water to downtown Honolulu. Hawaiian Electric was among the first to sign up and has encouraged downtown customers to be among the 40 downtown buildings planned for the project. It aims to displace approximately 17 WM of electric

The price of imported products has long been high in Hawaii, the most remote island chain on earth. Some call it the “paradise tax.” demand, save millions of gallons of potable water, and avoid dumping millions of gallons of chemicals into the municipal sewage system.

HSWAC’s development team brings broad experience of seawater cooling from Stockholm and Amsterdam. It is collaborating with Makai Ocean Engineering, a Hawaii-based firm that is a leader in deep sea-to-shore pipelines, having installed systems in Toronto and at Cornell University.

Financing challenges and the lengthy engineering and permitting process have delayed the project, but progress continues slowly. A separate local start up, Kaiuli Energy, is exploring prospects for seawater air conditioning in Waikiki, where hotel, restaurant, retail, and residential air conditioning represent a major part of energy use.

Wave energy. Hawaii is the birthplace of surfing, and everyone who stands at a shore break knows the power of the waves. Turning wave energy into a utility-scale electricity source remains an enticing but elusive goal.

The Electrical Power Research Institute’s 2011 technical report, Mapping and Assessment of the United States Ocean Wave Energy Resource, estimated the country’s total theoretical wave resource at 1,170 TW hours per year, with 80 TW hours per year around Hawaii, more than the Gulf of Mexico and Puerto Rico.

The potential was recognized in 2009 with the formation of the Hawaii National Marine Renewable Energy Center, based at www.sname.org/sname/mt

the University of Hawaii, with funds from the Energy Efficiency & Renewable Energy Office of the DOE. Its manager, Dr. Luis A. Vega, is a long-standing expert and champion for ocean energy.

Wave device developers such as Ocean Power Technology have used waters off Kaneohe Marine Base Hawaii, on Oahu’s windward shore, as a test site with funding from the Office of Naval Research. Vega and his colleagues are working to expand the wave energy test site off Kaneohe with the support of the United States Navy and the DOE to make it attractive to more ocean energy developers.

Ocean thermal energy conversion. Popularly called OTEC, this process takes advantage of temperature differences between the warmer, top ocean layer and colder, deep water to generate electricity. OTEC is firm (24/7) power, a clean energy source, environmentally sustainable, and would not compete for precious resources in Hawaii like land or fresh water. One of two major OTEC systems leaves fresh water as a by-product of energy generation.

Many energy experts believe that, if OTEC can be proved cost-competitive at utility scale, it could produce billions of watts of electrical power. For Hawaii, it would be a major game changer. (continued on page 65)

A 210 kW OC-OTEC experimental apparatus (1993–1998) at the Natural Energy Laboratory Authority of Hawaii. Photo courtesy Hawaii Natural Energy Institute, University of Hawaii.

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The Utility Perspective:

Puget Sound

• slow rotational speed • c avitation prevention due to deployment depth and turbine design • full submersion of the device • g ravity platform for device so no drilling, piling, or pinning required • device and foundation that are capable of being fully relocated or removed.

The PUD and OpenHydro have worked with design engineering firms to create a foundation for the turbines using conservative assumptions about seabed composition. Its design ensures it can withstand strong tidal forces expected to be found within Admiralty Inlet. As part of its monitoring plan, the PUD will employ a remotely operated vehicle to track any scouring around the foundation, and sensors mounted onto the foundation will detect any vibration or settlement of the foundation. These sensors will be constantly monitored to enable the PUD to detect any unexpected issues after installation.

“Most importantly, this multi-year project will answer long-standing environmental questions about tidal energy and demonstrate environmental monitoring technologies that could enable sustainable commercialization of all marine renewable

technologies, including tidal, wave, and offshore wind,” says Dr. Brian Polagye, a key member of the project team and faculty member in the University of Washington’s Mechanical Engineering department.

While the amount of power generated from this project is expected to be modest, the PUD stresses that the pilot’s main intent is not energy generation for its customers. Rather, it aims to study, monitor, and evaluate the environmental, economic, and societal effects of hydrokinetic (continued on page 66) This turbine image shows the underwater monitoring package (left side of turbine) that the PUD will use as part of its pilot project. Image courtesy OpenHydro.

Irish turbine manufacturer OpenHydro installs a device in the Bay of Fundy in Nova Scotia. Image courtesy OpenHydro.

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The Utility Perspective:

HAWAII

There are some 98 nations with adequate OTEC resources. Image source: Hawaii National Marine Renewable Energy Center.

The first OTEC demonstration plant was built in Cuba in the 1930s. The federal government became actively involved in 1974 and conducted OTEC-related tests and studies at the Natural Energy Laboratory of Hawaii Authority (NELHA) at Keahole Point on the Kona coast of Hawaii Island to develop a modern OTEC plant.

Over the following decade, a barge dubbed Mini-OTEC, anchored off Keahole Point, demonstrated production of net electrical power via the new closed-cycle OTEC technology. In 1981, shore-based OTEC research began with a project testing biofouling and corrosion counter measures for the closed-cycle OTEC process.

From 1993 to 1998, the 210 kW OC-OTEC experimental apparatus was operated at NELHA to continue the search for valuable data and future modifications to improve the ocean thermal conversion process.

Ultimately, OTEC suffered the fate of many renewable technologies, as the oil exporting countries increased output and reduced prices to the point that most renewables became economically prohibitive. At today’s high oil prices, however, a range of companies—from small, academically-based startups to industrial giants like Lockheed Martin—are reviving interest in OTEC. Hawaiian Electric is negotiating a power purchase agreement (PPA) with a small OTEC company. It is not a final contract, but an indication of commitment and the faith of the utility that the project offers a reasonable chance of success. A PPA provides firm documentation of a customer for the developer’s generation output, an essential element in seeking investors and other funding for the development process, which includes community outreach, environmental assessment, and permitting. www.sname.org/sname/mt

On the most remote island chain in the world, Hawaii’s people feel a deep attachment, reverence, and concern for the ocean. Descendants of the first Polynesian navigators, who arrived here hundreds of years ago navigating by the stars, often have familial attachments to specific coastal areas and consider marine animals, especially sharks, to be protective personal deities, or “aumakua” in Hawaiian.

Hawaii is home to significant academic and commercial research and development in the ocean sciences—the University of Hawaii being somewhat uniquely a land grant, sea grant, and space grant academic institution—and a number of commercial industries depend on the ocean. Hawaii’s tourism

Vega and his colleagues are working to expand the wave energy test site off Kaneohe with the support of the United States Navy and the DOE. industry, the state’s largest, views a clean ocean, bright beaches, and swimmable waters as an essential part of Hawaii’s attraction to the six to seven million people who visit each year. The proprietary emotions that Hawaii’s surfing and boating community feel toward the ocean cannot be measured.

Ocean projects (most recently a high-speed interisland ferry that held great economic promise) have failed abruptly for lack of community support and adequate environmental assurances as foundation for that support. A thorough and unbiased environmental study and (continued on page 66) July 2013 marine technology

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The Utility Perspective:

The Utility Perspective:

Puget Sound

energy. Information collected will be used to support the decision making process for any longer-term approaches regarding future energy projects in Washington waters.

The pilot will rely on an adaptive management approach to maintain a continuous dialogue with stakeholders regarding the results of environmental monitoring. These results, in combination with other data about the Puget Sound’s ecosystem, will help researchers make any necessary adjustments to the pilot project during its operation. “There is no single resource we can secure to solve all our energy needs,” says Stave Klein. “It has to be a combination, and there’s virtually no renewable resource we won’t consider.” MT Neil Neroutsos is media liaison for Snohomish County Public Utility District in Everett, Washington.

Turbine Details Each of the devices consists of a 6-m open-center turbine with a triangular base constructed of 2-m diameter steel tubing. In total, the structure with the turbine affixed is roughly 13 m tall and weighs approximately 275 tons. The turbines have a combined nameplate capacity of 600 kW. Each device consists of a horizontal axis rotor with a single moving part and power takeoff through a direct drive, permanent magnet generator. It is comprised principally of the rotor and the stator, which are an assembly of structural steel, fiberglass, and electrical components.

Each turbine will be equipped with fixed instrumentation for monitoring, including doppler current profilers to characterize turbine inflow conditions and other measures; broadband hydrophones to monitor turbine noise and marine mammal vocalizations; and performance sensors to monitor voltage/ current, rotor rotational rate, vibration, and other measures.

A recoverable adaptive monitoring package (AMP), among other things, will include • a stereo imaging system to monitor the turbine rotor and track fish and marine mammal interactions • water quality measurements to study dissolved oxygen levels • click detectors to monitor marine mammal activity (primarily the harbor porpoise) • fish tag receivers to track presence of tagged fish in the area.

The AMP is being designed to enable new instruments to be incorporated into the monitoring plan, as needed, over time as the pilot project progresses.

HAWAII

community outreach will be as essential to a successful OTEC project as solving the many technical issues.

Makai Ocean Engineering is again deeply involved, as it was from OTEC’s beginnings, assisting the United States Navy with plans to procure, install and operate a 100-kW turbine generator for the Hawaii Ocean Thermal Energy Conversion Test Facility at NELHA. Lockheed Martin is developing OTEC heat exchangers and cold water pipes, with the ultimate goal of large-scale commercialization.

Meanwhile, OTEC International, a Maryland company, is in the process of constructing and operating a 1 MW, shore-based OTEC innovation and demonstration facility at the Hawaii Science and Technology Park (also at NELHA).

All involved believe demonstration of OTEC-generated electric power will help spur the commercially-funded technology development needed for large-scale expansion.

Dr. Vega and his colleagues will tell anyone who listens that their research shows 98 nations with adequate OTEC resources within their exclusive economic zones for extractable energy production, which could equal more than half of worldwide energy consumption. However, except for the U.S., France, Japan, Taiwan, and China, none of the other nations appear to be interested in expending the research and development resources needed to explore this potential.

The hope that zealous OTEC proponents still hold for this promising technology must be tempered by the reality that it may not happen until the federal government or some other source provides substantial support for research and development, demonstration, and testing to bring it to commercial application.

The LNG bridge Hawaiian Electric and the state of Hawaii are close to a formal decision to convert from oil to natural gas to general electricity as a bridge to more renewables in the future.

Bringing liquefied natural gas (LNG) to Hawaii would require diverse marine engineering. A shortage of available land around Kalaeloa (Barbers Point) Harbor near Oahu’s main power plants could require near-shore floating storage and regasification structures to hold and process LNG brought to Hawaii in small-scale LNG carriers. Taking advantage of the low natural gas prices available on the U.S. mainland will require cost-effective means of transporting it over 2,000 miles of ocean. MT Arthur Seki is director of the Renewable Technology Division for Hawaiian Electric Company. Stephen Luckett is senior energy specialist of the Renewable Technology Division for Hawaiian Electric Company.

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www.sname.org/sname/mt

&R T Bulletin 6-2

MVEP EE-1

Marine Vessel Environmental Performance Assessment Guide Energy Efficiency: Hull and Propeller Operations and Maintenance Technical and Research Program

The Society of Naval Architects and Marine Engineers 601 Pavonia Avenue, Jersey City, NJ 07306 www.sname.org

This guide discusses three main areas that relate to measuring and improving the energy efficiency of the hull and propeller in operations and maintenance. Hull and propeller condition have a significant impact on fuel efficiency of ocean going vessels. The bulletin describes best practices in hull and propeller maintenance and treatments to ensure vessels maintain highest fuel efficiency possible in today’s market of high fuel costs and legislative demands for the maritime industry to reduce emission and improve efficiency. It is the first in a series being developed to address vessel environmental performance.

Technical and Research Bulletin 6-2 MVEP EE-1 is a 25-page report issued electronically. It may be ordered through the SNAME web site (http://www.sname.org/SNAME/Go.aspx?c=ViewDocument&Do cumentKey=ded3b7b0-d044-44c9-ac1f-45a1840f8b03) or by contacting Tommie-Anne Faix (tfaix@sname.org or 201-499-5068) for $40 ($20 for SNAME members). www.sname.org/sname/mt

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In February 2011, a 1/4.5 scale v3.1 Columbia Power WEC prototype was deployed for thirteen months of sea trials in Puget Sound.

Validating the Wave Energy Model Columbia Power’s development work with StingRAY By the engineering team at Columbia Power Technologies

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www.sname.org/sname/mt

he future direction of the energy supply in the united states is dominated by a number of important themes: decreasing our reliance on carbon-based resources; improving our energy and national security; ensuring our economic competitiveness; and promoting economic development through the growth of new technology-driven industries. Renewable energy resources, predominately wind and solar, are increasingly viewed as one solution for meeting these goals. However, these alone are not sufficient to meet the nation’s needs. Adding new renewable energy resources, such as wave energy, provides more stability to our energy portfolio and the opportunity to strategically replace many legacy, base-load energy resources, while ensuring sufficient capacity is available to meet growing demand.

The ocean is an attractive energy source because it behaves like a great flywheel as it captures energy from the winds blowing across its surface. The resulting stored energy is delivered in swells that travel hundreds and even thousands of miles before crashing on the shore.

And while seasonal in energy delivered, wave energy is clean, abundant, predictable, and consistent. The U.S. Department of Energy estimates wave energy has the potential to power over 100 million homes in the U.S. each year.

The idea of using the vast amount of energy in ocean waves is timeless. Over the past halfcentury, more than 1,000 patents have been filed around the globe for various wave energy conversion systems and components. In spite of this, only a handful of companies have actually demonstrated power production in sea trials. The problem—primarily one of survival in a range of operating conditions that spans three orders of magnitude during a typical calendar year—is further complicated by the economic demand for cost-competitive energy production. In order to deliver a commercially viable design, the risks associated with these requirements must be evaluated with technoeconomic models. These models are intended to progressively reduce uncertainties.

Columbia Power’s product development efforts over the past seven years have focused

www.sname.org/sname/mt

on modeling the wave energy converter (WEC) as a fully-coupled system and validating the model through a series of scaled physical experiments. We strive to reduce uncertainty and risk by conducting the experiments in the lowest cost, smallest scale, and most controllable environment necessary for the technology readiness level under consideration.

At a high level, the Columbia Power wave energy conversion process includes a series of steps, starting with the hydrodynamic-tomechanical transfer of energy to a slow-speed, high-torque electric generator that produces stochastically-variable power output proportional to the incoming wave power. This power is conditioned to stable, electric grid-compatible output through the use of power electronics and DC bus energy storage.

Our current WEC design, the StingRAY, is hydrodynamically optimized with a tri-member fiber-reinforced polymer hull and two hightorque, extremely low-speed, large-diameter direct-drive rotary generators. The device has three moving bodies: a central body and two floats. The central body (nacelle/dual spar) is attached to the forward and aft floats through drive shafts along its central longitudinal axis.

A significant departure from conventional highspeed, steady state electrical generation, two power-take-off (PTO) generators contained

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Validating the Wave Energy Model

within the nacelle convert the low-speed reciprocating rotary motion into electricity. The WEC captures power through two absorption modes: relative pitch between the central body and forward float, as well as relative pitch between the central body and aft float. Thus, all three bodies share the same heave and surge degrees of freedom, while each body experiences its own pitch response, resulting in five degrees of freedom affecting the power absorption modes.

Experimental testing Deployment and testing of commercial-scale prototypes is an expensive and necessary milestone, and only likely to be funded if appropriately de-risked in advance. Though much has been learned from the offshore oil and gas industry about long-term operation of platforms at sea, the necessarily dynamic nature of wave energy conversion devices presents even more complex modeling scenarios and challenging design requirements. The growing offshore wind industry also provides relevant and useful learning for wave energy conversion technology.

Whether in a scaled testing facility or on the open ocean, experimental testing reduces risk in a number of ways, including verifying offshore behavior and validating numerical performance models. Although it might sound obvious, accu-

Over the past half-century, more than 1,000 patents have been filed around the globe for various wave energy conversion systems and components. rate physical scaling of the prototype is essential to observing and assessing scaled physical performance and to identifying physical behaviors that might otherwise be simplified, or not identified by numerical models alone. Accurate, well-planned physical model experiments increase confidence in numerically modeled results and also serve to answer questions for which numerical models may be inappropriate.

Columbia Power has made extensive use of experimental testing. The first generations of WEC prototypes were linear direct-drive (LDD) devices. The initial tests on the LDD system were conducted

by Oregon State University in their long wave flume (LWF) at the Hinsdale Wave Research Laboratory (HWRL) in 2004. This early testing demonstrated the concept that an LDD permanent magnet (70) marine technology July 2013

generator (PMG) was a potentially feasible solution for converting wave power into electrical power. Following refinement of the LDD concept and licensing by Columbia Power, a 1 kW device (v1.0) was deployed off the coast of Newport, Oregon in 2007. In 2008, a 10 kW second-generation LDD device (v2.0), with improved hydrodynamic performance, was deployed at the same ocean location.

Projected cost of energy and reliability considerations at utility scale necessitated a departure from the LDD design and the creation of a new concept using direct-drive rotary (DDR) generators.

The resulting third-generation (v3.0) concept was tested at 1/50 scale in a pool fitted with a wave flume to confirm body motions and offshore behaviors. In 2009, a 1/33 scale fullyinstrumented v3.0 prototype was tested in the Tsunami Wave Basin (TWB) at HWRL, providing detailed experimental data on energy extraction efficiency.

In 2010, a 1/15 scale v3.0 system was tested in the LWF at HWRL. In addition to energy performance, assessing survival operation was an important aspect of these tests. During this set of experiments, significant wave heights of 14.85 m were evaluated, with single wave events reaching 29 m full scale equivalent.

Surprisingly, this 1,150 lb. (522 kg) displacement, 1/15 scale WEC experienced maximum mooring loads of only 28.0 N. Numerically-driven hydrodynamic design optimization led to the subsequent v3.1 design, which was tested at 1/33 scale in the TWB at HWRL, both as a single WEC and in three- and five WEC arrays. In February 2011, a 1/4.5 scale v3.1 prototype was deployed for thirteen months of sea trials in Puget Sound.

Following this deployment, the hydrodynamic design was further optimized (v3.2) and was recently tested at 1/33 scale in the HWRL TWB. Testing data was gathered to validate performance and mooring models in both operational and extreme seas. We are currently designing the StingRAY utility-scale DDRWEC using the v3.2 design, with planned open-ocean testing of a full-scale system in 2014-2015.

At smaller scales, it can be difficult to accurately represent all aspects of the full-scale WEC. For example, at 1/33 scale, certain design tradeoffs are necessary in the PTO. Even with room for an optimal generator, power electronics and instrumentation, the components do not scale, and the model will likely have a significant deviation in mass distribution compared to the target. When designing and building these models, care needs to be taken in order to reduce friction in the PTO, as torque Froude scales to the 4th power, such that at 1/33 scale, a mere 0.1 Nm torque would be equivalent to 120,000 Nm at full scale.

Mooring lines are also difficult to properly scale and the commonly available materials may have limited regions of accuracy and characteristics that are subject to change over time as well. To address these challenges, we collaborated with Oregon State University and the National Renewable www.sname.org/sname/mt

Aft float

PTO pods

Nacelle Forward float

Waterline

Spars

Mooring lines The StingRAY is a hydrodynamically optimized WEC with a tri-member fiberreinforced polymer hull.

Energy Laboratory in developing a programmable mooring controller, which uses feedback from a load cell and an encoder to control a motor. It also implements a scale-appropriate user input load extension profile.

Numerical modeling Numerical modeling is an essential tool in the development of WEC technology. While physical experiments are certainly necessary to the process, a validated hydrodynamic model yields answers much faster and with significantly less expense. We have made extensive use of ANSYS AQWA, a commerciallyavailable, multi-body-hydrodynamic-modeling software suite, www.sname.org/sname/mt

using the boundary element method (BEM). BEM solvers are based in linear wave theory, and rely upon the assumptions of small-amplitude waves and small-amplitude motions. The small-amplitude motion assumption is particularly problematic because, unlike many other ocean technologies, WEC devices are designed to have a large-amplitude response to the incident waves. In point of fact, care must be taken in interpreting the results of this or any frequency domain solver, as the model may predict unrealistically large responses near resonant frequencies.

While frequency domain solutions can be very fast, time domain solvers can introduce important non-linear effects.

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A 1/33 scale v3.0 prototype was tested in 2009 in the Tsunami Wave Basin at the Hinsdale Wave Research Laboratory.

For example, while AQWA’s time domain solver calculates the diffraction and radiation forces based on a structure’s mean position, the Froude-Krylov and hydrostatic forces are calculated based on the instantaneous wetted surface. This enables greater accuracy with larger motions or larger waves.

Furthermore, custom scripts can be linked to the time domain model to model fully non-linear PTOs and other external loads.

The primary objective of Columbia Power’s modeling program to date has been the assessment, and optimization, of WEC performance. Performance is often communicated as a power

During this set of experiments, significant wave heights of 14.85 m were evaluated, with single wave events reaching 29 m full scale equivalent. matrix—a discrete response surface that can be a function of two or more parameters. Device performance will vary with the characteristic wave height and period. Other factors to which a device may show significant sensitivity may include spectral shape, relative wave heading, and directional spreading. The N-dimensional power matrix may be convoluted with a wave occurrence table for

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a given site to estimate the mean annual energy production, which is an important WEC performance factor.

As progress is made towards commercialization, design considerations beyond performance become increasingly important. Structural design certification requires obtaining hydrodynamic loading as a pressure distributed across the hull in the time domain. This load distribution is not an option with our primary modeling tool and the accuracy of modeling in extreme seas with a BEM solver is questionable. Other modeling tools are being investigated, considering the tradeoff between increased accuracy and associated increased modeling run times. Some fluid-structure interaction models take days of computational time to run seconds of simulation time.

Technology design selection Integrated WEC designs must consider factors such as shape, PTO, mass, and inertia and mooring, as well as site-specific met-ocean conditions. Having identified the DDR PTO to be of primary importance, Columbia Power, in collaboration with GL Garrad Hassan, conducted extensive numerical modeling to investigate six major WEC body configurations able to incorporate the proposed PTO. Optimizations were then performed on shape, center of gravity, inertia, mooring, and damping to derive the v3.0 design in 2009.

In addition to the incorporation of the DDR PTO in the v3.0 design, the shift from the linear (v2.0) to rotary (v3.x) system has enabled a greater range of potential energy capture and more optimal performance, as well as lower relative capital and operating costs and the elimination of end stop risk.

www.sname.org/sname/mt

Validating the Wave Energy Model

The optimization leading to the v3.1 WEC marked our first major use of ANSYS AQWA as a design tool. More than 350 discrete shapes were numerically modeled in the frequency domain, resulting in a short list that was evaluated by Ershigs, Inc., our hull manufacturing partner, to optimize manufacturability and costs. The v3.1 design variant resulted in a large-diameter nacelle, which enabled the PMG diameter to be increased, providing for higher-efficiency operation at lower speeds. The final design also enabled a hull geometry that is easier to manufacture and resulted in an estimated 230% increase in energy production.

Following successful deployment of the 1:4.5 scale v3.1 WEC, a decision was made to redesign the WEC hull structure to avoid the expense and risk of range-of-motion-limiting end stops. Nearly a thousand simulations were run to investigate the effects of hull geometry and mass distribution using AQWA’s time-domain numerical-modeling module. The resulting design changes (v3.2) enabled both floats to rotate 360 degrees without collision, while predicting annual energy production nearly twice that of v3.1.

Testing of a 1/15 scale v3.0 system in the long wave flume at the Hinsdale Wave Research Laboratory in 2010.

Mooring design Moorings for offshore structures have evolved as improvements in oil and gas platform technology have enabled ever-deeper installations. The vast majority of these deep-water mooring systems are intended to provide stationkeeping for the surface floating topsides. In addition, these systems are designed for operation and maintenance by onboard personnel that require stable platforms to perform their jobs effectively. In contrast, WECs are fully autonomous, unmanned, and need good motion to harness kinetic energy and create electricity. The associated mooring designs, while similar in nature to their offshore oil and gas counterparts, have different design objectives.

The goal for the WEC mooring system design is based on maximizing energy conversion for the WEC, while providing stationkeeping for the loading and met-ocean conditions at the selected site. Survivability requires that the system have high static stiffness, which will avoid large excursions in surge and wave-to-wave dynamic response, in order to maximize energy capture potential. An additional challenge is the desire to reduce the horizontal excursion of the device as much as possible, to maximize placement density with compact arrays or wave farms.

Balancing the mooring design objectives with the capital expenditures, including fabrication, installation, and maintenance costs, is required for a successful system design.

www.sname.org/sname/mt

A 1/33 scale v3.2 WEC system was recently tested in the Tsunami Wave Basin.

Columbia Power uses a single-point mooring configuration that reduces costs and enables the WEC to orient itself into the wave field much like a weather vane, which helps to maximize energy capture. An added benefit to this single-point design is its low environmental footprint as compared to a more common three-point mooring configuration.

Modeling the WEC device and various mooring configurations with tools such as OrcaFlex has played a key role in the development and advancement of the understanding of the challenges for a marine-based energy conversion device. The ability to compare multiple device geometries and mooring configurations, for various weather conditions, enables rapid assessment of energy capture potential and evaluation of different mooring design tradeoffs.

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Validating the Wave Energy Model The technical evolution of the Columbia Power WEC systems.

The environmental conditions are different for every potential deployment site, including local changes in wind, wave, and current conditions, as well as seafloor geophysical and geotechnical conditions where anchors interface. The result is a cascading impact on design requirements, which creates challenges in defining common requirements for infrastructure while keeping overall costs competitive.

Energy conversion and PTO We performed extensive cooperative research with the Wallace Energy Systems & Renewables Facility at Oregon State University (OSU) on direct-drive systems to increase efficiency and reduce operation and maintenance (O&M) costs before selecting the DDR PTO. Reliability and survivability are among the most important design criteria for the design of an unmanned offshore system.

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A DDR PMG enables the elimination of mechanical systems and components and the electrical control of PTO load, reducing risk of failure and making the PTO system more robust. There also is increased material efficiency relative to the LDD generator alternative. Power from ocean waves is pulsed, with high force and low speed, and it is most efficient to smooth the power pulses early in the energy conversion process. Power smoothing can cause energy loss, and for most efficient conversion, it is desired to be able to convert a wide range of speeds and torques, minimizing cut-off regions. The use of a direct-drive generator, coupled with power electronics, enables an efficient and wide range of operation.

The lifecycle cost of a WEC includes both capital and O&M components. A WEC is designed to operate 24/7 for 20 years with roughly 10,000 wave cycles a day under heavy loads. The O&M costs can dominate when considering www.sname.org/sname/mt

operations at sea, and the reliability of DDR PMG generators has the potential to significantly reduce O&M costs, thereby lowering the cost of energy.

Next generation systems The first generation of WECs will be designed with high factors of safety and with operational functionality that demonstrates survivable and reliable operation at sea, but without being fully optimized. The succeeding generation of devices will be optimized for cost of energy and adapted for a broad range of operational locations for electric utility uses, and even for new applications that provide predictable power to many remote offshore needs.

All cases will benefit from the relentless focus on increasing power output and reduction of capital, operating, and maintenance costs, in order to continuously drive down the cost of energy. This is a well-understood learning process that occurs across a wide range of technologies, resulting in a relatively consistent level of improvement with each doubling of installed capacity. Capital and O&M cost improvements come primarily over time from reduced factors of safety and the advantages of manufacturing and deployment at scale. Performance models enable the potential rate of progress to accelerate and the most dramatic improvements to take place in the early stages of development.

Increased power output will derive from improved control strategies and hull shapes that seek to optimize the

The succeeding generation of devices will be optimized for cost of energy and adapted for a broad range of operational locations for electric utility uses. hydrodynamic capture performance across the full spectrum of geographic locations and sea states. The primary objective is utility-scale wave farms in the temperate zones, but the ability to use WECs to power anything from sensor buoys to remotelyoperated or autonomous underwater vehicles means that scale and form will surely be adapted across multiple applications.

Confidence in computer models enables rapid and costeffective evaluation of performance in any number of potential operating conditions, as well as for potential performance improvements from design variants. The scaled development process, with controlled physical experiments in wave tanks and well-measured experiments in sea trials, provides that desired high level of confidence in computer models. MT For more on the engineering team at Columbia Power Technologies, see the Feature Contributors on page 5.

The Manufacturing Side Composites represent a time-tested solution for the environmental extremes present in the ocean. They offer a number of cost-avoidance and reduction properties, such as a high strength-to-weight ratio and corrosion resistance, that make the choice appropriate for a long service life marine system such as the Columbia Power WEC. In general, a number of composite manufacturing processes are available for component fabrication: filament winding, hand layup, and vacuum infusion processes. The manufacturing process chosen for each structural component is specific to the type of properties—strength, manufacturability, and efficiency—required for performance during operation. As the WEC is considered a green technology, an effort is being made to construct the buoy with that same consideration. Traditional fiberglass components in the past have been made using spray-up equipment (a chopper gun). Although components can be fabricated quickly www.sname.org/sname/mt

with this method, it produces excessive waste and introduces pollutants, or volatile organic compounds (VOC), to the atmosphere.

The vacuum infusion process will be used in the fabrication of many WEC components because it helps to control, or even eliminate, VOCs from entering the environment. By using one of the three planned infusion processes—bagging, tite-RTM, or closed cavity bagging—component fabrication becomes a repeatable process, creating less waste, while virtually eliminating VOCs. Complex shapes can be constructed, eliminating the need for expensive machining, and components can be made to finished dimensional specification in most cases. Vacuum infusion also enables Columbia Power to take advantage of increased material strength while reducing structural thickness. This reduction in material usage and downstream finishing translates into lower fabrication costs and helps us achieve our cost of energy targets.

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(focus on education)

Hands-on laboratory demonstrations, such as this one concerning waves, often make the difference between student apathy and engagement.

Skill Sets Tailored to MRE Educational innovation will be needed to create a workforce for a new industry

By Howard P. Hanson, Susan H. Skemp, and Camille E. Coley

E

arth’s oceans have long been recognized as a potential source of energy. Indeed, for centuries some of this potential has been put to use by seafarers who have exploited favorable winds, tides, and currents to speed their passage. More recently, the international push to develop sustainable alternatives to the continued reliance on fossil fuels has rekindled interest in a variety of renewable energy sources, including those of the marine environment. Waves, tides, winds offshore, and ocean currents are all potential sources of renewable energy that are under active investigation as possible contributors to a diversified portfolio of energy sources for a sustainable future.

As these marine renewable energy (MRE) sources become commercialized, there will be new industries that arise. As a result, opportunities to advance the art, science, and practice of naval architecture, shipbuilding, and

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marine engineering in the context of MRE could hardly be brighter. Education represents one challenging opportunity in this regard, as the future MRE industry will need a variety of naval architects and marine engineers with skill sets tailored for the unique needs of MRE developers and operators. Meeting this challenge will require not only hybrid curricula in post-secondary education, with new innovations grounded on traditional approaches, but also a new educational pipeline to get younger students interested in MRE as a future career.

Much of the recent impetus for MRE research and development can be credited to the Wind and Water Power Program at the United States Department of Energy. In addition to its focus on advancing technology for MRE and accelerating its market penetration, the program has recognized the need for education and training for the future, and has underwritten such activities at the www.sname.org/sname/mt

Underwater operation, as always, adds complexities and challenges that dwarf those in the world of wind power.

Southeast National Marine Renewable Center (SNMREC) at Florida Atlantic University.

Something old, something new For naval architects and marine engineers, MRE offers a little of everything traditional plus several unique challenges, all wrapped in a new package. Consider, for example, the challenge of capturing the energy of ocean currents and tidal flows using underwater turbines. Rotation rates much slower than those of propellers mean that rotor designs will likely lean more toward those of wind turbines. However, the forces of the water—generally an order of magnitude larger than those in air would be for similar amounts of power—mean that structural designs must be significantly strengthened not only for rotor blades and hubs but also for bearings and gear assemblies.

Underwater operation, as always, adds complexities and challenges that dwarf those in the world of wind power.

Deep-water deployments, in particular, will require moored, buoyant systems that must operate autonomously below the draft of surface ships and remain stable in the face of currents that vary in three-dimensional space as well as in time. Yet the design of such systems—which will likely require hydrodynamic control surfaces to augment controllable buoyancy in order to achieve system stability—must include provisions for maintenance procedures in ways that are both safe and economical. In addition, the anchors and mooring hardware itself must accommodate both these dynamic considerations and, in some fashion, electrical transmission.

These examples for open-ocean currents are mirrored for tidal flows and wave energy. In all cases, the mechanical systems must be integrated seamlessly with the control and power-generation electronics, with autonomy in operation a guiding principle. While many of the challenges involved have analogies in more traditional naval architecture and marine engineering fields, the requirements for MRE equipment also include new and unique challenges that, in turn, require new educational preparation.

A first step At this stage of the industry, it is premature to invent new college-level majors or other specialized sequences. www.sname.org/sname/mt

Still, it is appropriate to begin thinking about the educational pipeline problem to prepare students who may wish to pursue such training in the future. To that end, SNMREC has developed a secondary-school curriculum that can be presented in pieces or as a package to midlevel high-school students. It was designed specifically to be compliant with state of Florida educational standards for science (the “Sunshine State Standards”), yet it was also designed to be self-contained in order to minimize the need for prerequisites. To that end, it covers a broad range of topics including background associated with renewable energy generally and topics beyond the technology of MRE. The six main lessons in the curriculum, each designed to be covered in 2-4 class sessions, reflect this philosophy and are structured as follows.

LESSON 1. Why do we need renewable energy? A survey of how society depends on electricity and the various concerns about dependence on fossil fuels.

LESSON 2. How is electricity generated? Some of the basic physics of electricity and magnetism, including Ohm’s Law and an exercise in which students construct simple electrical generators from soda cans.

LESSON 3. How do we identify energy from ocean currents with the best potential for producing energy?

Very basic oceanography with emphasis on the Gulf Stream.

LESSON 4. Harnessing energy from ocean currents: The new renewable. Overview of the technology involved with MRE recovery, including turbines and some fundamental physics such as the Bernoulli effect.

LESSON 5. What are the environmental impacts of ocean energy? Introduction to issues concerning effects of MRE recovery on sea life, with an emphasis on Florida species and a comparison of renewable and non-renewable energy sources and the environment.

LESSON 6. The future of ocean energy. Overview of the various modes of ocean energy (waves, tides, currents, and so forth) and their potential with an emphasis on the fundamental physics of ocean thermal energy conversion.

In addition to these lessons, the curriculum includes background material for teachers with an extensive bibliography, as well as a list of supplies needed and, July 2013 marine technology

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Skill Sets Tailored to MRE continued

SNMREC’s teacher workshops included hands-on instruction in all of the exercises in the curriculum. Here, building a soda-can electric generator is providing a challenge for the participants.

importantly, the specific Sunshine State Standards that the various lessons in curriculum address.

As part of the educational component of SNMREC, the center held a series of workshops in which science teachers, more than 200 to date, from seven counties in southeast Florida were trained as “master teachers,” so that they could train their colleagues in the use of the curriculum. The material is now becoming infused through the school districts and, we hope, generating interest in both MRE and more generally science and engineering in the student population. While it is too soon to have concrete results in terms of district penetration and student success, the feedback from the teachers in the workshops has been highly encouraging. Next steps include broadening the curriculum to be appropriate for younger students and strengthening it with additional modules such as one related to public policy about renewable energy.

Another less formal means of reaching students is through school and scouting field trips to SNMREC research laboratories located at the Harbor Branch Oceanographic Institute (HBOI) and the Dania Beach campus of Florida Atlantic University. During these field trips, science, technology, engineering, and math all come to life in explorations of the process being undertaken to harness the energy of the Florida current. Hands-on experiences provide a day of learning, inspiration, and fun as students see the turbine, its blades, and other equipment up close.

Finally, college students are engaged in the activities of SNMREC through a summer internship program

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in marine science and technology at HBOI. The 10-week program provides upper-level undergraduate and graduate students with an immersion in a research environment with the added dimension of having an MRE focus. A wide variety of topics are offered, including aquaculture; biomedical marine research; marine biology; marine mammal research; marine natural product chemistry; marine microbiology; ocean engineering; ocean technology; and oceanography.

Depending on the background and interest of the student, MRE-related issues can be the focus of several of these, and each intern is assigned to an appropriate researcher as a mentor in a project of mutual interest. At the culmination of the program, the intern is expected to submit a comprehensive written report on his or her project and give an oral presentation. Just as private-sector internships provide students with real-world experience in their field of study, these HBOI experiences prepare the interns for their future careers.

Beyond the schools Just as relevant as the formal education associated with curricula such as that described here is the informal education for the broader public about MRE and its potential as a resource for a sustainable future. This is particularly important given the fact that MRE implementation will use the oceans for a new purpose, one by which many people feel threatened. Environmental issues are especially important in this context.

In addition to the field trips mentioned earlier, another approach to such informal education is through public appearances at meetings of interested community groups. As successful as that can be—and the interaction of a question-and-answer period is useful for alleviating public concerns—it reaches but a small subset of the general public. Consequently, SNMREC also is reaching out more widely in partnerships with local museums to create interactive displays related to MRE and its future. At this point, the program is in the trial stages, but if it succeeds, it will offer a new way to inform and educate the public about the exciting opportunities of MRE. Given that public acceptance of this new idea is critical for its successful future, the MRE community broadly will benefit from these outreach efforts. MT At the Southeast National Marine Renewable Energy Center at Florida Atlantic University, Howard P. Hanson is scientific director, Susan H. Skemp is executive director, and Camille E. Coley is associate director. www.sname.org/sname/mt

(in review)

Efficiency, Reliability, and Modeling REVIEWED BY MICHAEL KLEIN-UREÑA

I

f you have ever felt vexed by the growing number of environmental requirements that apply to the marine sector, you are not alone. The International Maritime Organization (IMO) has released several guidelines (soon to be regulations) on energy-efficient ship design and operation. This new book by Indra Nath Bose is an excellent resource for understanding the application and impact of IMO guidelines on energy efficiency that target greenhouse gas emissions. The book does not cover SOx or NOx emissions regulations as they are not part of Energy Efficiency and Ships EEDI or SEEMP standards.

By Indra Nath Bose Bose introduces the book with a Published by brief history and context of the IMO THE INSTITUTE OF MARINE efforts to reduce greenhouse gas ENGINEERS (INDIA) emissions in the shipping industry, and with summaries of the different guidelines that were developed to address these emissions.

The book is then divided into two principal sections: Energy Efficiency Design Index (EEDI) and Ship Energy Efficiency Management Plan (SEEMP). The bulk of the text is devoted to EEDI, which comes as no surprise; calculating the EEDI value for a vessel is a multi-step process that is largely dependent on vessel type and size. Bose carefully explains the process of calculating a vessel’s EEDI value, verifying that value in full-scale trials, and comparing the attained EEDI value to the required EEDI value for the particular vessel. The text is well supplemented with derived equations, lists of assumptions, and tables of correction factors. www.sname.org/sname/mt

The section on SEEMP provides a broad list of operational measures that could be included in a vessel’s own SEEMP. Bose reviews all the options, from weather routing to crew training. The chapter reads like a state-of-industry text on SEEMP compliance; not every option is suitable for every vessel, but the utility lies in having as much information as possible in one book.

Finally, Bose briefly touches on Energy Efficiency Operational Indicator, which describes a vessel’s total energy efficiency based on its design and operation profile.

A few other features make the book particularly useful as a reference tool. Each paragraph is uniquely numbered to enable simplified future reference. Bose also includes a guide to the new chapter 4 of MARPOL Annex IV, which contains most of the IMO energy efficiency rules. Finally, there is a comprehensive annexure of relevant IMO guidelines for which Bose provides detailed explanations.

The biggest shortcoming of the current edition is the number of stylistic inconsistencies within the text (for example, hyphenation and capitalization). These inconsistencies do not significantly detract from the validity of the content, and should be corrected in future editions.

Bose’s text provides a breadth of information pertaining to the EEDI and SEEMP standards set by the IMO. Energy Efficiency and Ships is highly recommended to any ship designer or ship operator as a useful reference tool, and to any shipowner who would like to become conversant in energy efficiency. It also is suitable for undergraduate students as a supplementary text to energy-efficient ship design and operation. The book provides easy-to-follow information that enables the reader to develop, and to appreciate the complexity of quantifying a vessel’s energy. Standards for energy efficiency vary greatly from vessel to vessel; hence, the need for a publication such as this one. MT Michael Klein-Ureña is a member of SNAME and a founding member of Technical and Research Panel EC-10, Marine Vessel Environmental Performance.

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(in review)

REVIEWED BY CARL DELO

T

his book is part of the publisher’s physics catalog, and is intended for a general audience. However, the central topic of the book, modeling vessels, is treated in the context of the history of technology. Part III, which covers the advent of systematic scale model testing in modern hydro and aerodynamics, focuses primarily on the formative work of William Froude, David Taylor, and the Wright brothers. The evoluModeling Ships and tion of scale model testing in place of full-sized Space Craft: the Science prototypes is described in some detail. and Art of Mastering the The financial pressures that first spurred scale Oceans and Skies model testing of ships, and the struggles of Froude

By Gina Hagler and Taylor to institute rigorous and comprehensive Published by SPRINGER hydraulic testing programs to support and advance SCIENCE AND BUSINESS the burgeoning maritime industry, is engaging.

MEDIA, LLC By comparison, the small-scale investigations of the Wright brothers in the new field of aeronautics become all the more impressive in comparison. It is truly remarkable that two men working systematically and doggedly could exert as much influence on the modern world as the large government research efforts that Froude and Taylor eventually commanded.

These chapters on the early modelers contain interesting historical photographs, laboratory schematics, and machine

REVIEWED BY DAVID A. BRESLIN

S

ome of us can remember back to a time when reliability was always of utmost importance when making decisions on which product to buy. Smart buyers wanted to avoid buying products that could be impolitely, if not accurately, referred to as “junk.”

Thankfully times have changed in many industries such as consumer electronics, and often, reliability now can be taken for granted. But Practical Reliability that’s not necessarily the case in all industries, Engineering, Fifth Edition which is why books such as Practical Reliability

By Patrick D. T. O’Connor Engineering are so extraordinarily valuable. and Andre Kleyner What is reliability? Simply stated, it is the Published by probability that an item will perform a required JOHN WILEY & SONS, LTD. function without failure under stated conditions for a stated period of time. Reliability is important.

After all, a product with poor reliability can have undesirable consequences. Owners and operators of unreliable products are left to contend with unanticipated maintenance and repair costs, harmful interruptions to operations, premature (80) marine technology July 2013

drawings. There is not much discussion of the figures, however, so they are useful primarily to those who are experienced at interpreting such drawings. The end of part III contains a section on rocketry (not space craft, as the title suggests), also from a historical viewpoint. As in the prior chapters, the underlying physics of the model testing is a secondary issue. In some cases, important concepts are glossed over or incomplete. This treatment is not a serious drawback in the framework of the narrative, as a reader interested in the engineering details of model testing will likely move on to more advanced texts.

The book becomes problematic once it strays from its central topic. Part I of the book deals with airborne and aquatic animals.

Unfortunately, there are numerous examples of misinterpretations of basic physical principles, omissions of important concepts, and outright errors of fact in the explanations of how animals fly or swim. Part II covers the evolution of hydrodynamic and aerodynamic theory, but contains misstatements of the Bernoulli Equation, Newton’s Laws of Motion, the causes of lift and drag, the source of the Magnus effect, and more.

The glossary of technical terms also is rife with errors.

Readers are advised to look elsewhere for insight into these topics and to consider this a work of history rather than physics. MT Carl Delo, PhD, is a SNAME member and associate professor of mechanical engineering at SUNY Maritime College, where he is currently developing a new hydrodynamics laboratory.

replacement costs, and perhaps the possibility of injury or death of innocent workers and bystanders. And for designers and manufacturers, the consequences include higher warranty costs, legal liability, damage to brand image, and the departure of once-loyal customers.

So the concept of reliability is simple, and the benefits of high reliability are apparent. But engineering products that will be reliable in service can be complicated. This is especially true for products that economists classify as durable goods—products that have useful lives of three years or more. After all, how does one determine the probability that a new product will perform as required given the variability inherent in material properties, manufacturing processes, product use, and user knowledge? And if it is determined that the probability will not meet user requirements, then what is the best strategy for reengineering the product to improve its reliability without unduly affecting cost, size, weight, and schedule?

Fortunately, the answers can be found within the pages of this book. The authors begin by carefully laying out the principles of reliability engineering, starting off with a review of the applicable theories of probability and statistics, which are fundamental to the effective application of reliability engineering. The authors then www.sname.org/sname/mt

move into the topics of life data analysis; loadstrength interference; prediction and modeling; design; testing; demonstration and growth; manufacturing; and maintenance. The material is relevant to any product design, whether mechanical or electrical, from simple, disposable components to highly complex systems with long service lives. And each well-written chapter builds upon each previous chapter, covering the material thoroughly and presenting examples that are both insightful and germane.

Consider all of this from the standpoint of a customer. On the one hand, a customer typically values increased levels of product reliability. On the other hand, budgets are tight and pockets are only so deep.

But with the right engineering knowledge, one quickly learns that increasing levels of product reliability do not necessarily mean

www.sname.org/sname/mt

higher costs; just think of consumer electronics. Having the ability to define loads and strengths both probabilistically and accurately enables products to be designed without unnecessarily conser vative margins. And correcting for the misapplication or over-application of redundancy can result in systems that comprise fewer components, have greater reliability, and actually cost less. With the correct knowledge and insight available from Practical Reliability Engineering, it becomes obvious that less can, in fact, be more for everyone.

For those who are familiar with earlier editions of the book, this fifth edition corrects many annoying typographical errors. In addition, it introduces a brand new chapter on the application of Monte Carlo simulations to the field of reliability

engineering using common software, showing readers the basics of creating models to analyze systems of any level of complexity. This new chapter will not intimidate anyone, and is useful for both experts and those who are complete novices in the field.

Although designed for an academic setting, this book is suitable for any engineer interested in self learning. In fact, any engineer who invests the time to read this book will delight both his or her supervisors and customers by being better equipped to design systems and components that are more reliable. MT David A. Breslin is a PE and a member of SNAME, teaches reliability engineering and operations research for the United States Merchant Marine Academy, and is a marine engineer for the United States Navy.

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(abstracts)

SNAME Paper Abstracts Editor’s note: The following are abstracts of papers recently presented at SNAME events and/or published in SNAME publications. The papers can be found at www. sname.org/sname/mt/featuredabstracts

View current and previous issues of Journal of Ship Production and Design and Journal of Ship Research at http://www.sname.org/SNAME/Pubs/Journals1/

Physics-Based Learning Models for Ship Hydrodynamics

BY GABRIEL D. WEYMOUTH AND DICK K.P. YUE PUBLISHED IN THE MARCH 2013 JOURNAL OF SHIP RESEARCH

We present the concepts of physics-based learning models (PBLM) and their relevance and application to the field of ship hydrodynamics. The utility of physics-based learning is motivated by contrasting generic learning models for regression predictions, which do not presume any knowledge of the system other than the training data provided with methods such as semi-empirical models, which incorporate physical insights along with data-fitting.

PBLM provides a framework wherein intermediate models, which capture some physical aspects of the problem, are incorporated into modern generic learning tools to substantially improve the predictions of the latter, minimizing the reliance on costly experimental measurements or high-resolution high-fidelity numerical solutions. To illustrate the versatility and efficacy of PBLM, we present three waveship interaction problems: at speed waterline profiles; ship motions in head seas; and threedimensional breaking bow waves. PBLM is shown to be robust and produce error rates at or below the uncertainty in the generated data at a small fraction of the expense of high-resolution numerical predictions.

Uncertainty Analysis of Load Combination Factors for Global Longitudinal Bending Moments of Double-hull Tankers

BY ANGELO P. TEIXEIRA, C. GUEDES SOARES, NIAN-ZHONG CHEN, AND GE WANG PUBLISHED IN THE MARCH 2013 JOURNAL OF SHIP RESEARCH

This article aims at assessing the probabilistic (82) marine technology July 2013

characteristics of the load combination factors for global longitudinal bending moments of double-hull tankers. The calculations are performed based on a sample of oil tankers representative of the range of application of the Association of Classification Societies’ (IACS)-Common Structural Rules (CSR) design rules. The article starts by reviewing the probabilistic models that have been proposed to model still water and wave-induced loads and their characteristic extreme values. Different load combination methods are also reviewed, including an analytical method that provides the combined characteristic value of still water and wave-induced bending moments based on the Poisson assumption for upcrossing events and using the first-order reliability method in combination with the point-crossing method. The predictions of the different load combination methods are assessed on the basis of a sample of five oil tankers adopted during the IACS-CSR design rules development process.

A parametric and an uncertainty propagation study are then performed to identify the range of variation and the probabilistic models of the load combination factors that are applicable to double-hull tankers.

hydrodynamic lift. This article explores the relationship between the hydrostatic lift and righting moment, the hydrodynamic lift and righting moment, and the total lift and heelrestoring moment of a planing craft operating at planing speeds. A series of tow tests using a prismatic hull with a constant deadrise of 20° measured the lift force and righting moment at various angles of heel and at various model velocities. The model was completely constrained in surge, sway, heave, roll, pitch, and yaw. The underwater volume is determined from the known hull configuration and the underwater photography of the keel and chine wetted lengths. The results presented include the total lift and righting moment with the hydrostatic and hydrodynamic contributions for various model speeds at two model displacements.

Comparisons Between Prediction and Experiment for Lift Force and Heel Moment for a Planing Hull

This article presents a simplified approach to quantifying the comparison of acceleration responses of high-speed craft in rough seas. Statistical acceleration values, used to characterize craft seakeeping responses, including average of the highest one-third, one-tenth, and 1/100th peak accelerations and the root mean square acceleration, are used to define the relative ride severity index (RSI). The article first summarizes an unambiguous computational procedure for multiple investigators to calculate similar acceleration values. It then explains the theory and rationale for relating statistical acceleration ratios to an indication of potential damage, whether resulting from cumulative wave impacts or single severe slam events, that can be used in comparative assessments of structural integrity, equipment susceptibility to malfunction, or personnel comfort and safety. Example ride

BY CAROLYN Q. JUDGE PUBLISHED IN THE FEBRUARY 2013 JOURNAL OF SHIP PRODUCTION AND DESIGN

Even in calm water, high-speed vessels can display unstable behaviors such as chine walking, sudden large heel, and porpoising.

Large heel results from the loss of transverse stability at high forward speed. When a planing craft begins to plane, the hydrodynamic lift forces raise the hull out of the water. The available righting moment resulting from the hydrostatic buoyancy is, therefore, reduced. As the righting moment resulting from hydrostatic buoyancy is reduced, the righting moment resulting from dynamic effects becomes important. These hydrodynamic righting effects are related to the

Ride Severity Index: A Simplified Approach for Comparing Peak Acceleration Responses of HighSpeed Craft

BY MICHAEL R. RILEY, TIM COATS, KELLY HAUPT, AND DONALD JACOBSON PUBLISHED IN THE FEBRUARY 2013 JOURNAL OF SHIP PRODUCTION AND DESIGN

www.sname.org/sname/mt

severity comparison plots and computed values of RSI are presented to illustrate the simplicity of the approach and to demonstrate the ability to quantify what heretofore has relied primarily on the subjective experience of operators.

Uncertainties in the Wind-Heel Analysis of Traditional Sailing Vessels: The Challenges it Presents for Forensic Analysis of Sailing Incidents

BY B. JOHNSON, W. LASHER, M. ERDMAN, JAN MILES, AND B. CURR PUBLISHED IN THE 2013 CHESAPEAKE SAILING YACHT SYMPOSIUM PROCEEDINGS

There are many uncertainties in the interpretation of full-scale sailing vessel data taken under dynamic conditions, and even more uncertainties when forensic analysis is attempted based only on survivor’s recollections. Frequently, the analysis is based on static equilibrium assumptions, sometimes modified to steady-state motions of the wind and heeling response of the vessel.

Dynamic conditions are generally nondeterministic and statistical methods must be used. Even more complicated is the nonstationary random process nature of most accidents. In the wind-heel research carried out on Pride II, it has been shown that wave action frequently adds uncertainty to the correct attribution of contributions to establishing the cause of resulting heeling action. The best data are found in steady 10 to 20 knot wind strengths in minimum waves found in the lee of a shoreline. This criteria can be interpreted as minimizing the uncertainties in characterizing the wind-heel performance of a given sail combination at normal angles of heel. Examples of quasi steady-state response are presented in the paper as characterized by the wind heel stiffness ratio (WHSR), which is equal to the square of the apparent wind velocity in knots divided by the resulting heel angle in degrees. WHSR is not non-dimensional but is independent of the system of units, (SI vs. EG). The WHSR for each sail www.sname.org/sname/mt

combination is most easily established by a maneuver the crew of Pride II has deemed “the crazy Ivan.” However, it is uncertain whether this concept can make useful predictions at heel angles higher than those beyond GZmax in the absence of any good data taken during these conditions. CFD studies of various sail combinations provide very good agreement between the recorded wind-heels responses of the vessel up to deck edge submergence. The corresponding CFD predictions provide a method of predicting the normal wind heel responses of a traditional sailing vessel during the design process. The paper discusses operational guidance uncertainties that appear as a “fork in the road” decision, with bearing away as one path and heading up as the other. The paper examines the tradeoffs in the decision making process relative to the type of vessel involved

and the observable wind and sea conditions at the time. Recent attempts to re-analyze the dismasting of Pride II in 2005 and the sinking of Concordia off Brazil in 2010 also are included.

Development of Volvo Ocean 65

BY BRITTON WARD AND CHRIS COCHRA PUBLISHED IN THE 2013 CHESAPEAKE SAILING YACHT SYMPOSIUM PROCEEDINGS

For the 2014-15 Volvo Ocean Race, the organizing authority made a dramatic shift in direction for the next two editions of the race, opting to move to a smaller, less expensive yacht built to exceptionally strict one-design standards. This paper outlines some of the motivations for this shift and details some of the critical features of the new Volvo Ocean 65 design and how they compare to solutions on the previous

What are USCG/IMO Horn Requirements?

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Kahlenberg Industries, Inc. Two Rivers, WI USA

Ph: 920-793-4507 www.kahlenberg.com July 2013 marine technology

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Volvo Open 70 yachts. Discussion of the logistical complexities involved in building the fleet of boats in the required time also is discussed. A review of the structural design is included to illustrate the efforts to improve construction efficiency, reduce cost, and dramatically improve robustness of the yacht structures while minimizing the weight additions that result. Finally, we review some of the extensive quality control procedures and manufacturing technology that has been employed in an effort to achieve a fleet of one-design yachts that are as identical to one another as possible.

to support design, including a parametric study of hull form as it relates to stability at high angles of heel; the development of bespoke parametric design and analysis tools using the graphical algorithm editor Grasshopper; a towing tank campaign at the Wolfson Unit to investigate the behavior of three keel profiles; and a wind tunnel campaign at Politecnico di Milano to investigate the behavior of 15 sail plans. Preliminary results from these studies will be presented, set in the context of the unfolding story of the evolution of the design of the new vessel.

A Wind Tunnel Study of the Interaction Between Two Sailing Yachts

Uniform-Panel Weld Shrinkage Data Model for Neat Construction Ship Design Engineering

BY P.J. RICHARDS, D.J. LE PELLEY, D. JOWETT, J. LITTLE, AND O. DETLEFSEN

By Yu-Ping Yang, Harvey Castner, Randy Dull, James R. Dydo, and Dennis Fanguy

PUBLISHED IN THE 2013 CHESAPEAKE SAILING YACHT SYMPOSIUM PROCEEDINGS

PUBLISHED IN THE FEBRUARY 2013 JOURNAL OF SHIP PRODUCTION AND DESIGN

The interference between two yachts sailing in several conditions is investigated in the wind tunnel by using two similar yacht models, one of which is mounted on a force balance and the other moved around the test section. The yachts were configured to sail close-hauled upwind at 20° apparent wind angle, downwind under asymmetric spinnaker at 60°, and downwind under symmetric spinnaker at 120° apparent wind angle. The regions of positive and negative interference are determined through aerodynamic force measurement and flow disturbance measurement, and the sources of these effects investigated.

A weld shrinkage prediction model was developed for thin uniform ship panels to predict in-plane shrinkage. The weld shrinkage prediction model consists of a series of empirical equations developed by analysis of shrinkage data from welded panels fabricated in the shipyards. These panels ranged in thickness from 3 mm to 9.5 mm and were welded with processes including submerged arc, flux cored arc, and gas metal arc welding. All fabrication data were carefully recorded using practices that were common over each of the shipyards. Measurements of the panels were made throughout each step of fabrication to provide accurate weld shrinkage data.

The data were then analyzed by regression analysis to produce equations that permit the calculation of weld shrinkage based on the conditions used for fabrication. These

The Evolution of Design: SALTS’ New Sail Training Schooner Project

BY S. DUFF, F. FOSSATI, ANDY CLAUGHTON, W. KRZYMOWSKI, AND TONY ANDERSON PUBLISHED IN THE 2013 CHESAPEAKE SAILING YACHT SYMPOSIUM PROCEEDINGS

The Sail and Life Training Society is building a new purpose-designed 35 m wooden sail-training schooner for unrestricted foreign-going operations. Working with an international team of consultants, SALTS has initiated an ambitious agenda of analytical and experimental investigations (84) marine technology July 2013

shrinkage model equations were embedded in a Microsoft Excel spreadsheet for ease of use.

Estimation of Resistance and SelfPropulsion Characteristics for Low L/B Twin-Skeg Container Ship by a High-Fidelity RANS Solver

BY NOBUAKI SAKAMOTO, YASUTAKA KAWANAMI, SHOTARO UTO AND NORIYUKI SASAKI PUBLISHED IN THE MARCH 2013 JOURNAL OF SHIP RESEARCH

Reynolds-averaged Navier-Stokes simulations, together with verification and validation studies for a low L/B twin-skeg container ship, are carried out using SURF version 6.44. This is a high-fidelity RANS solver for ship hydrodynamics developed at the National Maritime Research Institute: single-phase level set free surface, Spalart-Allmaras/k-ω turbulence, and body-force propeller models; finite volume discretization; and parallelized by openMP for high-performance computing.

At the beginning, simulation numerical uncertainty has been quantified for resistance and self-propulsion coefficients on the basis of the standard V&V procedure recommended by the International Towing Tank Conference. Then the resistance and self-propulsion simulations are carried out at several speeds ranging from low to medium Froude numbers.

The overall results are encouraging in that the solver accurately predicts resistance and self-propulsion coefficients as well as velocity distribution at the propeller plane in comparison to the available experimental data. Further sophistications in computational method, especially in estimating self-propulsion coefficients, will lead the solver to be a more practical and powerful design tool. MT

GO DEEPER Both the Journal of Ship Production and Design and the Journal of Ship Research are available by subscription. Go to www.sname.org/SNAME/Pubs/Journals1/ and find out why these technical journals are indispensable to naval architects and marine engineers around the world.

www.sname.org/sname/mt

(glossary) Acronyms, names, and terms appearing in this issue ADCF: advanced design cross-flow turbines, used in ORPC’s power systems

LCOE: levelized cost of energy, denoting the cost of energy generated by disparate sources

project commissioned and funded by the Energy Technologies Institute

AW-Energy Oy: Finnish company that is developing WaveRoller, a device that uses ocean surge wave energy

Magnetostriction: phenomena in which high-magnitude, low-displacement mechanical load changes are converted into magnetic flux changes and then electricity for large-scale energy production

RITE: Verdant Power’s Roosevelt Island Tidal Energy project site in New York City’s East River

CAB: Conformity Assessment Board, an independent body within the IEC, responsible for ensuring that standards developed by IEC technical committees are applied fairly and consistently Cobscook Bay Tidal Energy Project: ORPC’s hydrokinetic tidal energy project off the coast of Maine EMEC: European Marine Energy Centre, located in the Orkney Islands in Scotland, which has seven tidal test berths for testing of tidal energy devices ETI: Energy Technologies Institute EXWC: NAVFAC’s Engineering and Expeditionary Warfare Center, located in Port Hueneme, California FERC: Federal Energy Regulatory Commission HNMREC: Hawaii National Marine Renewable Energy Center IEC: International Electrotechnical Commission

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Yoshio Masuda: former Japanese naval commander who became a pioneer in the development of wave power technology

Stephen Salter: inventor of the “nodding duck” wave energy device SeaGen: a 1 MW free-stream tidal turbine located off the coast of Northern Ireland

NAVFAC: Naval Facilities Engineering Command

SNMREC: the Southeast National Marine Renewable Center at Florida Atlantic University

NELHA: Natural Energy Laboratory of Hawaii Authority at Keahole Point on the Kona coast of Hawaii

StingRAY: Columbia Power’s hydrodynamicallyoptimized WEC, which has a tri-member fiberreinforced polymer hull

NEPA: National Environmental Policy Act, signed into law in 1970

SWTS: shallow water test site

NREL: National Renewable Energy Laboratory OTEC: ocean thermal energy conversion, a process that takes advantage of temperature differences between ocean layers to generate electricity PerAWaT: Performance Assessment of Wave and Tidal Array Systems, a WEC tank-testing

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TC-114: a technical committee of the International Electrotechnical Commission that develops and maintains technical specifications and standards for the MHK sector TidGen: ORPC’s power system for tidal and deep river sites, with a rated capacity of 150 kW WEC: wave energy converter

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The Journal of Ship Research may have a new look but it continues to publish highly technical papers on applied research in hydrodynamics, propulsion, ship motions, structures, and vibrations. While SNAME requires that papers present the results of research that advances ship and ocean science and engineering, most contributions bear directly on other disciplines such as civil and mechanical engineering, applied mathematics, and numerical analysis. JSR has been ranked by IngentaConnect as being in the top 100 out of more than 13,530 titles hosted on their platform.

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(historical note)

Wave Energy Roots The technology goes back farther than you may think

By Campbell Wilson

T

he history of attempts to capture the power of water goes back to ancient times. Indeed, the conversion of the energy of water to mechanical power is perhaps the first example of the earth’s resources being harnessed for the benefit of mankind, predating even the windmill. Water can provide a host of energies, as power can be drawn from the flow of water, from waves, and from tides.

Also, in contrast to wind energy, water energy can be stored. For these reasons, water power is widely recognized as having played a central role in energy history, and historians such as Carus-Wilson and Nef have cited the importance of water power to earlier industrial revolutions. For our purposes here, the focus will be on one aspect of this hugely important energy source, that of wave energy.

The earliest recorded example of innovation in wave technology dates from 1799, when the Girards, a father and son team, patented their design for a wave machine

in Paris. Their idea was to attach a floating platform to the shore by means of a long arm, which would rise up and down with the action of the waves, thus creating mechanical energy. While it is not clear if this idea was ever tested, it is certain that the concept encouraged further attempts to capture the energy of the waves throughout the 19th and 20th centuries.

During the 19th century, and thereafter, the United Kingdom led the way in wave energy technology. This was due in part to its position as the first industrialized nation, but also to its enviable natural wave resource. It has been estimated that the U.K.’s potential wave energy resource ranges from less than 30 GW at the shoreline to approximately 80 GW in deep water. It is estimated that, between 1855 and 1973, more than 340 patents were granted in the U.K. for wave power devices. In the 19th century, patents for wave power were granted at the incredible rate of around three per year. This average doubled to six per year between 1900 and 1930, showing a particular surge after the First

Stephen Salter, inventor of the “Salter Duck,” at work with postgraduate students in his laboratory at Edinburgh University in 1977. A prototype model of the duck is visible in the background. Photo courtesy Heini Schneebeli / Science Source.

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Wave Energy Roots continued World War, before declining to an average of one patent per year from the 1930s.

Experimental stages However, despite this sustained burst of technological innovation, wave power appears to have remained largely experimental before the latter part of the 20th century. In fact, of the 340 patents, only 27 wave-powered devices were built before the mid-1970s. One of the earliest and best known of these was built at Royan, near Bordeaux in France in 1910. In this installation, a Monsieur Bochaux-Praceique supplied his house with 1 kW of electricity by means of an air turbine, which was driven by wave power. This air turbine design was later taken up very successfully by Yoshio Masuda in Japan.

Following a number of experimental installations that met with limited degrees of success in the 1920s and 1930s, the period following the Second World War saw wave power experiments begin to be more effective. Arguably, it was Masuda, a Japanese naval commander, who began the modern age of wave power technology. Beginning in 1947 with the Oceanographic Unit of the Japan Maritime Self-Defence Unit, Masuda ran a number of wave energy projects based on a three-float system. From the 1960s, the research and development division of the Japan Defence Agency supported much of this work in a clear attempt to locate reliable and plentiful energy supplies in a country almost devoid of fossil fuel resources. The Ryokuseisha Corporation also funded much of the development cost.

Masuda now concentrated his efforts on the air turbine design. After more than 10 years of work, he successfully demonstrated a 500 W wave-powered air turbine generator at Expo 1970, in Osaka. Masuda became a major exporter of air turbine buoys after 1965, and by the 1980s, there were more than 600 devices in operation in various parts of the world. Arguably, he remains the most successful commercial wave energy developer to date.

The nodding duck The turning point for wave energy, as for so many other renewable energy sources, came after the first global oil crisis in 1973. Prompted by the invention of the “nodding duck” wave device by Stephen Salter of the University of (88) marine technology July 2013

Their idea was to attach a floating platform to the shore by means of a long arm, which would rise up and down with the action of the waves, thus creating mechanical energy.

Edinburgh, the U.K. government funded a wave energy program until 1982. This provided financial support to many developers and various devices through the 1970s.

Although the program was eventually shut down due to competition from wind energy in the U.K., it did spawn many of the wave energy devices that we see around the world today, such as the Pelamis device.

During the 1980s and 1990s, wave energy suffered a lull. The rapid adoption of wind energy and the emergence of the ubiquitous wind farm pushed wave energy technologies into the background. Slowly, in the 21st century, governments and commercial developers have once again begun to consider the huge potential of wave energy. In the United States, a small amount of wave energy research and development was carried out in the late 1990s, but as in other countries, government support was either modest or non-existent. Some of the technologies developed during this period moved closer to commercial development in the early 2000s, but the global recession of 2007/2008 again served to stunt the growth of wave energy technologies in the U.S. and elsewhere.

More recently, an array of wave energy devices have emerged in various parts of the world and are beginning to make small but significant contributions to national energy supplies in some places, most notably in Scotland. The predictability and reliability of wave energy is now beginning to challenge the dominance of wind among renewable sources of energy. As wave technology developer Stephen Salter put it, “God pays for the waves. We only pay for the capital equipment to use them.” MT Campbell Wilson is acting director of the Top-Up program at the University of Glasgow in Glasgow, Scotland. www.sname.org/sname/mt

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