Hydropower

Marine Test & Research Facilities Open up the Deep

Issue 1 and Volume 13.

As any engineer will tell you, developing the engineering concepts for a novel energy production device is an iterative process. For ocean energy, this process is further complicated as any device destined to generate electricity from the marine environment must be sufficiently robust to survive the extremely harsh conditions, all the while maintaining complex operations at sea.

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Testing, measurement and understanding hydrodynamic interaction between the device and its environment can deliver on a number of key goals, chiefly: cost reduction through the better use of materials, improved control schemes, and lower cost next generation devices.

The design must also include consideration of, for example, the nature of the installation techniques required for the proposed machine and other issues such as scouring, electrical systems and operations and maintenance. Indeed, the challenges of wave energy are very similar to those of the wider offshore industry, requiring safe and economic design, production, transportation, installation, maintenance, repair and removal.

In achieving this, engineers must develop any such device on a foundation of sound design as marine renewable energy extraction requires considerable engineering, both of the devices themselves and also the mooring systems, umbilical connections, installation and maintenance infrastructure. This process is chiefly based around the three distinct phases of theoretical and numerical modeling, physical scale modeling and prototype installation.

Testing such engineering concepts to determine actual behavior can be achieved through numerical modeling. However the ability of numerical modeling to realistically represent the real environment is limited, particularly where complex problems are concerned, such as modeling water and air boundary layers. Often selected physical experimentation is undertaken as a iprocess of correlation in order to seek to validate that the numerical results are correct.

Once sufficient confidence in the fundamentals of a concept’s design has been established, developers can move on to more detailed designs considering individual components, such as mechanical and electrical linkages, seals and valves.

Inevitably, at each phase there may be a requirement for design revisions and subsequent re-modeling and testing. Thus, a typical design and development process could see repeated testing of components at a variety of scales before components and sections are integrated into a functional unit, which is built and tested again. At each of these stages the physical behavior is compared with a numerical model to ensure that the device is operating as expected and that the engineering principles are fully understood. Crucially, these phases of development should take place before significant large-scale prototype construction and its associated expense is conducted. Indeed, as a development tool, testing is vital not just in terms of mechanical and electrical design, but also in limiting development costs and mitigating financial risks. Following an extensive period of model basin testing at for example 1:20 or 1:50 scale, including power take off characteristics, the integrated system test phase is followed by full-scale prototype testing.

An Early Role for Universities

Much of the initial research on offshore energy devices is typically conducted at university wave basins and testing tanks. For example, Dr David Kaye, engineering manager at wave energy specialist Aquamarine explains how, partly as a result of the close relationship with Queen’s University Belfast, the company has conducted considerable development research at the university’s wave tanks.

Developer of the Oyster concept, Professor Trevor Whittaker, is both an Aquamarine shareholder and from Queen’s School of Planning, Architecture and Civil Engineering. Furthermore, the company is actively sponsoring PhD students and has staff on secondment to the university as part of a team of people at the wave testing centre site. The second generation Oyster II machine is currently undergoing device engineering and concept analysis at the university.

Indeed, Oyster was first conceived out of work funded by an Engineering and Physical Sciences Research Council grant to Queen’s University Belfast in 2002–2004, to develop surging power-wave devices at its large wave tanks facility.

Whittaker said, ‘The concept of Oyster came about through research in our wave-tank facility at Queen’s’, adding, ‘In fact Oyster is the third prototype demonstration wave power project which the team at Queen’s has instigated in the past 20 years.’

That strong links with academia should emerge from the early phases of development of novel energy devices with their unique engineering challenges is no surprise. Indeed, such relationships are not uncommon. For instance in the UK Pelamis Wave Power has close ties with Edinburgh University and Orecon with the University of Exeter and University of Plymouth.

Furthermore, it should also be noted that while such ties to academia may be considered an advantage of considerable value, not all successful marine energy device developers have them.

Bas Buchner, vice president of the Maritime Research Institute Netherlands (MARIN) and leader of its Renewable Energy Team, also explains that although this type of modeling provides valuable data, there is a very real danger that while initial engineering concepts are sound and early tank testing produces encouraging results, such concepts may have not been designed to withstand the harsh conditions found at sea. Buchner considers it vital that input and advice from the traditional maritime industry is sought before the move to full-scale prototypes. He says there have been examples of developments which have moved from the low-cost university basin modeling approach to full-scale sea trails using prototypes without this essential intermediate step. In some cases such a move has resulted in the entire loss of the prototype, and its associated expense, he says.

Noting an estimated bill of £10 million ($16 million) to install a 1 MW marine prototype, Andrew Mill of UK energy research centre Narec echo’s Buchner’s concerns that some developers do not have a strong background in marine devices, suggesting that commercial players bring valuable expertise in installation, operation and large-scale development, with access to specialist vessels for example. Mill also points to the growing interest of larger engineering companies entering the market, such as Rolls-Royce, Foster Wheeler and Siemens.

Another key advantage of using commercial installations for testing at larger scales is the ability to use larger and more complex waves as well as a tendency for better instrumentation at commercial facilities. For example, Aquamarine has employed the services of three European commercial test centers over the past year in the development of its Oyster device.

Serious Business Starts in the Tank

When it comes to ocean energy devices, testing usually initially takes place in wave tanks and/or tow tanks in order to establish the viability of the basic principles. Such testing facilities may be based on a commercial or academic basis and used to assess the performance of individual components as well as scaled down mock-up devices.

For instance, Marin is one of a group of independent maritime research institutes mainly based in Northern Europe that provide engineering, design and testing services for vessels, offshore platforms, dredgers and so on, and now more frequently ocean energy devices.

Many of these companies are members of the Hydrotesting Allliance (HTA) which aims to facilitate the world leadership of the European hydrodynamic testing facilities and is funded by the European Commission under its Sixth Framework Programme. The goal of the HTA is to develop a formal and lasting structure to co-ordinate the definition and introduction of novel measurement, observation and analysis technologies for hydrodynamic model testing environments.

The network consists of 19 member organizations from 10 European countries, including 12 major marine hydrodynamic testing facilities from such companies as Norway’s MarinTech and Qinetiq from of the UK.

Beyond Europe, North American providers of marine testing facilities include Oceanic Consulting Corp, an alliance of the National Research Council (NRC) and Memorial University of Newfoundland (MUN) based in the Canadian province at St John’s and the Offshore Technology Research Centre (OTRC) allied with Texas A&M University, with the wave basin located at the Texas A&M Research Park Campus. There is also the growing maritime testing capacity of the BRICS nations, notably Brazil and China.

However, in the specific field of marine energy, the UK not only leads the field in terms of device development, but also in dedicated marine energy testing facilities. According to Kaye, one of the reasons the UK has such advanced testing facilities is the supportive attitude of the UK government, particularly in Scotland, making the country a good place to develop in terms of support and financial access, see below.

Portugal Makes Waves of its Own

While the UK is clearly leading the pack it is far from the only show in town. Indeed, a 1:4.5 scale prototype of the Wave Dragon device, invented by Erik Friis-Madsen, was launched as early as 2003 off the coast of Denmark, at Nissum Bredning, which was the world’s first offshore grid-connected wave energy conversion device.

Elsewhere in Europe, in 2008 a 320 km2 pilot test zone off central Portugal with a capacity of up to 250 MW and dedicated to marine energy technologies was established.

Another key player in the development of Portugal’s ocean energy technology is the Wave Energy Centre (WavEC), a non-profit organization, founded in 2003. WavEC provides services to entities that intend to explore testing and demonstration of wave energy structures in the country. It also co-ordinates or participates in R&D projects to support the development of wave energy on national and international level, for example the Wavetrain2, CORES, EQUIMAR, WAVEPLAM projects.

Wavetrain was the first major European project of the WavEC, funded by the European Commission Sixth Framework Programme under the specific Marie Curie Action. The main aim of the project was to train a group of scientists in the field of wave energy. Currently, the most valuable asset of WavEC is a 400 kW Pico Oscillating Water Column (OWC) pilot plant under development in the Azores. During the five years of its existence, WavEC has gained experience in the monitoring of a number of different technologies including an AWS pilot plant of the Dutch company Teamwork Technology. Meanwhile, with its ‘Ondas de Portugal’ initiative, utility group Energias de Portugal, SA (EDP) is also supporting the establishment of a wave energy cluster, in Portugal.

One commercial project using three Pelamis units had been already installed off the west coast of Portugal at the end of 2008. With a total power capacity of 2.25 MW and a power purchase contract with the Portuguese Enersis company, technical issues relating to the location of the machine’s bearings in their housings saw the devices removed in January 2009. Another project promoted by Ente Vasco de la Energía (EVE) has the intention to integrate 16 OWC Wavegen devices into the new breakwater of Mutriku in the Basque Region with total power of 296 kW. A third project is the installation of 10 Powerbuoy devices in Cantábria, Spain with a total power capacity of 1.4 MW, in a contract with Iberdrola Renovables.

Meanwhile, Ireland’s Marine Institute, in association with Sustainable Energy Ireland, established an Ocean Energy Test Site for scaled prototypes of wave energy devices in Galway Bay, 1.6 km east of An Spideal. The Department of Communications, Marine and Natural Resources issued a foreshore lease for the site which is 37 hectares in area and is in 21–24 metres of water, in March 2006.

Oregon on a Roll with Funding

Other measures are also underway in the US that are designed to support the development of marine energy. For example, in June 2009 the New England Marine Renewable Energy Center (MREC) located at Umass Dartmouth’s Advanced Technology and Manufacturing Center (ATMC) in Massachusetts announced a $950,000 grant from the US Department of Energy. The funding will go to a consortium of researchers.

MREC director, John Miller, noted: ‘While New England suffers from energy shortages and high prices, there is tremendous energy available in the ocean at our doorstep. MREC is here to open that door bringing electricity and jobs to our region.’

The MREC consortium is currently funded by the Massachusetts Technology Collaborative and the University of Massachusetts and the centre is working with the towns of Edgartown and Nantucket to test and develop a tidal energy project in Muskeget Channel. MREC is developing a full and partial-scale test site located off the coast of Nantucket and Martha’s Vineyard that will enable developers to conduct systems trials. MREC is also working with a regional university consortium. It is anticipated that part of its development would establish a National Marine Renewable Energy Research, Development and Demonstration Center. Such a centre would support both R&D, as well as provide access to testing and demonstration infrastructure, including one or more ocean test sites pre-approved for pilot generation.

This development follows efforts by Oregon to become a national leader in the development of wave energy and which has also benefited from DOE support for the Northwest National Marine Renewable Energy Center, based at the Oregon State University (OSU) Hatfield Marine Science Center. In September 2008, the federal agency confirmed a competitively-awarded grant of $1.25 million annually, in funding that can be renewed for up to five years. This will be combined with funds from the Oregon legislature, OSU, the Oregon Wave Energy Trust, the University of Washington and other sources to create a total of $13.5 million over five years. This support will primarily be used to build a floating ‘test berth’ for wave energy technology testing on the Oregon Coast near Newport, as well as fund extensive environmental impact studies, community outreach and other initiatives. The Oregon legislature has already committed $3 million to help create the Northwest National Marine Renewable Energy Center (NNMREC). Construction of the new floating test berth should begin in 2010 and will be available on a fee basis to private industry.

Beating the Prototype Paradox

With growing interest in ocean energy technologies and the obvious opportunities that such technologies may deliver, there is a considerable push to developing testing facilities that cover the full range of requirements from theoretical and numerical modeling, through to scale wave and tow tank testing and on to full-scale prototypes installed in the harsh reality of the marine environment.

However, such testing is inevitably costly and time consuming while simultaneously, in order to raise financial backing, marine energy device developers are frequently under considerable pressure to produce a prototype that can be used to demonstrate an installation’s capabilities. Such commercial pressures increase the likelihood of the premature deployment of a device which has not been thoroughly tested and may not be sufficiently robust.

Buchner concludes: ‘I definitely see a place for [dedicated] testing centres’, also suggesting that the industry will ultimately come to mirror the oil and gas industry, and hinting at potential market consolidation over the years to come. Another emerging consideration is the development of protocols, guidelines and standards. But crucially, he warns, many system failures can be predicted by the commercial maritime industry and with three, five or even 10 metre diameter prototypes, such failures can be an extremely costly method of establishing proof of concept.

It seems that the aphorism ‘Failure to prepare is preparing to fail’ is particularly true in the ocean energy sector.

David Appleyard is associate editor of Renewable Energy World Magazine. e-mail: [email protected].


UK Marine Testing: Taking the Plunge

The UK benefits from a number of key government-backed infrastructure projects such as the European Marine Energy Centre (EMEC) on the island of Orkney off the north coast of Scotland and the New and Renewable Energy Centre (Narec) in the northeast of England, which was originally funded by One Northeast, the Regional Development Agency (RDA), but is now privately supported, as well as the Qinetiq testing facilities at Gosport, formerly part of the Ministry of Defence. Qinetiq’s Ocean Basin and Towing Tank, both of which have wave makers, are being used for testing full scale wave and tidal energy devices in controlled conditions. In addition, Voith Hydro Wavegen Limited, an Inverness-based subsidiary of Voith Hydro has a commercial testing facility open to developers. Such centres have proved invaluable in providing a test bed for prototype wave and tidal devices.

For example, EMEC is the first centre of its kind to be created anywhere in the world and it offers developers the opportunity to test full scale grid-connected prototype devices in unrivalled wave and tidal conditions. A world first was achieved when Edinburgh-based Pelamis generated electricity from its grid-connected deep water floating device at EMEC’s wave test site, located outside Stromness on the mainland. A second test site for tidal devices off the island of Eday opened in 2007, with the first developer, Dublin-based OpenHydro, already installed and exporting electricity to the grid.

In another key development, the so-called ‘Wave Hub’, an electrical offshore ‘socket’ that will allow arrays of wave energy devices to feed energy to the national grid, continues to move forward. Earlier in 2009, the government announced plans for the South West of England to become a world centre for wave and tidal energy after the region was designated the UK’s first Low Carbon Economic Area because of its strength in marine energy. The government is investing £9.5 million ($15 million) in Wave Hub and a further £10 million ($15 million) to support other marine energy projects in the South West. The Wave Hub project is now valued at £42 million, with £20 million ($30 million) of funding also secured from the European Regional Development Fund (ERDF) Convergence Programme and £12.5 million ($18.75 million) from the local RDA.

After some delay it is now expected in the water in autumn 2010, with the first device expected to be deployed in 2011.

The project off the coast of Hayle on the Cornish coast in South West England has been designed by Halcrow and it will include an onshore substation connected to electrical equipment on the seabed about 16 km offshore and in around 50 metres of water. There are four berths available at Wave Hub, each covering about two square kilometres. The device will have an initial maximum capacity of 20 MW but has been designed with the potential to scale up to some 50 MW in the future. Three wave device developers have committed to installations at Wave Hub so far.

In another move supporting Wave Hub, in July 2009, the Peninsula Research Institute for Marine Renewable Energy (PRIMaRE), set up two years ago by the Universities of Exeter and Plymouth with funding from the South West RDA, received a more than £10 million ($15 million) funding boost to support investment in new equipment, including wave and tidal measuring devices, wave making facilities, subsea electrical equipment, collision avoidance and monitoring equipment and research into the environmental impact and benefits of marine renewable energy. The bulk of the investment, £5.3 million ($8 million), has come from the ERDF Convergence Programme in Cornwall and the ERDF Competiveness Programme in the rest of the South West.

Although work on these regional marine technology centres has been underway for some time now, the impact of such developments has been increased thanks to their complementary nature, with centres like NaREC providing a testing environment for smaller prototype devices with dry docks converted for both wave and tidal technologies, while EMEC provides ‘real-world’ grid-connected test conditions for full-scale units. Once on-line Wave Hub, meanwhile, will offer the opportunity for pre-commercial testing of arrays of devices in a real environment, supplying energy to the national grid.

Indeed, Andrew Mill, chief executive of Narec explains that the UK has a full complement of testing facilities which covers the entire spread of the development cycle. For example, citing Aquamarine, Mill points to early development work at Queen’s before the company conducted fatigue testing of hoses for its Oyster I device under cyclic conditions at TUV in the Netherlands while its drivetrain systems and on shore power generation components were tested at Narec in Blyth, Northumberland. More recently, a full-scale prototype has been installed at EMEC in Orkney.