Marine Energy: Daring To Be Different

Aquamarine Power Oyster, Aquamarine’s wave energy device is designed to capture energy from near-shore waves. The system consists of a simple oscillating wave surge ‘paddle’ fitted with double acting pistons, deployed in depths of 8–16 metres. Each passing wave activates the pump which delivers high pressure water via a sub-sea pipeline to the shore. Onshore, the high-pressure water generates power using conventional Pelton wheel-type hydroelectric generators.

Following a two-year research programme, including scale-model tank testing which was also part-funded by the UK’s Carbon Trust, the company is currently planning a second Oyster wave energy project at the European Marine Energy Centre (EMEC) off Orkney in 2011 using its 2.5 MW Oyster 2 device, which features a new, more efficient shape. And, Aquamarine recently secured £5.1 million (US$7.9 million) of funding from the Marine Renewables Proving Fund (MRPF) to support its manufacture. The first full-scale 315 kW Oyster began exporting power to the National Grid in November 2009.

The Oyster 2 project will consist of three linked devices powering a single onshore hydro-electric generator. Multiple devices will share one pipeline and one onshore generator, offering efficiencies of scale.

The device has also been designed for mass manufacture, Aquamarine says, adding that it plans to deploy its first commercial Oyster by 2013. The company claims its design is unique in that it starts generating electricity in almost calm sea conditions and can continue to do so even in the worst of storms, making large-scale commercial success more achievable. Aquamarine has an agreement with part of Scottish and Southern Energy to develop sites capable of hosting 1000 MW of marine energy by 2020.

Aquamarine Power was founded in 2005 by Allan Thomson and Professor Trevor Whittaker, head of the wave power research group at Queen’s University Belfast in Northern Ireland.

Lunar Energy

In May 2009 Lunar Energy announced a trial of its Rotech Tidal Turbine (RTT), a submersible ducted turbine placed on the seabed. The commercial prototype of the RTT features a 1 MW power train which was synchronised to a simulated grid.

At the heart of the device is a horizontal axis symmetri cal turbine designed to capture and maximise the reversing currents of the oceans. Energy is provided to a generator using marine-standard hydraulic motors, a measure the company says will help generate viable low cost renewable energy.

Lunar Energy is based at Hessle, East Yorkshire in the UK and has research and development facilities in Aberdeen, Scotland.

The latest developments follow a £500 million (US$774 million) agreement with Korean Midland Power Co (KOMIPO), to supply a giant 300-turbine field in the Wando Hoenggan Water Way off the South Korean coast. The field is expected to supply 300 MW of capacity by the end of 2015. Fabrication and installation of the tidal turbines will be carried out by Hyundai Samho Heavy Industries (HSHI), while Rotech Engineering is to provide design optimisation and specialist components.

A prototype unit is also expected to be deployed at the European Marine Energy Centre (EMEC) in Orkney by mid-2010.

In addition, Lunar Energy says it has submitted a bid to the Crown Estate for the development of a demonstration field in the Pentland Firth off Scotland.

Founded in 2001, Lunar Energy developed technology along with the company Rotech Engineering Ltd, whose modular design is patent protected.

Each unit has a turbine diameter of 11.5 metres and a fully ballasted weight of more than 2500 tonnes.

Checkmate Seaenergy

A distensible rubber tube anchored to the seabed and floating just beneath the surface with its head to sea, the Checkmate Seaenergy Ltd Anaconda is continually squeezed by passing sea waves. These waves form bulges in the tube and travel down its length, developing the power to drive a turbine and generator in the stern.

Interaction of the bulge tube with the surrounding sea waves is complex and has become the subject of an Engineering and Physical Sciences Research Council grant-funded study led by Professor John Chaplin. The study is expected to result in a detailed numerical model of the bulge tube, helping to optimise tube efficiency in real sea conditions.

So far, the development programme has concentrated on proof-of-concept testing of 1:25 scale models of Anaconda in the wave tank facilities at Qinetiq’s Haslar Marine Technology Park at Gosport, UK.

In parallel with the tank testing at Haslar, the Anaconda team, with support from the Carbon Trust’s Marine Energy Accelerator programme, has been researching and developing the rubber-based technology at the heart of the device. The team has also established a small experimental water tank in the UK allowing scaled-down prototype Anaconda components to be evaluated and tested. More power output testing is scheduled for one week during mid-October 2010.

The company intends to launch a fundraising round with financial institutions and independent investors in early 2010 to allow a full engineering development programme to begin, leading to commercialisation.

Paul Auston, chairman of the Checkmate Group, said: ‘We’ve seen excellent results in scale model testing, and we are now gearing up to attract the necessary investment to develop Anaconda and take this proven concept through to full commercialisation within the next five years.’

Established in 2007, Checkmate Seaenergy holds the exclusive licence to commercialise the patented Anaconda device and is based at the site of sister company Checkmate Flexible Engineering in Melksham, Wiltshire, UK.

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Marine Current Turbines

Since starting operation in late 2008, a SeaGen unit has now exceeded 1000 hours of operation in Northern Ireland’s Strangford Lough, designers Marine Current Turbines Ltd (MCT) say. A tidal energy turbine with twin, axial flow, variable pitch 16 metre diameter rotors, the machine stands in 28 metres of water, where it is undergoing pre-commercial testing. The testing programme for SeaGen is being validated by the international marine classification society DNV (Det Norsk Veritas).

With two 600 kW turbines, the 1.2 MW tidal turbine has so far delivered some 800 MWh to the grid with an average capacity factor of 66%, MCT adds. The company has a power purchase agreement with Ireland’s ESB Independent Energy.

SeaGen has a rotor area of over 400 m2 and develops its full rated power in a flow of 2.4m/s (5 knots).

Operational from December 2008, since the autumn of 2009 SeaGen has operated automatically and without the presence of ‘marine mammal observers’ on board.

Managing director Martin Wright said the company is working towards deploying the UK’s first tidal farm during 2012. Development of SeaGen follows the installation of the 300 kW SeaFlow system, off the north Devon coast in 2004.

In February 2010, MCT secured £2.7 million (US$4.2 million) from the Carbon Trust’s Marine Renewables Proving Fund to support the company’s evaluation and operation of SeaGen as a precursor to the deployment of a tidal farm. SeaGen became the first marine renewable energy project to be accredited by the UK energy regulator Ofgem to receive ROCs (Renewable-energy Obligation Certificates) for energy generated.

In the same month MCT announced that Siemens had invested some £4.8million ($8 million) in the company, acquiring an almost 10% stake.

Following the investment round led by the Carbon Trust in 2009, this latest funding brings the total 2010 investment in Marine Current Turbines to £8.5 million ($14 million).

The total funding will help MCT in its plans to deploy the UK’s first commercial tidal energy farm in UK waters within the next two years.

The company is also partnering RWE npower renewables to develop a 10.5 MW tidal farm off Anglesey using seven machines which, it is hoped, will be commissioned around 2011-2012, and in Canada MCT is working with Minas Bay Pulp & Paper to deploy a single SeaGen device in the Bay of Fundy, Nova Scotia during 2011.

Based in Bristol, UK, Marine Current Turbines was established in 2000 and its principal corporate shareholders include BankInvest, Carbon Trust Investments, EDF Energy, ESB International, Guernsey Electricity and High Tide.

Ocean Power Technologies

Ocean Power Technologies’ (OPT’s) PowerBuoy system captures wave energy using large floating buoys anchored to the sea bed. The rising and falling of waves causes the buoy to move up and down and the resultant stroking is converted via a power take-off and electric generator inside the buoy. In the event of very large oncoming waves, the system automatically locks-up and ceases power production until wave heights return to normal. A 10 MW OPT power station would occupy approximately 30 acres (0.125 km2) of ocean space, the New Jersey, US-based company says.

Commencing in 1997, ocean trials have been conducted off the coast of New Jersey to demonstrate the concept and the company’s flagship 150 kW PB150 PowerBuoy is due for deployment at the European Marine Energy Centre (EMEC) in Scotland as REW goes to press.

Once fully demonstrated at EMEC, the company intends to install units at locations that include Reedsport in Oregon, US. The expected 1.5 MW project will be developed in two phases. The first phase will install a single PB150, plus associated underwater electrical infrastructure. (In November 2009, OPT announced the completion of trials of its Underwater Substation Pod (USP) which collects and transforms power from up to 10 buoys for transmission to shore.) The second phase will see up to another nine units installed over the next two to three years. At the same time, OPT contracted Oregon Iron Works to begin construction of the first Reedsport unit.

The move follows the signing of a memorandum of understanding for wave projects in Oregon, such as the Coos Bay Project where the company is studying the feasibility of the phased building of a station with a capacity of up to 100 MW.

OPT has also begun installation of a 1.39 MW wave farm off the northern coast of Spain in a joint venture with local utility Iberdrola SA. And, in March 2010, OPT secured €2 million of European Commission funding for a wave prediction research project, most likely at the Spanish site.

A full size demonstration plant of up to 5 MW is planned for the UK at the forthcoming Wave Hub project.

In October 2009, OPT signed an agreement with a consortium made up of Idemitsu Kosan Co., Mitsui Engineering & Shipbuilding Co., and Japan Wind Development Co. to develop a demonstration bouy system in Japan.

In February 2010, OPT announced the deployment of one of its 40 kW-rated devices at the Marine Corps Base at Kaneohe Bay on the island of Oahu in Hawaii as part of a programme with the US Navy to develop and test OPT’s wave power technology.

Oceanlinx

Australia-based Oceanlinx uses an Oscillating Water Column (OWC) design, in which ocean swells force air through an enclosure, coupled with its own patented Denniss-Auld turbine technology. Using variable pitch blades, the turbine overcomes the intrinsic problems of turbine stall associated with the bi-directional airflow of OWC systems and the company claims the design is significantly more efficient than the Wells turbine most commonly used in other OWC devices.

With no moving parts below the waterline, a commonly available generator and variable speed drive are used to convert the mechanical energy. The enclosure platforms are located offshore using a tethered arrangement similar in design to those used in the oil industry.

Testing has been underway since 2005, when the first full-scale test unit was installed at Port Kembla in New South Wales, Australia. The approximately 500 tonne Mk1 device, now decommissioned, used a parabolic wall to concentrate the wave energy into its 100 m² OWC and achieved more than 500 operational hours following a 2009 refurbishment.

Oceanlinx deployed an instrumented 1/3rd scale test unit of its Mk2 device in late 2007 and early 2008 in order to secure technical design data for its floating structures and has now begun installation of a pre-commercial Mk3 design. Destined for a shorter than normal design life, which Oceanlinx says is normally 25 years, the device is designed to verify calculated and test data for the Mk3 design in open water conditions.

Deployment is scheduled for early 2010 and the resulting grid-connected device, in which multiple OWC and turbine pairs will be installed in a single structure with an integrated control system, is expected to generate a peak power output of more than 2.5 MW. Depending on the wave climate conditions, the machine is expected to be able to generate around 1 MW on average and the company adds that its modular technology allows an array of units to connect to the same sub-sea cable or off-shore substation. The company estimates that an array Mk 3 platforms a few hundred meters across could generate several hundred MW.

In July 2009, following a call for ‘tens of millions’ of dollars of investment, Oceanlinx announced it had closed a ‘significant’ funding round with a European-based investor syndicate comprising the New Energy Fund, Espírito Santo Ventures and Emerald Technology Ventures.

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Pelamis Wave Power

The Pelamis Wave Energy Converter is a semi-submerged, articulated structure composed of cylindrical sections linked by hinged joints. The wave-induced motion of these joints is resisted by hydraulic rams, which pump high-pressure fluid through hydraulic motors via smoothing accumulators. These motors in turn drive generators. Current production machines are rated at 750 kW each, are 180 metres long and 4 metres in diameter with four power conversion modules.

Power is fed down a single umbilical cable to a junction on the sea bed. Several devices can be connected together and linked to shore through a single cable and, depending on the wave resource, machines will on average produce 25%–40% of the full rated output annually, Pelamis says.

In February 2010, the company launched the first tubes of the second generation P2 Pelamis machine under the terms of contract with utility group E.ON.

With specialist heavy-lift equipment from Mammoet, the 190 tonne tubes were moved from PWP’s fabrication hall to the nearby quayside of Leith Docks. A further three tubes are due to be launched as this article went to press (early March) and the unit is scheduled to be deployed at European Marine Energy Centre (EMEC) in Orkney, later this year. The P2 configuration allows more energy storage to be included at a lower cost, as longer individual accumulator vessels can be used, the company adds.

Also at EMEC, the planned Orcadian Wave Farm will consist of four Pelamis generators supplied to ScottishPower Renewables which will utilise existing electrical subsea cables, substation and grid connection installed in 2004, when PWP’s prototype Pelamis became the first machine at EMEC to generate to the UK grid.

In 2010 Pelamis Wave Power and project partners E.ON also secured £4.8 million (US$7.4 million) of funding from the UK government’s Marine Renewable Proving Fund (MRPF) for the P2 design.

The project with E.ON was followed in December 2009 with the creation of Aegir Wave Power Ltd, a joint venture with Swedish utility Vattenfall. The companies plan to develop a wave power project off the Shetland Islands’ west coast up to 20 MW in size and potentially using around 25 Pelamis P2 machines.

The company was founded in 1998 by Dr Richard Yemm, Dr Dave Pizer and Dr Chris Retzler with the aim of developing the Pelamis Wave Energy Converter. Since then the company has raised over £40 million ($60 million).

In addition to the forthcoming projects, Pelamis had already installed a 2.25 MW installation at Aguçadoura, 5 km off the Atlantic coastline of northern Portugal, using three P1-A Pelamis machines, although this array was subsequently removed to address issues relating to the location of the machine’s bearings.

OpenHydro

In November 2009 OpenHydro deployed its first commercial tidal turbine in Canada’s Bay of Fundy. With a diameter of 10 metres, the 1 MW open-centre machine is located in the Minas Passage at the Fundy Ocean Research Centre for Energy (FORCE) tidal test site. Part of a major contract with local utility group Nova Scotia Power, testing will last up to two years, and is focused on the robustness of the turbine, any environmental impacts, and energy production.

The 400 tonne device was lowered to its subsea gravity base — designed by OpenHydro and fabricated by Cherubini Metal Works under the terms of a CAN$1.7 million (US$1.66 million) contract awarded in April 2009— by the heavy lift barge the OpenHydro Installer, also designed and developed by the company and which it says delivers a step change in the economics of tidal energy.

An Irish energy technology company, in 2008 OpenHydro became the first to deploy a tidal turbine, with a 6 metre diameter, at the European Marine Energy Centre (EMEC) in Scotland.

April 2009 also saw a contract with publicly-owned utility Snohomish County Public Utility District. The plans envisage a project in the Admiralty Inlet region of Puget Sound, off Washington State in the US, involving up to three turbines and beginning as early as 2011.

This follows a deal with Électricité de France to develop the first tidal current demonstration farm to be connected to the French electricity grid. Under the terms of this contract, at least four and up to 10 turbines will be progressively connected from 2011.

OpenHydro has raised more than €50 million (US $69 million) since its formation in 2005 after securing world rights to the Open-Centre turbine technology in late 2004. In October 2009, the company was awarded a grant of up to €2 million under Sustainable Energy Ireland’s (SEI) Ocean Energy Prototype Research & Development Programme to support the design and development of its next generation, 16 metre open-centre turbine, subsea base and installation barge. It is also seeking to raise an extra €30 million ($41 million).

Wavedragon

Danish firm Wavedragon uses a large barrier system to channel waves to a central receiver. As waves reach the reflectors they elevate and reflect towards a doubly-curved ramp. The slack-moored energy converter of the overtopping type effectively elevates ocean waves to a reservoir above sea level, from which water is discharged through a number of low-head turbines.

Wave Dragon is constructed with chambers where a pressurized air system makes the floating height of the Wave Dragon adjustable, key to maximizing the efficiency of the device. Wave Dragon is equipped with a series of hydro turbines which individually start and stop in order to facilitate as smooth an electricity production as possible. It is designed for deployment in relatively deep water of more than 25 metres and preferably over 40 metres to take advantage of the ocean waves before they lose energy as they reach the coast, the company says.

The first 237 tonne grid-connected 1:4.5 scale prototype was deployed in Nissum Bredning, a fjord in northern Denmark, in 2003 and the €4.35 million (US$5.9 million) project secured substantial grants from the Danish Energy Authority and the European Commission as well as the Danish system operator Elkraft System’s RTD fund.

The prototype was tested continuously until January 2005 and in 2006 a modified prototype was deployed to another test site with a more energetic wave climate. The prototype features wave reflectors of 28 metres each, a 55 m3 reservoir and seven 2.3 kW Kaplan turbine-generator units, giving a maximum output of more than 16 kW. This compares with a full-scale version featuring an 8000 m3 water reservoir and in which the wave reflector would be 145 metres long.

In 2007 Wave Dragon lodged an environmental impact assessment for a 7 MW installation off the coast of Pembroke in Wales following on from a contract with KP Renewables to develop a demonstrator project. The device, covering an area of approximately 0.25 km², was to be located two to three miles (3.2–4.6 km) off St Ann’s Head and tested for three to five years. However, although the company had planned to commission in 2010 and deploy its multi-MW installation in 2011/2012, in August 2009 WaveDragon issued a statement saying that the financial crisis has caused a delay in deploying the first full-scale Wave Dragon.

The company is currently seeking venture capital, but has issued a development timetable in which it says it hopes to secure planning and other consents by the end of 2010 as well as start construction. Deployment and grid connection of the device are expected to take place during 2011–2012, the first step in establishing a more than 70 MW wave power plant in the Celtic Sea after 2012.

The company is also engaged in a 50 MW array in Portugal through its 20% holding in TecDragon.

Wave Dragon says it is ready to construct and deploy a full-scale commercial demonstration unit, adding that in a high energy wave climate, as found off the west coasts of Scotland and Ireland, one Wave Dragon unit will produce some 50 GWh per year.

Pulse Tidal

The Pulse Tidal technology is based on twin hydrofoils positioned across the tidal flow in which moving water pushes the foils either up or down according to their angle. Connecting rods join to a crank, some simple gearing and a conventional generator which are located above the waterline. Using wide, flat hydrofoils means that the blade length is not limited by water depth, a fact which Pulse claims is a key advantage of its system over rotating designs and enables the devices to be installed in relatively shallow water close to shore, yet still produce significant output.

Since completing a programme of tank testing in collaboration with the University of Hull, UK in 2005, in May 2009 the company installed a 100 kW test unit in the nearby Humber Estuary close to Immingham Dock in a £2 million (US$3.1 million) project. Output from the unit, which features four hydrofoils, is supplied directly to the large chemical works of Millennium Inorganic Chemicals, 1 km away on the south bank of the river. Mounted on two piles, the device operates in a mean water level of 9 metres and within a 4 metre tidal range.

Pulse is now engineering a 1 MW version that it says will deliver the lowest lifetime cost of power from tidal streams. The company is currently negotiating the location for its first full-scale project, which is expected to begin operations in 2012, Pulse chief executive Bob Smith says.

In December 2009 an €8 million ($11 million) grant from the EU’s technology research and development fund was awarded to Pulse and its seven supply chain partners: Bosch Rexroth, Herbosch Kiere, DNV and IT Power for engineering; Niestern Sander for construction; the Fraunhofer IWES for control and electrical systems; and Gurit for composites.

Pulse had previously raised some £2.7 million ($4.2 million) thanks to investment from Marubeni, IT Power, Life-IC and the Viking Fund, along with some individuals and government grants. And, following a £765,000 ($1.18 million) funding round in 2009, the company is now engaged in fundraising to match the EU grant, which covers 50% of the development costs of Pulse’s full-scale commercial tidal generator.

Pulse says it expects the devices to match the generation costs of offshore wind after only 100 MW has been cumulatively installed.

David Appleyard is associate editor of Renewable Energy World Magazine.

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