Learn about wave and tidal projects that have generated electricity for the transmission grid

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Join us in celebrating a few of the wave and tidal technology developers throughout the world who have placed units in the water and supplied electricity to the grid.

Scotrenewables’ SR2000 unit

The ultimate goal of all the technology development work occurring in the marine and hydrokinetic industry worldwide is to get devices in the water and supplying power to the electric transmission grid. And in fact, I am pleased to report that some companies have reached that important goal. This article is intended to highlight their successes. Read on for an update on five wave and tidal technologies that have been or are in the water worldwide and have supplied electricity to the transmission grid.

Scotrenewables’ SR2000

The SR2000 2-MW tidal turbine developed by Scotrenewables Tidal Power — which is based in Kirkwall, Orkney, Scotland — has produced power at the European Marine Energy Center for more than 200 consecutive days.

The unit was first deployed at EMEC’s Fall of Warness grid-connected tidal test site in October 2016. It was retrieved in 2017 for minor repair work and was redeployed at the site in August 2017 to continue a grid-connected testing program.

Since then, the turbine has continuously generated electricity in sea states of more than 4-meter significant wave height and 2 MW of rated power in 2-meter significant waves. The SR2000 has endured wave heights in excess of 7 m. This demonstrates its capability of generating through about 99% of conditions experienced at the site, Scotrenewables says.

The deployed technology is a floating unit housing two 1-MW turbines each connected to a 16-m-diameter rotor. The SR2000 weighs about 600 tons and is 64 m long. It was designed to DNV-GL standards with a 20-year design life. Scotrenewables says this unit can be installed in water depths of more than 25 meters and can be deployed with a range of anchoring systems to suit most seabed types.

This technology has been under development since 2002, and in 2012 Scotrenewables says it achieved “a world’s first,” with its 250-kW prototype model being the first floating tidal device to export electricity to the UK grid.

The SR2000 will continue to run at EMEC through 2018. Scotrenewables is also in the detailed design phase of a production model of this technology, the SR2-2000, which incorporates a number of targeted cost-reduction innovations. This machine will be launched in 2019 for supply to the emerging global tidal energy market.

NWEI’s Azura

The Azura technology from NWEI is a multi-mode, point absorber wave energy converter. It extracts energy from both the heave (vertical) and surge (horizontal) motion of the wave, producing power from the relative motion between the hull and float. The float can rotate continuously through 360 degrees or oscillate back and forth. The float provides a self-
limiting power shedding effect, making the device survivable in open ocean environments and helping reduce loads on the mooring system, the company says. The Azura design is very low reserve buoyancy, allowing it to partially submerge under large waves. The power takeoff system is based on high-pressure hydraulics and is located within the PowerPod.

NWEI’s Azura technology

NWEI’s Azura technology

NWEI conducted a grid-connected demonstration project at the U.S. Navy’s Wave Energy Test Site at the Marine Corps Base Hawai’i in May 2015, with testing occurring for 12 months. At that time, NWEI founder and chief executive officer Steve Kopf called this “the first grid connected wave energy device in the U.S. that will be tested and validated by an independent party.”

Work on this technology began in 2006, conducted by Callaghan Innovation, and it was originally called Wave Energy Technology New Zealand or WET-NZ. After many development iterations that included wave tank testing, a pilot-scale project was completed in 2012 at the Northwest National Marine Renewable Energy Center off the coast of Oregon in the U.S.

NWEI says testing of the prototype in Hawaii was successful and a full-scale commercial unit is under development, with a possible final capacity of 1 MW.

MeyGen Phase 1A

During September 2017, Phase 1A of the MeyGen tidal stream project in the Pentland Firth provided more than 800 MWh of “predictable energy” to the grid. With this, total production at this facility surpassed 2.6 GWh.

One unit deployed at MeyGen

One unit deployed at MeyGen

This phase consists of four 1.5-MW turbines installed on gravity support structures. Each turbine is on an individual foundation weighing 250 tonnes to 350 tonnes, coupled with six ballast blocks weighing 1,200 tonnes that provide horizontal stability. Each turbine has a dedicated subsea array cable laid directly on the seabed and brought ashore via a horizontal directionally drilled borehole within the foreshore bedrock. The turbines feed into an onshore power conversion unit building.

Phase 1A incorporates two different turbine technologies. Andritz Hydro Hammerfest supplied three AH1000 MK1 units. The first of these turbines was installed in November 2016. One 1.5-MW AR1500 turbine supplied by Atlantis Resources Ltd. was reinstalled in October 2017 and brought total capacity to 6 MW.

The Crown Estate awarded an agreement for lease to MeyGen Limited in 2010, granting the option to develop a tidal stream project of up to 398 MW at an offshore site between Scotland’s northernmost coast and the island of Stroma. This site features some of the fastest-flowing water in the UK, Atlantis says.

Phase 1B will involve the deployment of an additional four 1.5-MW turbines. Phase 1C will involve building an additional 49 turbines at MeyGen with a total capacity of 73.5 MW, with installation commencing in 2019. Phases 2 and 3 should bring the project to its full permitted capacity of 398 MW.

Nova Innovation’s M100

Nova Innovation is operating a grid-connected offshore tidal array in Bluemull Sound in Shetland. In February 2017, Nova deployed the third 100-kW turbine at its Shetland Tidal Array, with the first Nova M100 turbine installed in March 2016 and the second in August 2016.

Nova Innovations’ M100 technology

Nova Innovations’ M100 technology

The company’s “plug and play” technology was installed in fewer than six days in a diver-less operation, Nova says. It is a modular system, meaning it can be transported and installed around the world using standard containers.

Each tidal turbine consists of a cylindrical nacelle component, rotor and gravity base to lock it to the sea bed. The negatively buoyant nacelle is securely linked to the base by the means of a latching system. The devices are bottom mounted, gravity anchored, non-yawing, horizontal axis tidal turbines. The turbine has a rotor diameter of 10 m and a hub height of 9 m.

At Bluemull, the devices are mounted in water depths greater than 30 m, providing clearance of more than 15 m below mean tide. The footprint of each device is 13.5 m by 12.2 m and the weight in water is 80 tonnes.

Nova is leading a project, called Enabling Future Arrays in Tidal (EnFAIT), that will involve extending the existing operational tidal array off the Shetland Islands to six turbines and study the optimization of tidal turbine arrays. The turbines will be repositioned to determine the optimal positioning to allow the units to operate most efficiently.

BPS’ bioWAVE

The Port Fairy Pilot Wave Energy Project near Port Fairy, Victoria, Australia, involved the design, construction, installation and testing of a full-scale bioWAVE pilot plant with a 250-kW O-Drive module.

BPS’ bioWAVE unit

BPS’ bioWAVE unit

Operation and testing occurred during 2017, with the project grid-connected for up to 12 months.

The bioWAVE is a submerged structure that sways back and forth beneath ocean swell waves. The unit is mounted to the seafloor, with a pivot axis near the bottom. Passing waves impart large hydrodynamic forces on the air-filled cylinder structures. The energy absorbed is converted to electricity by the onboard self-contained O-Drive module. Each bioWAVE is several stories high and has a capacity of up to 250 kW.

The O-Drive is a standardized power conversion module for wave energy projects. It is designed to be compatible with most wave energy device concepts and is being developed as a plug-and-play solution for converting the mechanical energy absorbed from the waves into grid-quality electricity.

The bioWAVE unit used was constructed during 2014 and 2015, and project installation was completed during 2015 and 2016. This included the onshore equipment, subsea cable, bioWAVE unit and O-Drive. A new cable was installed in February 2017 after the previous cable was damaged in 2016.
Data acquired from the project and experience gained is being used in further commercialization of the bioWAVE and O-Drive technologies.

Elizabeth Ingram is managing editor of Hydro Review.

Face-to-face learning

Two events provide opportunities to learn more about what’s going on the marine and hydrokinetic energy market, in person.

Waterpower Week in Washington, which takes place April 30 through May 2, features the International Marine Renewable Energy Conference and the Marine Energy Technology Symposium. IMREC features six sessions on such topics as matching MHK value to utility and grid needs of the future and attracting investment for a marine energy project. METS features technical paper and poster presentations on a variety of topics of particular interest to this industry.

In addition, HydroVision International features an entire conference track on Marine and Hydrokinetic Energy. This event takes place June 25 to 28 in Charlotte, N.C., U.S. Visit http://bit.ly/2I3ZkVD for more information on the sessions, which cover power conditioning, supply chain issues, finding financing and much more.

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