The increasingly buoyant UK wave industry has been boosted by the Crown Estate’s award of prime acreage southwest of the Shetland Islands to the Aegir joint venture, clearing the way for the next phase of a commercial-scale development that could start flowing electricity by 2015.
Aegir — a tie-up between Swedish utility Vattenfall and Edinburgh-based Pelamis Wave Power — has plans to sail 14 750kW P2 wave-energy converters (WECs) out to the 2sq km site, roughly 10km from land, as part of a 10MW lead-off phase.
Ultimately, the development could comprise 26 of the serpentine devices, slack-moored and spaced 300 metres apart in a “daisy¬chain” to form a 20MW complex, supplying power to 26,000 homes.
Each 180-metre-long, 1,300-tonne machine would generate at 690 volts of alternating current, which would be stepped up by transformers in its nose cone and conveyed through inter-array cables to a 6.6kV export line, then on to an onshore substation, potentially at Marwick Bay.
From here, the electricity would be conveyed via a high-voltage direct-current line from Shetland to the mainland grid.
“Partnering with Vattenfall for this development has already had a wide range of benefits,” says Pelamis’ Aegir project manager, Andrew Scott.
“They have a very strong in-house capability on project development — cost management, timelines, EIA [environmental impact assessment] work and so forth — and they have a strong engineering background as well. For us [as a technology developer] it is very reassuring to be working with a company with that sort of depth of resource, competence and experience.
“Their being involved in Round 3 sites [for offshore wind developments] and the test centre off Aberdeen for offshore wind technology is key too.”
Pelamis business development director Max Carcas notes that the project is “at the heart of Vattenfall’s ocean-energy programme”.
Aegir has been pursuing the idea of a development in these waters since 2009.
The project timeline, which envisages series fabrication of the P2s starting in 2013-14, hinges on further site investigations that will inform everything from placement of the device’s mooring anchors and inter-array cabling to a better understanding of the area’s extractable power.
With the Crown Estate lease in hand, work will begin using wave-measurement buoys to determine exactly how rich the energy resource is. “How you wire up a wave farm per se will be something we are working on, along with a number of other things, including geophysical and geotechnical survey work to establish where best to place the anchors,” explains Scott.
“We are also naturally looking at the wave resource at the site as well, because we are looking at a big area with some variation of resource. Of course, you want to access the best resource, but if that comes at a cost of an extra £500,000 [$810,000] in subsea cabling, for instance, then that needs to be quantified in the micrositing to keep within the project’s economics.”
Development of the Pelamis WEC has been an exercise in juggling technological progress and commercial optimisation. In time, with the design improvements made as its device evolved from the high-profile P1 model — three of which were trialled off the coast of Portugal, near Aguçadoura — to its P2, the company has reduced the cost of building it by about 15%.
“While life is rarely smooth and straight¬forward, we feel we could cut another 15% off the cost over the course of building the next four machines,” Carcas says. “Could we do it again by building another eight? Probably could.
“Cost reduction is a mixture of learning by searching and learning by doing — this is how innovation works best. It requires a balance be struck. You can’t be changing every component with each new model, but nonetheless there is always ongoing R&D [research and development] that pushes a design ahead as it refines it.
“From the P1 machines to the P2s, we have also developed much stronger relationships with every company in our supply chain, and this helps the economics, too, in terms of potential economies of scale and improvements to the various elements of technology.”
Scotland’s Steel Engineering, which has fabricated the hulls of the first two P2s, is girding its loins to speed up production of the WEC’s cylindrical sections and various other steel structures. Parker Hannifin will be supplying the hydraulic rams, Schaeffler the bearings and ABB the generators.
The flagship P2 was installed in 50 metres of water at the European Marine Energy Centre (Emec) in Scotland’s Orkney Islands last year for utility E.ON to begin a three-year testing programme. It has performed “admirably well” so far, according to Carcas, regularly producing at average rates of 300kWh over half-hour periods in line with Pelamis’ output predictions, and showing efficiencies of 70% from power-in to electricity-out.
“Everyone is absolutely delighted about this, because wave energy is pretty tricky to work with,” says Scott. “It can go from a mega¬watt to zero and back to a megawatt in a few seconds, and you have to be able to turn that into some smooth electrical output.”
The machine is about to start claiming Renewables Obligation Certificates for its production. Full operation — with capacity factors of 25-40%, depending on the wave resource — is slated for the winter.
By the end of the summer, another P2, owned by ScottishPower Renewables, will have left its berth at Edinburgh’s Leith Docks to join its running mate at Emec.
“With these machines we are trying to de-risk the core components of the Pelamis technology, and changes that we’d expect to see at this point would be smaller ones, likely only to the universal joint, which is the bedrock of the concept,” says Scott.
Carcas adds: “Although we have had our iterations, it is fundamentally the same concept we have been working on for the past 11-12 years.”
Pelamis is involved in several front-running wave projects, any one of which could cross the finishing line first, given the unpredictability of grid connection, capital grant schemes and consenting by Scottish authorities, notes Scott. Fully developed, up to 200 Pelamis WECs could be floated out into UK waters, with a total capacity of 150MW.
“We have the Aegir project, the E.ON and ScottishPower projects, and two projects we are developing ourselves. Which one ultimately connects first may be influenced by external parameters over which we don’t have control,” he says.
“What is reassuring for us is... that even with delays and attrition, we see a good likelihood that there will be projects in a position where multi-unit supply contracts will need to be placed within the next two to three years.”
Darius Snieckus, Edinburgh