Cornwall's Wave Hub about to switch on

The UK's first ever wave farm is expected to start supplying electricity to the national grid by 2018, thanks to substantial European funding.

The experimental Wave Hub renewable energy test site off the north coast of Cornwall is about to host its first commercial operation after an Australian-based company announced plans to construct and operate a wave farm there. Initially generating 1MW of energy per year, the annual output is due to rise to 15MW per year by 2020; enough to power 6000 homes.

Carnegie Wave Energy Ltd has been awarded a grant of £9.55m from the European Regional Development Fund (ERDF) and Cornwall Council, which has itself received £14m of funding to take over the administration of the wave hub from the UK government as part of a newly established low carbon Enterprise Zone in the far west of England.

Cornwall’s Wave Hub is claimed to be “the world’s largest and most technologically advanced site for the testing and development of offshore renewable energy technology”, and the prospect of receiving capital support grants has attracted interest from a range of overseas companies. Three berths at Wave Hub have been assigned to wave generators from Carnegie, the UK-based Seatricity and the Finnish company Forum. A fourth berth could be used for testing offshore floating wind generators.

The funding awarded to Carnegie will help them cover the costs of the construction, installation and operation of a single 1MW wave energy converter device. Carnegie has already proven the efficacy of its design with the world’s first grid-connected wave energy array on Garden Island, Western Australia. Its patented 20m diameter CETO buoys, resembling large circular tanks, are anchored to the seafloor and remain fully submerged. The rise and fall of the waves drives a pump attached to a tether. In the next-generation CETO 6 buoys, a system contained inside the tank will convert the pressurised fluid into clean electricity, which is carried onshore by a cable.

The company has stated that its project will commence immediately, with commissioning in 2018, followed by 12 months of operations. Phase 2, planned for 2020/21, will deliver a subsequent 15MW commercial array, offering the chance of a return on their total investment which is likely to exceed £60m.

The Hub is a test bed site providing a subsea socket, cable and shoreside infrastructure to connect to the national grid and which can handle arrays of up to four kinds of wave energy converters. The subsea construction and installation of the 'socket' and a 25km, 33kV rated submarine export cable was completed in 2010.

The test site measures 1950m (West) x 3950m (North), with water depths across the site range from a maximum of 57m below LAT, in the north-western corner to approximately 51.0 below LAT in the south-east corner. The offshore site is well clear of main shipping routes and is marked by North and South Cardinal Marks – Wave Hub NW and Wave Hub SE - both offset from the site. Wave Hub NW is also an AIS station. Four Special Marks with GPS synchronised lights are placed near the four corners of the site. The Wave Hub itself (export cable to cable tails seabed junction) is found at the centre of a consented 500m Radius Wave Hub Safety Zone in the south west of the site

The Hub is sited in the Celtic Sea approximately 16km off Hayle, where the Atlantic swell generates productive wave energy. Maintenance vessels and small operations craft work out of the local ports of Hayle, St Ives and Padstow, but the south coast town of Falmouth is the closest major port, containing several companies with the expertise and experience to provide research, construction and manufacturing facilities, personnel, infrastructure and dive support to the project.

The first device to be plugged into the Wave Hub was Seatricity's Oceanus 2, installed in June 2014. This full scale wave energy converter sits on the surface, and rather than charging a generator on site, their system pressurises seawater which is then pumped ashore to generate electricity in a more accessible environment. The second of two prototypes, it was constructed by A&P at Falmouth. Seatricity plans to connect 60 similar devices in a plan to create 10MW of power.

Another totally different system that has been trialled at Wave Hub is the Wello Penguin, an asymmetrical floating pontoon device which sits on the surface and has been designed to be as unstable as possible so that it is in perpetual motion as it responds to the wave action. The first of three proposed units was due to be deployed in 2016 following a three-year testing programme in Orkney. Wello Oy is a Finnish company working with Green Marine, Fortum Corporation, Mojo Maritime, Uppsala University, Plymouth University and the University of Exeter, partners in the CEFOW project (Clean Energy From Clean Waves)

One principal marine contractor with long experience of experimental projects since the early days of wave and tidal renewables is KML, which has been involved since 2008 in the installation and decommissioning of subsea infrastructure at the first wave test sites in Orkney, Falmouth and Wave Hub. Diccon Rogers of KML emphasises that wave power generation is in its infancy with pre-commercial prototypes being tested by various developers. He points out that offshore oil and gas and offshore wind took some years to become commercially viable and that Wave Hub is playing a key role in the commercialisation of these new technologies.

Going forward, it is not unreasonable to imagine that wave, tidal, solar and floating wind generators might be installed together on one site.