Plugged in and open for business15 April 2011
The pioneering Wave Hub marine energy project off the coast of Cornwall in South West England was officially opened for business at the end of last year. IWP&DC provides an update on world’s largest test site for wave energy technology
Wave Hub is a grid-connected offshore facility in South West England for the large scale testing of technologies that generate electricity from the power of the waves. Billed as the world’s largest test site for wave energy technology, it leases space to wave energy device developers and exists to support the development of marine renewable energy around the world.
The facility consists of an electrical hub on the seabed 16km off the north coast of Cornwall in South West England to which wave energy devices can be connected. The 12-tonne hub is linked to the UK’s grid network via a 25km, 1300 tonne subsea cable operating at 11kV.
The project holds a 25-year lease for eight square kilometres of sea with an excellent wave climate. Wave Hub has the necessary consents and permits for up to 20MW of wave energy generation and offers a clearly defined and fully monitored site for marine energy production.
Four separate berths are available to lease, each with a capacity of 4-5MW.
Wave Hub can readily be upgraded for up to 50MW of generating capacity in the future once suitable components for operating the cable at 33kV have been developed.
Wave Hub was first conceived in 2003 when the South West RDA (Regional Development Agency) considered which emerging renewable energy technologies would present the best opportunities for economic growth in South West England.
A panel of industry experts was brought together by RegenSW, the renewable energy agency for South West England.
Its recommendation was that the natural resources, existing skills and research capabilities in the South West were a good base for developing the emerging marine energy industry in the region.
An excellent wave climate and the available capacity in the electrical grid near the coast made the concept of a consented grid connected site for the demonstration of wave energy devices the most attractive proposition as part of a wider UK offer to the marine renewables industry.
This was followed by a scoping study to determine the feasibility of the concept, which led to a technical feasibility study that looked at options for site location, engineering considerations, legal and permitting issues and the business case for Wave Hub.
The Wave Hub itself and 25km subsea cable were manufactured by JDR Cable Systems in Hartlepool in North East England. The cable was made in one continuous length and is made up of six copper cores, 48 fibre optic cores, two layers of steel wire armouring and an outer polymer sheath. It is 16 centimetres in diameter and weighs 1,300 tonnes.
The steel hub weighs around 12 tonnes and splits the main cable into four 300m cable ‘tails’ to which groups of wave energy devices can be attached.
Offshore installation contractors CTC Marine Projects link from Darlington in County Durham handled the installation of Wave Hub and the subsea cable. This included burying the cable under the seabed for the first five kilometres offshore.
Offshore contractors Tideway from the Netherlands handled the rock dumping operation. This involved placing 80,000 tonnes of rock on the cable from around 5 kilometres offshore out to the Wave Hub site, to an average depth of around 0.5m of rock.
Powermann Ltd of Poole in Dorset handled the onshore electrical works and the new electricity sub-station at Hayle was built by Dawnus Construction.
The onshore horizontal directional drilling necessary to connect Wave Hub with the new substation was carried out by civil engineers Dean & Dyball.
Managing contractors for the Wave Hub project are JP Kenny, Staines.
The complete system underwent its first full test on 2 November 2010 when it was connected to the grid network via a new substation that has been built at Hayle, where Wave Hub’s 33kV cable comes ashore.
The penultimate stage of Wave Hub’s installation was then completed when the last of 177 concrete ‘mattresses’ were laid on top of the subsea cable. The 25km cable is buried under the seabed to around 5km offshore and thereafter has been covered with 91,000 tonnes of rock. The mattresses are being laid at regular intervals on top of the rock to ensure the cable is secure.
A marker buoy was then installed to record Wave Hub’s position, marking the final part of the physical installation.
There has been some speculation about Wave Hub’s future given that the South West RDA is due to be abolished by March 2012. However, Guy Lavender, Wave Hub’s general manager, said that the future of the project and its ongoing operation are not in doubt, with the project fully funded and commercial customers being sought.
“What we don't yet know is who will own the asset when the RDA is gone, and that is being discussed,” he said. “But that has no impact on Wave Hub's continued role as a vital facility for the development of the wave energy industry in the UK and overseas.”
Wave Hub’s first customer will be Ocean Power Technologies, using its PowerBuoy wave energy converter. In July last year, OPT’s subsidiary, Ocean Power Technologies, Ltd, was awarded a £1.5M (approximately $2.3M) grant from the SWRDA for the development of its next generation 500kW PowerBuoy wave power system.
With the new award, OPT will lead a project to accelerate the development of the technology for a larger version of its utility-scale PowerBuoy for expected deployment at the Wave Hub, sponsored by SWRDA. The anticipated collaboration among OPT, A&P Falmouth and the Peninsula Research Institute for Marine Renewable Energy, which is a collaboration between the Universities of Exeter and Plymouth (all based in the South West of England) will contribute to the scale-up of OPT's existing 150kW to 500kW PowerBuoy, as well as provide innovations to improve reliability and increase performance of the PowerBuoy.
Among the objectives of the project are prototype design enhancements for the PB500, with an expected output to power approximately 300 homes. Working with its partners, OPT will address additional areas of the PowerBuoy technology development program such as Design for Manufacture, materials research and site identification procedures. Upon completion of the project, OPT expects to bring key benefits to system delivery and market service capabilities as well as industry building and job creation in the South West of England.