French energy infrastructure company Alstom and SSE Renewables have signed a new joint venture agreement to develop the Costa Head Wave Project, an up to 200MW wave energy site, off the coast of Orkney, Scotland.
The Costa Head site is located in water depths of 60 to 75m approximately 5km to the north of Orkney Mainland. Alstom and SSE Renewables propose to carry out detailed site surveys and an environmental impact assessment (EIA), to develop the site with an initial phase capacity of around 10MW, before moving on to install the full site capacity.
Alstom and SSE Renewables will work closely to secure necessary approvals and intend to install AWS-III wave energy converters at the site. AWS-III is a technology currently under development by AWS Ocean Energy Limited, a firm in which Alstom acquired a 40% equity share in June 2011.
The AWS-III technology consists of a multi-cell array of flexible membrane absorbers which convert wave power to pneumatic power through compression of air within cells that are inter-connected. Turbine-generator sets are provided to convert pneumatic power to electricity.
An AWS-III device will comprise an array of 12 cells, each measuring around 16m wide by 8m deep, arranged around a structure with overall beam of up to 60m. Such a device has a capacity of 2.5 MW whilst having a structural steel weight of less than 1300 tonne.
The AWS-III will be slack moored in water depths of 65 to 150m using standard mooring spreads. Devices will be arranged in arrays or ‘farms’ of up to several hundred MW total rating. Each AWS-III will be connected to a central offshore substation via a high-voltage umbilical link.