If it seems like we write a lot about Scotland and marine power, that’s because no on else is pursuing this clean source of energy so aggressively. The latest step in the country’s march toward energy from the sea: An announcement that Alstom and SSE Renewables struck a deal to work together to develop a potentially giant wave power site off Orkney.
Costa Head is in the Crown Estate’s Pentland Firth and Orkney Waters Strategic Area, and the companies believe their joint venture can pull some 200 megawatts (MW) of power from the site with a vast array of wave energy converters, making it the “world’s largest wave farm.” Alstom – an energy infrastructure company that has its hands in everything from coal to wind – recently took a 40 percent stake in AWS Wave Energy, and it’s that company’s AWS-III device that’s being eyed for the Costa Head location.
The AWS-III technology consists of a multi-cell array of flexible membrane absorbers – 12 per device, typically – that convert wave power to pneumatic power through compression of air within connected cells. Turbine-generator sets then convert the pneumatic power to electricity.
These are large devices – each cell figures to measure about 50 feet wide and more than 25 feet deep – that would have a capacity of 2.5 MW. A 1:9 scale version of the device (pictured above) was tested in Loch Ness in 2010. Full-scale component testing is supposed to kick off this year, with a full-scale prototype planned for deployment at the European Marine Energy Centre in 2014.
“The selection of the AWS-III system for this exciting and ground-breaking project is a significant endorsement of our technology and team,” Simon Grey, chief executive of AWS Ocean Energy, said in a statement. “We firmly believe that the AWS-III will become the established choice for utility-scale offshore wave power generation. We look forward to working with Alstom and SSE to deliver Costa Head.”
The Costa Head site is about 3 miles north of the Orkney mainland, in waters around 200 feet deep. The plan is to slack moor the AWS-III devices “in arrays or ‘farms’ of up to several hundred MW total rating,” the companies said. The AWS-III devices will be individually connected to a central offshore substation via a high-voltage umbilical link.
But all that is a ways off. The first step for SSE Renewables and Alstom at Costa Head is to do detailed site survey, then an environmental impact assessment. After that, the aim is to develop the site in a first phase of around 10 MW, then move on to install the full site capacity.
SSE Renewables won the development rights to the Costa Head site from the Crown Estate in 2010. The company said it and and its partners are developing about half the 1.6 gigawatts of wave and tidal sites leased by the Crown Estate as part of a commercial leasing program for marine energy projects.