JV established to decommission tidal turbine

Scotland’s Ocean Kinetics and London-based Green Marine UK have set up a joint venture to undertake the decommissioning of the OpenHydro tidal energy platform in the Orkney Islands.

Dublin-based OpenHydro, established in 2005, was the first developer to use the European Marine Energy Centre (EMEC) tidal test centre at the Fall of Warness site in the Orkneys. Its tidal energy platform was installed there in 2006.

However, tidal power has proved to be less efficient than other offshore energy sources, and work is now proceeding to remove the steel superstructure that is attached to two piles, which are drilled and grouted into the seabed. The turbine component was fixed to the piles with two steel collars, allowing the unit to be moved up and down using two 15-tonne hydraulic winches.

The decommissioning involves removal of the superstructure and the diamond-wire cutting of the piles level with the seabed, as required upon decommissioning by the facility’s Marine License. Both have experience in relevant engineering projects, including the handling of subsea servers, port gates, aquaculture equipment, and sunken barges of up to 1,000 tonnes in weight. They also worked on the decommissioning of the Buchan Alpha drilling platform.

For the OpenHydro project, the partners are providing a range of services. Ocean Kinetics is supplying divers, riggers, welders, and remotely operated vehicle services. Green Marine is supplying offshore management, the Green Isle, a Damen 2712 Multicat workboat, as well as moorings and operational cable experience. To complete the final stages of the project, the vessel will be spread-moored in a four-point configuration, ensuring that it can remain stationary and allow safe diver operations.

Revealing that the topside infrastructure has now been removed, Green Marine operations manager, Terry Norquay, said: “The OpenHydro project has demanded a strong understanding of operations within harsh marine environments combined with solid preparation and execution. While Green Marine and Ocean Kinetics offer a broad range of marine services, this particular job demonstrates the turnkey solution we offer specifically for subsea superstructure removal projects.”

Roger Goudie, Ocean Kinetics’ marine project manager, commented: "This project cements Ocean Kinetic’s status as a leader of offshore decommissioning works. Our experienced rope-access-trained decommissioning team have worked alongside the Green Marine crew to safely deconstruct the topside structures and prepare the piles for removal. We have also had our dive team working on-site, which proves the skills offered by Ocean Kinetics given the tidal nature of the site."