Support for DeltaStream device
Innovative tidal energy projects that promise much for the future are reliant on their supply and deployment strategy.
Keynvor Morlift (KML) has been working on a number of these developments, including Tidal Energy Ltd’s DeltaStream prototype, Wales’ first full-scale tidal turbine.
Deployment, KML tells MJ, will take place this summer at Pembroke Port, but it won’t end there as the company, beyond installing the turbine, will also have responsibility for maintenance through its 12 month trial.
KML have a history of tidal energy support going back to 2008, involving lifts of control devices, powertrains and complete turbines – often in fast moving, challenging waters. More recently the summer of 2012 saw it involved in the installation of Tidal Turbine’s 1MW unit at the EMEC Tidal Test Site in Orkney, using its BD6074 crane barge, the 30m installation and support vessel Severn Sea and the company’s Cougar ROV. This is an effective combination: the multipurpose vessel has twin Volvo 1,000hp engines, a 400hp azimuthing Schottle thrusters plus a 150hp thrusters unit at bow and stern along with DP capability. It has a launch and recovery frame for the ROV and its 36 tonne and 19 tonne cranes are complemented by the crane barge’s fully slewing pedestal crane which gives 150 tonnes at an outreach of 20m.
However, this Ramsey Sound device is a little different to previous units as the DeltaStream aims to reduce installation and maintenance costs, a concern with many designs. So, instead of a piled foundation, a large triangular steel base frame will be placed on the seabed, rock footings secure the device providing a gravity foundation for three nacelles. An independent horizontal-axis water turbine generator in each nacelle is supported on a tower at the apexes of the triangular main base.
It’s an interesting utilisation of the scoured seabed that tidal streams tend to create and may yet mean that tidal devices achieve certain economies that have eluded pile foundation renewables.
However, all this means that the KML deployment will be in the limelight: if everything goes smoothly it will add weight to the argument for take up of the DeltaStream device.
By Stevie Knight
