Tidal pilot set for installation

Siemens and technology developer Flumill have set the seal on the final design of what promises to be the first full-scale tidal turbine deployed off Norway.

Installation of the 2MW twin-corkscrew design - which draws power out of the water as currents move up spiral glass-reinforced plastic rotors to turn a gearless permanent­ magnet generator - is the “next and last step” before commercialisation of the technology.

“During the FEED [front end engineering design] study we have developed a thorough insight [into] and understanding of the innovative Flumill tidal technology and we are looking forward to the continued co-operation to further develop the pilot project in Rystraumen and future commercial project,” says Siemens sales director Haakon Rem.

The grid-connected pilot unit, being fixed to the seabed near the northern Norwegian town of Tromsø, will measure eight metres in diameter and 38 metres long.

The concept is based on a design adapted from excess-flow valves in gas-distribution systems. Because its turbines rotate in opposite directions, the device is hydrodynamically stable, allowing for easy towing to site and early kick-in in streams slower than one metre per second.

Siemens has supplied electrical subsea connection equipment designed to streamline installation.

A one-quarter scale version of the Flumill design has been put through its paces at the European Marine Energy Centre’s Shapinsay Sound technology “nursery” in the Scottish Orkney Islands.

The FEED has led to “a few key design optimisations” to improve direct cooling of the gear and generator by the surrounding seawater, eliminating the need for active subsea auxiliary systems.

Siemens and Flumill have a concession for the pilot from Norwegian Water Directorate NVE and a grid connection agreement with local utility Troms Kraft.

The pilot is supported by the Norwegian government through the renewable funds Enova and Innovation Norway.

In 2012, Siemens took over UK tidal-power company Marine Current Turbines, which had been running its 1.2MW SeaGen demonstration turbine in Northern Ireland’s Strangford Lough since November 2008, with plans under way to develop the 8MW Kyle Rhea project in Scotland and the 10MW Anglesey Skerries project in Wales, as well as installing a three-headed SeaGen S machine in Canada’s Bay of Fundy.