Deep Green turbine

The turbine complements the first full-scale Deep Green device. The underwater power plant will be deployed in 2017 at the Holyhead Deep site off the coast of Anglesey, Wales. During the coming three years, 19 more devices will follow and eventually form an array with an overall capacity of 10 MW.

Deep Green is the first device, which allows the harvesting of tidal energy in slower waters which have been thought unproductive so far – with low current velocity of two meters per second and in great depth of 60 to 120 meters.

Deep Green resembles an underwater kite and consists of a wing and a turbine. The kite has a wingspan of 12 metres and is attached by a tether to the sea bed. It moves along a preprogrammed figure-of-8-shaped trajectory and thus increases the water current velocity around the kite by its own speedy movements.

For Minesto, Schottel Hydro has developed a new turbine variant, which will optimally fit the requirements of Deep Green: The light weight nacelle power-take-off system includes turbine, drive train, power electrics and auxiliary devices. All components will be tailor-made to fit the electric system of the kite perfectly.

The drive train concept is based upon the proven concept of the Schottel Instream Turbine (SIT) with its inline arrangement of open rotor, rotor shaft including sealing and bearing, planetary gearbox and generator. In contrast to this readily available device with rotor diameters between three and five metres the Deep Green turbine will be significantly smaller and operate at higher rpms.

In addition to the turbine engineering and manufacturing, Schottel Hydro will also carry out a full-load test series on a specially built test stand prior to installing the turbine in the third quarter of 2016.

By Jake Frith