Tidal Generation Ltd was acquired recently by Alstom from Rolls-Royce, and the marine energy device that came with the deal has now achieved power generation at the 1MW level for the first time under seagoing conditions at the European Marine Energy Centre’s (EMEC) test site in Orkney, Scotland. After the successful test of its 500kW device, this is the second of Alstom’s tidal turbines to send power to the grid.
500 kW and 1 MW variants of the tidal stream turbine had already been subject to extensive testing as part of the Energy Technologies Institute (ETI) commissioned and co-funded ReDAPT (Reliable Data Acquisition Platform for Tidal) consortium project. Detailed testing and analysis in different operational conditions off Orkney will continue throughout 2013 over an 18 month period, in order to further improve the technology. The next step is to install pilot arrays prior to full commercial production.
The device consists of a three-bladed, pitch-controlled rotor, with a diameter of 18 m, coupled to a standard drivetrain and power electronics in its nacelle. The 22m long nacelle is installed onto a separate seabed-mounted foundation and weighs less than 150 tonnes. This tidal stream turbine has a number of notable features, says Alstom. First, it is simple, and easy to transport, and its buoyancy means that it is easily installed and retrieved in a single tidal cycle using small vessels. Secondly, it has an ‘intelligent’ nacelle. Thrusters rotate the nacelle to reflect the direction of the tide, managing ebb and flood tides seamlessly as well as maximising energy production. Thirdly, with its efficient blades, turbine blade pitching can be altered to control load on the turbine and optimise use of the tidal conditions locally.