Electricity generation from tidal stream has the big advantage that the output can be reliably predicted even though the strength of the tidal stream varies throughout the day. Various designs are being developed including propeller blades driving a generator (an underwater wind turbine), aerilon shaped wings that move up and down, and sets of sails turning on a conveyor.
South west focus
The South West has some of the best tidal stream resources in the UK.The two best areas of tidal resource are in the Bristol Channel, where there is a large area of tidal stream although somewhat shallow, and off Portland Bill, Dorset where there are fast currents but the flow pattern is complex.
The first commercial sited tidal stream generator was installed 1 km off Lynmouth, North Devon by Marine Current Turbines. This prototype single rotor 300 kW machine has been in operation successfully since May 2003, and although not connected to the electricity grid, has generated electricity reliably. MCT is seeking consents to install an array of up to 10 twin-rotor generators at the same location in the future.
Marine Current Turbines' website
