Marine current turbines work, in principle, much like submerged windmills, but driven by flowing water rather than air. They can be installed in the sea at places with high tidal current velocities, or in a few places with fast enough continuous ocean currents, to take out energy from these huge volumes of flowing water.
These flows have the major advantage of being an energy resource which is mostly as predictable as the tides that cause them, unlike wind or wave energy which respond to the more random quirks of the weather system.
The technology under development by MCT consists of twin axial flow rotors of 15m to 20m in diameter, each driving a generator via a gearbox much like a hydro-electric turbine or a wind turbine. The twin power units of each system are mounted on wing-like extensions either side of a tubular steel monopile some 3m in diameter which is set into a hole drilled into the seabed.
MCT installed SeaFlow, the world's first tidal stream device in May 2003. It is also set to install the world's first Grid-connected tidal stream device - the commercial scale prototype 1.2MW SeaGen - in March this year, to be deployed in Northern Ireland's Strangford Lough.
Artists impression of a tidal power installation
Tidal Technology
