Underwater turbines set to generate record power

Underwater turbines set to generate record power

19:15 21 August 2007
NewScientist.com news service
Kurt Kleiner

By the end of the year, twin underwater turbines should be generating 1.2 megawatts of electricity off the coast of Northern Ireland in a landmark demonstration of tidal power technology. Marine Current Turbines, a company based in Bristol, UK, had hoped to begin installing the turbines at Strangford Lough (Google map) on Monday, but the construction barge scheduled to deliver the turbines was delayed. A company spokesman says the installation will now take place later in 2007. It will be the world's largest tidal power project. The underwater turbines look and work very much like wind power turbines. Each blade is 15 to 20 metres across and is mounted on an axis that attaches to a 3-metre-wide pile driven into the seabed.

Tide-driven currents will move the rotors at speeds of between 10 and 20 revolutions per minute, which the company claims is too slow to affect marine life. The turbines will drive a gearbox that will, in turn, drive an electric generator and the resulting electricity will be transmitted to the shore via an underwater cable. The Strangford Lough tidal generator is intended purely as a demonstration project. Eventually, MCT intends to build farms of turbines consisting of 10 to 20 pairs each. Each turbine requires a piece of equipment called a jack-up barge for installation. The barge anchors itself to the sea floor and drills a hole that sets the turbines in place. "Of the 60-odd [tidal power] projects I've seen, this seems like the best," says Dave Elliott , a professor in technology policy at the Open University in Milton Keynes, UK."It's an interesting period," Elliott adds. "You have lots of approaches andlots of innovative projects. The straightforward underwater propeller seems like the winner.

Elliott says that tidal and wave power could eventually provide between 15% and
20% of the UK's electricity needs. But he believes that operators need
to develop experience with the technology before the price of energy
generated in this way falls to levels comparable to wind power.