An affordable tidal power system deployed off the English and Welsh coasts could make a major contribution to Britain's future energy needs, say its designers. Amy Pollock reports.
Harnessing tidal energy has always been a challenge. Conventional turbines need deep waters and fast tides, which are difficult and expensive to get to. Now researchers from Oxford University have designed a tidal system they say could help meet the UK's future energy needs Working with energy company Kepler, their turbine uses a horizontal "stressed truss" design along with carbon composite hydrofoil blades, making it stronger and more enduring than conventional propeller turbines. It's also suitable for much shallower, lower velocity tidal waters. SOUNDBITE (English) GUY HOULSBY, PROFESSOR OF CIVIL ENGINEERING AT OXFORD UNIVERSITY, SAYING: "The re-design that we've done changes the blades so that they form this triangulated structure, and that's a very stiff and very strong structural form. And that means that the loads in the blades are principally carried by axial forces and that means that the stresses are much lower." The design utilises the "blockage" phenomenon to produce a head of water as the tidal waters flow past the blades, increasing the efficiency of the turbine. SOUNDBITE (English) GUY HOULSBY, PROFESSOR OF CIVIL ENGINEERING AT OXFORD UNIVERSITY, SAYING: "The water flows at right angles to the axis of the turbine so, as the turbine turns, lift is generated by these blades." The engineers have successfully stress tested their turbine twice at Newcastle University. Next Kepler proposes a $224 million one kilometre long tidal energy fence capable of creating 30 megawatts at peak performance in the UK's Bristol Channel. SOUNDBITE (English) PETER DIXON, CHAIRMAN OF KEPLER ENERGY, SAYING: "The design we have at the moment and the proposition we have at the moment is to put a tidal fence, which is a chain of these turbines in the Bristol Channel, and if we can build up to say ten kilometres worth, which is a very extended fence, you're looking at power outputs of five or six hundred megawatts and just to visualise that that's like one small nuclear reactor's worth of electricity being generated from the tides in the Bristol Channel." The developers see the system being used in shallow coastal waters around the world, off the coast of France and many Asian countries. And they forecast much lower production costs for their tidal "fence" than for the artificial lagoons created with dams and barrages in other tidal systems.