Revolutionary tidal fence is set to trap the sea's power

Oxford-designed turbines aim to harness tidal energy to produce cheaper electricity - without endangering marine life.

Illustration showing how Kepler Energy’s turbine rotor blades will look installed in a tidal fence configuration
Illustration showing how Kepler Energy’s turbine rotor blades will look installed in a tidal fence configuration. Photograph: Kepler Energy

Kepler Energy, a spin-out from the Department of Engineering Science, has announced plans for an array of unique marine turbines that can operate in shallower and slower-moving water than current designs. Peter Dixon, Chairman of Kepler, said: "The turbines will in time produce electricity more cheaply than off-shore wind farms." Kepler hopes to install its new design in a tidal energy fence, one kilometre long, in the Bristol Channel at a cost of £143m."

The fence is a string of linked turbines, each of which will start generating electricity as it is completed, until the whole array is producing power. The fence’s total output is 30 megawatts (MW), and 1MW can supply around 1,000 homes in the UK.

Peter Dixon told Reuters news agency: “If we can build up to, say, 10km worth, which is a very extended fence, you’re looking at power outputs of five or six hundred megawatts. And just to visualise that, it’s like one small nuclear reactor’s worth of electricity being generated from the tides in the Bristol Channel.

The new Transverse Horizontal Axis Water Turbine (THAWT), patented by Oxford University researchers, will use the latest carbon composite technology, and should be suitable for the waters around Britain, as well as overseas.

As the turbines sit horizontally beneath the surface of the sea, they can be sited in water shallower than the 30-metre depth typically required by current designs. And because the water is slow-moving, the company says, fish can safely avoid the turbine blades.

Although the technology is regarded as environmentally benign, Kepler says it will undergo a rigorous environmental impact assessment during the planning process to ensure that it poses no significant risk to marine life and to other users of the sea.

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