Revolutionary Fence Is Set to Trap the Sea’s Power

Innovative turbines designed in the UK aim to harness tidal energy to produce cheaper electricity − without endangering marine life.

A British company has announced plans for an array of unique marine turbines that can operate in shallower and slower-moving water than current designs.

Kepler Energy, whose technology is being developed by Oxford University’s department of engineering science, says the turbines will in time produce electricity more cheaply than off-shore wind farms.

It hopes to install its new design in what is called a tidal energy fence, one kilometre long, in the Bristol Channel − an estuary dividing South Wales from the west of England − at a cost of £143m (US$222m).

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.

Power outputs
Peter Dixon, Kepler’s chairman, told Reuters news agency: “If we can build up to, say, 10 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, 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) − whose design is compared to that of a water mill − will use the latest carbon composite technology, and should be suitable for the waters around Britain, as well as overseas.

Because 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 turbines’ blades.

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