Tidal stream turbine passes small-scale test

Two British engineers have developed what they say is a breakthrough design that could, within five years, begin to generate substantial amounts of cheap electricity from deepwater tidal flows.

UK-based TidalStream reported this week that its turbine platform design — code-named Triton — successfully underwent validation testing at the deep-water test basin at Ifremer in Brittany, France. At model scale, the tests showed the Triton’s design is practical for tidal stream capture, with major advantages over other renewable energy systems, according to TidalStream.

The UK has half the tidal stream resources of the whole of Europe, the firm says. That’s the energy equivalent of several nuclear power stations, with no carbon dioxide emissions, fewer concerns over safety and at potentially lower cost.

A tidal stream turbine is adapted to deal with the density and flow rates of water, and would be located in the highly energetic channels close to shore around the north of Scotland, Ireland and England. TidalStream says its design differs from other attempts to capture power from the sea in that it can generate a large amount of power: 10 megawatts from a single installation. That means a tidal farm of just 50 Triton turbines could potentially supply the needs of over a quarter of a million homes, according to the firm.

The model tested in France was 3 metres in size, compared to a full-scale version, which would span a water depth of over 60 metres.

“Up to now, no one has managed to create a practical tidal stream system that is also at economically large size with simple access for maintenance,” said John Armstrong, one of the partners in the project. “The advantages of Triton are its size (in view of the incredible power of the sea, it’s vital to be large to create a safe working platform), and its unique “large ship” facility for maintenance access (it’s essential, for example, to be able to deal regularly with marine growth on the rotors that would otherwise degrade performance). Triton also has twice the output of the largest wind turbine yet installed offshore, so has a huge generating capacity.”

Armstrong and Michael Todman founded the TidalStream Partnership in 2005. Armstrong was previously technical director of the Wind Energy Group, while Todman was chief engineer at Rolls-Royce Industrial & Marine Power.