The Oyster and the Anaconda — A Story of Waves and Tides

The Oyster and the Anaconda is not one of Grimm’s fairy tales, or an Edward Lear nonsense story. Neither grim or nonsense, the Oyster and the Anaconda herald the good news that wave-powered and tidal-powered generation devices are well on the way to becoming commercially viable.

In the swirling waters off the shores of Orkney, in the far north of Scotland, a dozen bizarre-looking experimental devices have been deployed by The European Marine Energy Centre at Stromness in its quest  to convert the power of the sea into reliable electric power generation.

The  “Oyster” is a giant mechanical flap about 40 feet high which swings back and forth with the waves. When submerged the wave movement compresses hydraulic pumps which force water through a pipe to a generator located onshore. Manufacturer Aquamarine Power hopes to set up farms of Oysters, which in a group of three can generate 2 MW of power. In theory, some 1,500 Oysters could yield 1 GW of power,  the equivalent energy production of a typical coal-burning power plant.

The Anaconda (or more correctly the Anaconda Wave Energy Converter) is a giant rubber snake, made of a composite of fabric and natural rubber with a turbine in its tail. Submerged in the sea it converts tidal motion into electrical power. While test devices are only nine meters long  its developer (Checkmate Seaenergy) envisions a full-scale device up to 200 meters in length, capable of producing 1 MW of power (enough for 1,000 homes) for the construction cost of £2 million. In principle a farm of 50 snakes, in a tidal race a few miles offshore, could reliably power a nearby town of 50,000 homes).

Harnessing tidal power is an ancient concept. Tide mills date back to Roman times, and operated much like windmills, but with the tide rather than the wind powering the turning a wheel that rotated a millstone that ground grain into flour. Augustinian Canons operated one in Woodbridge in the east of England in the 12th century. (I visited the surviving Woodbridge mill a few years ago. An all-wooden construction, it was operating commercially as a flour mill as late as 1957. It is now a museum). By the 18th and 19th centuries there were as many as 750 tide mills operating on both sides of the Atlantic, with about 300 in North America, 200 in the UK and Ireland, and 100 in France.

Recent advances in tidal turbine technology (a byproduct of wind turbine development) hold out the promise of using large-scale turbine arrays in high-velocity areas where natural and strong tidal current flows are concentrated — such as the coasts of Canada, the Straits of Gibraltar, and the Bosporus Straits — to generate significant power.

The Oyster and the Anaconda went to sea in a beautiful………..

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Photo by Irargerich, used under a Creative Commons license.