February 10, 2009 Bundling together the benefits of two eco-friendly forms of power generation, Scottish company Green Ocean Energy has developed a wave power machine that attaches to an offshore wind turbine.

The system, known as the Wave Treader, comprises two 20 m (66ft) long floats molded from GRP (Glass Reinforced Plastic) at ocean level attached to a wind turbine tower by 50 m (165 ft) long pivoting beams. As the floats move up and down in response to constant wave action, the arms move hydraulic cylinders attached to the beams by levers, which in turn spins a hydraulic motor connected directly to an electric generator.

Green Ocean Energy says each unit can generate up to 500 kW. As a reference the largest off shore wind turbines currently being tested generate 5MW, although most commercial off shore turbines are closer to 2 MW. It can also turn to face the direction of the wave train to ensure maximum operational efficiency. The device also has active on-board adjustments to allow for the effects of tidal range and a 25-year design life.

The Wave Treader has been developed using the core concept of a stand-alone wave power device called Ocean Treader, which is also being developed by the company. Mounting the device on the foundation of an offshore wind turbine makes that technology more commercially viable because of the relatively low technical risk. The simple design results in low manufacturing costs and it shares the power supply infrastructure with the wind turbine it is attached to.

Wave Treader is primarily aimed at Round 3 Offshore Wind Turbines, which tend to be further offshore and in more vigorous wave environments than Round 1 & 2 machines. A full size prototype could be ready for testing in 2010.

Paul Evans

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