A rather unusual form of wave energy turns energy-harvesting devices in circles like a spinning top. Rotational wave energy employs an eccentric, or off-centre, weight that is sealed inside a buoy or ship hull and spins in rough seas. Finnish company Wello will soon begin testing the Penguin, a 500 kW rotational wave energy device. The Penguin has an asymmetrically shaped hull that causes it to roll, heave, and pitch – much like the stilted stride of a penguin – with each passing wave. The movement is used to accelerate a 95-tonne weight that spins inside the hull and drives an electric generator to produce electricity.
Instead of bobbing up and down, oscillating wave surge converters pitch back and forth with each passing wave. The devices consist of massive hinged flaps attached to the sea floor in shallow waters. As waves pass the device they push the flap closed. That’s how the Oyster 800, built byAquamarine Power of Edinburgh, works. But instead of generating electricity at sea, the device harnesses mechanical movement to pump pressurised water to an onshore facility. There the water drives a hydroelectric turbine that can easily be maintained from shore. Aquamarine will soon begin testing its commercial-scale device, Oyster 800, an 800 kW device that is 26 metres wide and stands 12 metres tall.
(Image: Aquamarine Power)