Aquamarine Power – Oyster Wave Energy Generator
Challenge: traditional bearings are unusable in sea water
Solution: development of custom D-glide® bearings for this application
Together with emeritus professor Stephan Salter of the Edinburgh University, Aquamarine Power developed the ‘Oyster’ concept, for converting wave energy into electricity. The idea was to affix a large flap by means of a hinge to the sea floor, so that it is free to move. The motions would then be used to drive hydraulic cylinders creating a fluid flow that would drive an electric turbine.
With the realisation of the Oyster 800 by Aquamarine Power, one of the last remaining, virtually untouched sources of renewable energy would be activated. Using traditional bearings for the hinges was not an option. Bearings suitable for use in this application, meeting all criteria, simply do not exist.
The first major challenge in this project was the environment in which the parts needed to move: in the ocean at the location where the waves break, submerged in highly turbulent sea water, laden with sand and subjected to strong currents.
Secondly, every seven to ten seconds a wave would create a motion, which comes down to over 10.000 cycles a day, every day.
The third challenge was the sheer size of the unit: Oyster’s foreseen dimensions were 15 by 25 metres.
Besides the above, the bearings needed to transfer radial loads, axial loads, allow misalignment and axial displacements. Furthermore the bearings needed to be maintenance and lubricant free: whilst saving the planet by means of harvesting renewable energy, it is not done to pollute the ocean with lubricants.
The solution was the development of bearings using D-glide® and stainless steel, enabling this critical hinge to be realized.