Aquamarine Power – Oyster Wave Energy Generator

Aquamarine Power, United Kingdom
Traditional bearings are unusable in sea water
Development of D-glide bearings for this application


Oyster Wave Energy Generator

The question
Together with emeritus professor Stephan Salter of the Edinburgh University, Aquamarine Power developed the ‘Oyster’ concept, for converting wave energy into electricity. This concept required bearings that had to meet a special combination of demands.

The situation
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.

One 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. 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, roughly the size of a 30 car carpark. Challenging too was the fact that the bearings needed to transfer radial loads, axial loads, allow misalignment and axial displacements. Obviously the bearings needed to be maintenance free, it is not done to pollute the ocean with lubricants, whilst saving the planet by means of harvesting renewable energy.

The practice
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 solution
The development of bearings using D-glide and stainless steel, enabled this critical hinge to be realized.


The result
With the realisation of the Oyster 800 by Aquamarine Power, one of the last remaining, virtually untouched sources of renewable energy was activated.