The Sloped IPS Buoy wave energy device

From left:

  1. The shape of the sloped IPS concept
  2. The new model in the curved wave tank
  3. An underwater view of the new model
  4. A same model with constraint rods instead in place of the slope plate

Back in the 70s and early 80s most groups that were active in developing wave energy devices were trying to design very large scale systems. In the UK, this was virtually a condition of Department of Industry, and later Department of Energy, funding. The bottom line was always the cost per kilowatt hour of electricity from wave energy systems with electrical ratings of several gigawatts..

The Edinburgh duck is one of the best known of these devices and because of its promising delivered energy costs, it is still a potential future wave energy device. However its operation was always predicated on several technologies which were relatively young - such as hydraulic transmission components having very high efficiencies even at part load and very large area low-pressure bearings.


  The duck: An early impression of a gigawatt scale system. From the glorious days before real artists were displaced by solid model software.
  Chiapo Lin with his constrained model of the sloped IPS buoy.  
  The new dynamometers for the free floating model  
  During the 90s, with increasing concern over global warming, there was a resurgence of interest in wave energy. This was backed up by funding from Europe and more recently from within the UK. There was a clearer need to look at the development of more modest systems. We had been testing models of various 'solo' devices and then realised that the Swedish IPS buoy concept had a particularly attractive feature - an elegant solution to the 'end-stop problem'. We were interested to see if we could take their idea, and by modifying the primary angle of operation, make it more productive - the so called 'sloped IPS buoy'. In the course of his doctorate work, Chiapo Lin, showed that we had reason to be optimistic about the effect of slope on performance. An EPSRC funded programme helped us to further investigate this device.  


Wide tank efficiency measurements on a model of the sloped IPS Buoy (artificially constrained model).

The design of an eddy current dynamometer for a free-floating sloped IPS buoy