Distribution of R&D efforts for wave energy converters
The report uses the EMEC classification by which the devices are classified by their operating principle. The location at which device is designed to operate plays a role on how a WEC (wave energy converter) is classified, as well as the type of structure and foundation.
In terms of research effort, there is currently no leading category of wave energy device. The following classification according to the device type is provided by EMEC, and the distribution of the R&D efforts is given by EU’s Joint Research Centre (JRC):
Attenuators exploit the incoming wave power to generate an oscillatory motion between adjacent structural components resulting in the power take-off (PTO) activation, either by pumping high-pressure fluids through a hydraulic motor or by operating a direct drive generator.
Point absorbers are normally heaving/pitching devices that exploit the relative motion between an oscillating body and a fixed structure or component, which can be either moored to the seabed or installed on the seabed through a large foundation mass.
Oscillating wave surge converters exploit the surging motion of near-shore waves to induce the oscillatory motion of a flap in a horizontal direction.
Oscillating water columns (OWC) use the oscillatory motion of a mass of water induced by a wave in a chamber to compress air to drive an air turbine. The water column acts as a piston on the air volume, pushing it through the turbine as the waves increase the water level in the chamber, and drawing it as the water level decreases.
Bulge wave devices use wave-induced pressure to generate a bulge wave within a flexible tube. As the bulge wave travels within the device it increases in size and speed. The kinetic energy of the bulge is used to drive a turbine at the end of the tube.
Rotating mass converters exploit the relative motion of waves to induce pitching and rolling in a floating body, thus forcing the rotation of an eccentric mass contained within the device. As the mass rotates it drives an electrical generator.
The report states one of the main barriers that is slowing down the development of the sector is the lack of convergence in terms of design of wave energy converters.