The CorPower Wave Energy Converter

The resonant Wave Energy Converters developed by CorPower Ocean has a heaving buoy on the surface absorbing energy from the combined surge and heave motion of the waves. The WEC is connected to the seabed using a taut mooring line. It has a pneumatic pre-tension module between the mooring line and the buoy to enable a lightweight system with high natural frequency of oscillation. Phase control by the novel WaveSpring technology makes the system inherently resonant over a broad range of wave periods, strongly amplifying the motion and the power capture. The benefit is a significant reduction of the required buoy size compared to a conventional gravity balanced WEC without phase control, and improved survivability by the ability of detuning the device in storms.

The amplified linear motion is converted into rotation using a proprietary cascade gear box, capable of efficient conversion of linear-to-rotating motion with high durability. The cascade gear has a design principle similar to a planetary gear box, dividing a large load onto a multiple of small gears, providing high power density. Compliant elements provide damping of transient loads, making it very robust. A dual set of flywheels/generators provide power absorption and temporary energy storage for power smoothing. Generators and power electronics are standard components known from the wind industry, enabling well known grid connection architecture. The buoys operate autonomously by a programmable logic controller located inside the device, with an interface for remote control and data acquisition to shore over fibre and a radio-link.

The wave farm concept is based on combining hundreds to thousands of units in arrays, with a common grid export cable that connects the offshore wave farm to existing on-land grid. With a WEC rating of 250kW per unit in a typical Atlantic coast climate this enables 10-250MW wave farms with 40-1000 units. The concept allows mass production to drive down cost per unit and a maintenance scheme based on replacement of entire units at sea. This avoids performing service activities in the harsh offshore environment and offers improvements in farm up-time and reduction of O&M cost.

CorPower WEC features

  • Lightweight system with high natural frequency of oscillation.
  • Inherently resonant by WaveSpring control.
  • Detuned in storms, strongly reducing the loads providing good survivability up to 32m waves.

Benefits

  • 5 times higher Annual Energy / mass compared to conventional point absorbers without phase control. [MWh/ton]
  • 3 times higher Annual Energy / PTO Force compared to conventional point absorbers without phase control. [MWh / kN]
  • Low CAPEX per kW, and effective service and maintenance using a replacement scheme