Power generation and wave attenuation of a hybrid system involving a heaving cylindrical wave energy converter in front of a parabolic breakwater

Deploying a cylindrical heaving wave energy converter (WEC) in front of a parabolic breakwater forms a basic module for synergetic coast protection and power generation. The interactions in the hybrid system are important to its performance but poorly understood. Here the power amplification effect of the parabolic breakwater on the WEC and the additional wave attenuation effect of the WEC on the parabolic breakwater are investigated based on the potential flow theory of linear regular waves. A parabolic breakwater and five WECs with optimized geometry and generator parameters are employed in comparative numerical studies conducted using an open-source code HAMS. Results show that the parabolic breakwater has similar power amplification effects on different WECs, despite the significant differences in their dimensions and power-take-off damping. The power of a WEC can be increased by more than 120% at its natural period. A WEC can shadow the region behind it and reduce the wave amplitude on the opening wall of the parabolic breakwater. It also slightly reduces the amplitude of the relatively high waves in the protection zone behind the breakwater. A flatter WEC with a larger diameter-to-draft ratio is recommended as it generates more power and has a stronger shadow effect.