Wave power extraction analysis of a floating hybrid wave energy converter placed over an undulated seabed using hybrid boundary element method

This study investigates the power extraction performance of a novel nearshore hybrid floating wave energy converter that integrates a piezoelectric device with a pile-supported oscillating water column deployed over an undulated seabed under regular and irregular waves. The physical problem is modeled under linear water wave theory and solved using a hybrid numerical approach that integrates the eigenfunction expansion, boundary element, and finite-difference methods, enabling comprehensive analysis of standalone and hybrid wave energy converters across various configurations and edge conditions. The optimal damping coefficient is further evaluated to elucidate the power take-off dynamics of the oscillating water column device under resonance and maximum energy extraction conditions. The study found that the hybrid system exhibits superior power extraction compared to standalone piezoelectric and oscillating water column devices, particularly in long and intermediate wave regimes, achieved through optimized parameters including moderate chamber width and height, shallow submergence depth of the piezoelectric device, and calibrated power take-off damping for resonance conditions. Notably, the free-edge piezoelectric configurations paired with compact oscillating water column chambers demonstrate maximum energy capture and resonance bandwidth. Additionally, the fixed-edge setups coupled with seabed undulations enhance stability and power output. Under realistic sea conditions represented by the JONSWAP spectrum, sea state 2 demonstrates superior wave power capture due to higher spectral energy density. Among the configurations, the fixed-edge piezoelectric device floated over an undulated seabed delivers the highest overall energy conversion efficiency and consistent resonance behavior. Overall, the findings confirm the effectiveness of hybrid wave energy converters in optimizing energy capture and structural response for reliable nearshore wave power generation.