Wave energy conversion using heaving oscillator inside ship: Conceptual design, mathematical model and parametric study

Abstract

A concept of utilizing heaving oscillators inside a ship as a means of capturing wave energy is proposed, drawing inspiration from the two-body self-contained wave energy point absorber. This concept involves the ship acting as a small-amplitude-motion platform and the heaving oscillator as a large-stroke body, where the kinetic energy of their relative motion can be converted into electrical energy through a power take-off (PTO) system. The dynamic equations of the ship and the inboard heaving oscillator under regular waves are derived using the boundary element method and solved using a Python code with 4th-order Runge-Kutta integration. The numerical results exhibit favorable agreement with publicly available experimental data. Furthermore, the effects of forward speed, encounter angle, and PTO mechanical parameters on various aspects, including ship motion, oscillator response, wave energy capture performance, and inner loads, are investigated. The results show that the concept of heaving oscillator inside ship has no significantly adverse effects on the ship seakeeping performance. Both forward speed and encounter angle significantly influence the encounter period and thereby impact the sensitivity of capture width (CW) at a broader band of incident wave periods. Conversely, PTO mechanical parameters exerting a more localized impact primarily under long incident waves.