On providing a reaction for efficient wave energy absorption by floating devices

Abstract This paper investigates possible use of a heave/surge compensated on-board platform (block) to enable and optimize energy absorption by deep-water floating wave energy devices. The block forms one of the masses in a system of coupled, controlled oscillators. In the absence of control, favorable dynamic interaction leads to isolation of the block from hull heave or surge at one frequency, whereas control can extend this behavior to a range of frequencies. The paper presents a frequency-domain solution for an optimal power absorption problem of a single-mode floating device utilizing such a system. Results are used to address the more complicated problem of optimal power absorption by floating oscillating water column devices. Calculations based on published results for one such device are carried out in the frequency domain for four different situations representing various degrees of compromises to optimality. Conclusions on the effectiveness of the proposed system are drawn based on comparisons, and areas needing further work are pointed out.