Numerical study on efficiency and robustness of wave energy converter-power take-off system for compressed air energy storage

The unpredictable fluctuations of wave lead to an imbalance between energy supply and demand. This article proposes a wave-driven compressed air energy storage system, which uses wave mechanical energy instead of electrical energy as the direct driving force for the compressors. Compressed air energy storage solves the problem of stability of wave energy output by accumulating and storing wave energy and then releasing it in a centralized manner. Due to the significant change in load damping compared to the generator, the damping force of the power take-off with compressed air energy storage load is analyzed. And a robust strategy with adjustable buoy draft and load compressor number is proposed, and the highest capture width ratio of 26.71 % and wave energy to compressed air energy conversion efficiency of 13.00 % are achieved under regular wave conditions. Surface seawater is used for heat supplementation in the expansion phase, and a closed-loop system is designed to avoid the damage of low-temperature condensation, the round-trip efficiency of the system is 11.26 %. This research provides a potential power generation path for wave energy and surface seawater heat. And it may beneficial to provide stable and relatively cheap power supply for coastal and offshore users.