High-efficient built-in wave energy harvesting technology: From laboratory to open ocean test

• Published in: Applied energy 2022-09, Vol.322, p.119498, Article 119498
• Main Authors: Li, Yunfei, Ma, Xin, Tang, Tianyi, Zha, Fusheng, Chen, Zhaohui, Liu, Huicong, Sun, Lining
• Format: Article
• Language: English
• Subjects: Self-powered sensing; Self-sustained ocean observing platform; Wave energy harvesting
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2022.119498

•A high-efficient built-in wave energy harvesting system is proposed for ocean observations.•The power output of the system is 1–2 orders of magnitude higher than previously reported ones.•The system fully integrated with the buoy succeeded in a 4-month test in the Northwest Pacific.•This work provides a promising energy solution of self-sustained ocean observations. The ocean contains a huge amount of renewable energy. There is a tremendous need to develop new ocean energy harvesting technology for long-term and self-sustained global ocean observation. Herein, an omnidirectional and high-efficient built-in wave energy harvesting (WEH) system fully integrated in ocean observing platform is introduced, realizing energy harvesting and self-powered ocean-wave sensing, simultaneously. Based on the chaotic pendulum design and high-efficient electromagnetic coupling effect, the high output power of 520 mW and power density of 0.66 mW/cm3 have been achieved under ultra-low-frequency wave excitation with wave height of 20 cm and period of 1 s, which is extremely higher than most of the reported ones. More significantly, the built-in WEH system was fully integrated with the buoy and successfully completed the offshore test in the Yellow Sea for one month and open ocean test in the Kuroshio Extension (KE) region of Northwestern Pacific for four months. During the offshore test, the working time of an autonomous positioning sensor of the buoy was significant extended from 10 to 25 days, which is 2.5 times longer. During the open ocean test, the built-in WEH system was able to long-term survive in the Kuroshio Extension, which is one of the most dynamically-complex regions in the global ocean. The maximum and averaged output power of 210 and 24.5 mW, respectively, have been achieved, under the ocean wave heights and periods varying from 0.4 to 2.2 m and from 4.2 to 7.2 s. Meanwhile, the generated voltage data can be transmitted via Iridium Satellite and utilized for evaluating and sensing the real-time wave conditions, i.e., wave height and period. It comes to an encouraging conclusion that the built-in WEH system cannot only harvest sufficient energy to extend the service life of ocean observing platform, but also as a self-powered wave sensor to assist ocean monitoring. This work shows a promising milestone in WEH technology from laboratory prototype to practical open ocean application.