Cascade utilization of full spectrum solar energy for achieving simultaneous hydrogen production and all-day thermoelectric conversion

• Published in: Journal of energy chemistry 2024-09, Vol.96, p.318-327
• Main Authors: Zhang, Tuo, Dong, Liang, Wang, Baoyuan, Qu, Jingkuo, Ye, Xiaoyuan, Zeng, Wengao, Gao, Ze, Zhu, Bin, Zhang, Ziying, Guan, Xiangjiu, Guo, Liejin
• Format: Article
• Language: English
• Subjects: All-day operation; Hybrid solar energy conversion system; Phase change materials; Photocatalytic overall seawater splitting; Thermoelectric power generation
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2024.05.007

A novel integrated system PTC-TEG-PCM was proposed and designed for photothermal catalytic hydrogen production and 24-hour continuous thermoelectric conversion, which increased overall energy conversion efficiency by 500%. [Display omitted] Solar-driven photocatalytic water/seawater splitting holds great potential for green hydrogen production. However, the practical application is hindered by the relatively low conversion efficiency resulting from the inadequate utilization of solar spectrum with significant waste in the form of heat. Moreover, current equipment struggles to maintain all-day operation subjected to the lack of light during nighttime. Herein, a novel hybrid system integrating photothermal catalytic (PTC) reactor, thermoelectric generator (TEG), and phase change materials (PCM) was proposed and designed (named as PTC-TEG-PCM) to address these challenges and enable simultaneous overall seawater splitting and 24-hour power generation. The PTC system effectively maintains in an optimal temperature range to maximize photothermal-assisted photocatalytic hydrogen production. The TEG component recycles the low-grade waste heat for power generation, complementing the shortcoming of photocatalytic conversion and achieving cascade utilization of full-spectrum solar energy. Furthermore, exceptional thermal storage capability of PCM allow for the conversion of released heat into electricity during nighttime, contributing significantly to the overall power output and enabling PTC-TEG-PCM to operate for more than 12 h under the actual condition. Compared to traditional PTC system, the overall energy conversion efficiency of the PTC-TEG-PCM system can be increased by ∼500%, while maintaining the solar-to-hydrogen efficiency. The advancement of this novel system demonstrated that recycling waste heat from the PTC system and utilizing heat absorption/release capability of PCM for thermoelectric application are effective strategies to improve solar energy conversion. With flexible parameter designing, PTC-TEG-PCM can be applied in various scenarios, offering high efficiency, stability, and sustainability.