Photothermal catalytic hydrogen production coupled with thermoelectric waste heat utilization and thermal energy storage for continuous power generation

Photothermal catalytic water splitting is a potential way to produce renewable hydrogen. However, low-grade heat converted from solar energy in the photochemical process is inevitably dissipated to the environment and often wasted. Besides, the intermittency of solar energy causes the devices unable to work continuously. Here, a novel integrated solar to hydrogen-electricity and thermal storage system (STHET) is proposed to solve above problems. STHET consists of a photothermal catalytic system and a thermoelectric generator (TEG) system, which can realize hydrogen-electricity co-production and thermal self-storage. Photothermal effect in STHET is increased by recycling scattered light, leading to an enhancement of 22.7% in hydrogen production than the traditional system without TEG. Meanwhile, the maximum power of waste heat utilization by TEG is 193.53 μW. Furthermore, since strengthened heat exchange in STHET with forced cooling, the output power of TEG can improve to 1578.13 μW, and hydrogen production is reduced by only 1.4% than the traditional system without TEG. Additionally, STHET can continuously generate power using stored thermal by the liquid reaction system to achieve continuous working in the dark, in which 19% (maximum proportion) of the electrical energy output can be obtained at night. The heat exchange methods in STHET can be flexibly selected according to the requirement for hydrogen energy and electric power. As a conceptual model, STHET can also be promoted in other solid-liquid reaction systems.