Efficient and adaptive hydrogen production via integrated full-Spectrum solar energy and solid oxide electrolysis cells with thermal storage

The integration of full-spectrum solar energy utilization with solid oxide electrolysis cells (SOECs) offer a promising solution for efficient hydrogen production. However, two significant challenges hinder the development of this technology: firstly, the discrepancy between the supply ratio of heat and electricity from solar energy and the demand ratio of heat and electricity for SOECs, and secondly, the conflict between the fluctuations in solar energy and the limited temperature fluctuation tolerance of SOECs. In this study, an SOEC hydrogen production system with thermal storage module is proposed to address these challenges. Solar energy is divided based on wavelength: shorter-wavelength sunlight is converted into electricity via photovoltaic cells, longer-wavelength sunlight is converted into heat in the reactor. The reactor suppresses temperature fluctuations by storing and releasing solar extra heat. During daylight hours, the system utilizes all the solar electricity and part of the solar heat to produce hydrogen. While at night, the system shifts to rely on grid power and stored solar heat for continued operation, thus recovering the otherwise lost solar heat and avoiding additional power consumption, and enhancing system efficiency. Thermodynamic evaluation shows that the system achieves an efficiency of 54.0 %, considering both grid electricity and solar energy inputs, which is relative 9.8 % higher than the traditional full-spectrum solar hydrogen production system. Additionally, compared to the traditional system, our proposed approach reduces grid power consumption by 26.6 % and increases solar energy utilization efficiency by 18.5 %. These findings underscore the viability and potential of the integrated system in enhancing hydrogen production efficiency while effectively managing solar energy fluctuations.