Glycerol-assisted co-electrolysis in solid oxide electrolyzer cell (SOEC) for green syngas production : a 2D modelling study

Abstract

A 2D multi-physics model is developed to study the glycerol-assisted SOEC co-electrolysis process, with a novel in-tube reformer to improve the fuel utilization and reduce the temperature difference. After model validation, the effects of key operating parameters on the electrochemical performance and temperature distribution of the system are investigated. It is found that glycerol assistance can significantly reduce the operating voltage of the SOEC co-electrolysis system, thus saving over 55 % of electrical energy at 1073 K. Besides, increasing operating voltage, operating temperature and cathode H2O molar fraction promote the co-electrolysis process, leading to an increase in cathode H2O/CO2 conversion. Optimal values of the anode/cathode flow rates (Qan = 70–110 SCCM and Qca = 125–175 SCCM) and the anode glycerol molar fraction (Xan,GL = 0.05–0.15) are obtained to achieve both good electrochemical performance and uniform temperature distribution. Meanwhile, the proposed in-tube reformer can greatly reduce the temperature difference inside the cell, and by precisely controlling the structure and operating parameters of the system, a more uniform internal temperature distribution can be obtained, even allowing the system to be operated at homogeneous temperature conditions. This study provides a reference for the commercialization of efficient green syngas production and CO2 recycling by using renewable electricity.