Validation challenges in solid oxide electrolysis cell modeling fueled by low Steam/CO2 ratio

This study addresses some of the challenges in the modeling of solid oxide electrolysis cells (SOECs), particularly for feed gases containing low inlet steam-to-CO2 concentration ratios. The common approach used for SOEC modeling is to neglect the CO2 electrochemical reduction reaction. A comprehensive model validation versus experimental results presented by the Idaho National Laboratory (INL) is performed in this paper. Our validation results under various operating conditions show that the model deviation with experimental data increases above certain current densities, e.g., 1200 Am-2. It can also be seen that the electrochemical reaction involving CO2 can only be neglected when the steam flow supplied to the cell is high enough to support the water-gas shift reaction. Suppose the concentration of inlet water supply is not enough to support the reverse water gas shift reaction. In that case, the electrochemical reduction of CO2 has to be considered to avoid model-predictive results that are far from available experimental observations. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study addresses the challenges in modeling solid oxide electrolysis cells (SOECs) with feed gases containing low steam-to-CO2 concentration ratios. The common approach of neglecting the CO2 electrochemical reduction reaction in SOEC modeling is validated against experimental results. The validation results show that the model deviation with experimental data increases at certain current densities. It is also shown that when the steam flow supplied to the cell is high enough to support the water-gas shift reaction, the electrochemical reaction involving CO2 can be neglected.