Performance Analysis of Solid-Oxide Electrolysis Cells for Syngas Production by H2O/CO2 Co-Electrolysis

Abstract

High-temperature solid oxide electrolysis cells (SOECs) are promising technologies to store excess renewable energy generation. In this work, the mathematical model of SOEC, which can describe the behaviour of a cathode-supported SOEC operating for H₂O and CO₂ co-electrolysis, is developed from mass balance, dusty gas model, and electrochemical model. The validated SOEC model is used to analyse the influence of the reversible water-gas shift reaction taking place on the cathode on the performance of the SOEC for syngas production. The simulation results show that the reverse water-gas shift reaction is highly pronounced at the cathode surface due to high CO₂ component and can contribute to CO production. The rate of water-gas shift reaction increases along the depth of the cathode to the three-phase boundary. At the three-phase boundary, an increase in operating temperatures results in the enhancement of the rate of water-gas shift reaction. Additionally, regarding the SOEC performance, the electrical energy consumed for co-electrolysis in SOEC decreases with increasing temperature because the activation overpotentials and ohmic overpotentials are lower.