Performance comparison of solid oxide steam electrolysis cells with/without the addition of methane

Abstract

Hydrogen is considered a clean energy carrier for the future. At present, the production of hydrogen via a solid oxide electrolysis cell is of interest because water is the only reactant used; however, hydrogen production through electrolysis technology is still costly due to high electrical energy consumption. To reduce this energy demand, an addition of methane to the anode side of the solid oxide electrolysis cell, where it behaves like the anode side of the solid oxide fuel cell and generates heat and electricity to accomplish the electrolysis process, is one interesting method. In this study, modeling of the solid oxide fuel-assisted electrolysis cell is performed based on an electrochemical model to analyze the performance of the electrolyzer with/without the addition of methane in terms of the power input and the energy efficiency. In addition, the effect on the electrolyzer cell by key operating parameters, such as current density, steam fraction, steam-to-carbon ratio, temperature, pressure, steam utilization and fuel utilization, is presented. The simulation analysis shows that the performance of the solid oxide fuel-assisted electrolysis cell is higher than that of conventional solid oxide electrolysis cell, as it requires a lower power input. Furthermore, it is possible to run the solid oxide fuel-assisted electrolysis cell without an external electrical energy input.