Thermodynamic analysis of a solid oxide electrolysis cell system in thermoneutral mode integrated with industrial waste heat for hydrogen production

Abstract

In this study, a widely applicable hydrogen production system based on solid oxide electrolysis cells (SOEC) is proposed for industrial waste heat recovery. When the thermoneutral mode is employed to maintain the isothermal state of SOEC, the performances of a single SOEC and the system are comprehensively analyzed respectively. The results show that an increase in SOEC temperature leads to a rise in current density, power, hydrogen production, and inlet steam flow rate. Conversely, as the steam conversion rate rises, these parameter values decrease. A set of 3D performance maps are provided to illustrate parameter variations. The thermoneutral data of SOEC can be utilized in various systems, not limited to the proposed one.Increasing the steam conversion rate improves energy efficiency and energy consumption performance of the system, but decreases the inlet steam flow rate and production capacity. A temperature rise improves the inlet steam flow rate and production capacity but has a slight effect on energy efficiency and energy consumption performance. When the inlet steam flow rate is 50 kg/h and the temperature is 800 °C, the system achieves a maximum hydrogen production of 2.473 kmol/h. The proportion of waste heat supply to total energy consumption fluctuates between 15.5 % and 20.6 % across the operation conditions. It shows great potential for hydrogen production utilizing industrial waste heat. Meanwhile, the stack consumes almost all of the electrical energy.