Multiphysics modeling of solid oxide steam electrolysis with varying support structures for green hydrogen production

• A multiphysics ECT model was developed for ASC, CSC, and ESC SOEC. • ASC exhibited highest exergetic efficiency (∼43 %) but strongest radiation losses. • Ohmic losses drop by ∼ 0.1 V in anode-supported vs. electrolyte-supported cells. • Anode-supported cells with high porosity show lowest overall overpotentials. • Steam fraction increase from 20–80 % lowers voltage by up to 80 mV at high current. Hydrogen is broadly recognized as a vital enabler of clean and sustainable energy systems. Among the available production technologies, solid oxide electrolysis cells (SOEC) offer superior efficiency for high temperature steam electrolysis. This study develops a comprehensive electrochemical-thermal (ECT) model of SOEC to evaluate the coupled effects of operational parameters (temperature, pressure, steam molar fraction) and structural characteristics (support type, porosity, and pore diameter) on electro-thermal performance and efficiency. The model is validated against experimental data for various types of supports, showing strong agreement across experimental conditions. Key findings reveal that increasing temperature reduces total potential by ∼ 150 mV and ohmic losses by over 20 %, while increasing steam molar fraction from 20 % to 80 % decreases total potential by ∼ 80 mV due to improved reactant availability. Optimizing microstructural parameters, such as increasing pore diameter from 1 µm to 4 µm reduces concentration overpotential by ∼ 35 mV. Thermal analysis shows a rise in heat input from 1244 W to 7460 W with increasing current density (1000–6000 A/m 2 ), and support-specific differences in convective and radiative heat losses. Exergy analysis reveals that anode-supported configurations offer the highest exergetic efficiency (∼43 %), significantly outperforming electrolyte-supported cells (∼37 %). These results highlight pathways for thermally optimized, structurally efficient SOEC. Future work should address degradation, transient, and thermal recovery to enhance durability.