Hydrogen Production Intensification by Energy Demand Management in High-Temperature Electrolysis

Solid oxide electrolysers (SOEs) can decarbonise H2 supply when powered by renewable electricity but remain constrained by high electrical demand and integration penalties. Our objective is to minimise the electrical (Pel), and thermal (Qth) energy demand per mole of H2 by jointly tuning cell temperature, steam fraction, steam utilisation, pressure, and current density. Compared with prior single-variable or thermo-neutral-constrained studies, we develop and validate a steady-state, process-level optimisation framework that couples an Aspen Plus SOE model with electrochemical post-processing and heat caused by ohmic resistance recovery. A Box–Behnken design explores five key operating parameters to capture synergies and trade-offs between Qth and Pel energy inputs. Single-objective optimisation yields Pel = 170.1 kJ mol⁻¹ H2, a 41.4% reduction versus literature baselines. Multi-objective optimisation, using an equal-weighted composite desirability function aggregating thermal and electrical demands, further reduces Pel by 21.2% while balancing thermal input, 4–8% lower than single-objective baselines at moderate temperature (∼781°C) and pressure (∼17.5 bar). Findings demonstrate a clear process intensification advantage over previous studies by simultaneously leveraging operating parameter synergies and heat-integration. However, results are bounded by steady-state, perfectly mixed, isothermal assumptions. The identified operating windows are mechanistically grounded targets that warrant stack-scale and plant-level validation.