Advanced Thermal Integration of Haber–Bosch Waste Heat for Competitive Hydrogen Production Using SOE and Hybrid AWE–SOE Systems

This study investigates the integration of Haber–Bosch waste-heat recovery with solid oxide electrolysis (SOE) and evaluates its techno-economic implications through the comparison of stand-alone SOE, hybrid SOE–AWE, and stand-alone AWE hydrogen production configurations. The HB synthesis loop was first simulated and analyzed to quantify the residual heat available after internal heat recovery and assess its thermal suitability for SOE steam generation. The recoverable HB heat initially covers 55% of the SOE evaporator duty. Further optimization of the SOE-side heat-exchanger network using Aspen Energy Analyzer V14 increases this coverage to 63%, enabling SOE to thermally support up to 63% of the hydrogen demand. Additional heat integration opportunities identified using Aspen Energy Analyzer (AEA) increase this coverage to 63%, enabling the SOE system to supply up to 63% of the hydrogen demand. The remaining hydrogen production requirement is investigated under two distinct configurations: (i) a stand-alone SOE system with an internal steam generation unit and (ii) a hybrid configuration consisting of 63% SOE and 37% AWE. These SOE-based configurations are evaluated and compared with a conventional alkaline water electrolysis (AWE) system. The energy analysis demonstrates that SOE-based systems significantly reduce overall energy consumption due to their higher electrochemical efficiency and effective utilization of industrial waste heat. The economic assessment yields LCOH values of 3.90, 3.44, and 2.79 $/kg H2 for the stand-alone SOE, hybrid SOE–AWE, and stand-alone AWE configurations, respectively. Sensitivity analysis indicates that reductions in SOE stack cost combined with improvements in stack lifetime can enable the hybrid configuration to achieve an LCOH of 2.79 $/kg H2, reaching cost parity with the baseline AWE configuration and demonstrating its potential as an energy-efficient and economically competitive pathway for green ammonia production.