Modeling and performance analysis of an integrated SOEC-Haber-Bosch system for offshore ammonia production

Offshore wind-powered ammonia provides a scalable solution for renewable energy storage, contributing to the transition toward a low-carbon economy. This study investigates offshore wind-powered ammonia production as a sustainable and scalable pathway for green ammonia. As part of this investigation, the authors developed a steady-state thermodynamic model in MATLAB® for an ammonia production plant featuring the design of an advanced GW-scale SOEC electrolyzer coupled with a Haber-Bosch synthesis loop and a cryogenic air separation unit. The primary findings can be summarized as follows: The green ammonia plant demands 1030 MW to produce 3037 tpd. The overall efficiency reaches 63% (LHV-NH 3 ), while the SOEC electrolyzer performs at the best case scenario with 86.5% (LHV-H 2 ). The Haber-Bosch synthesis loop provides 57% of total thermal power for feedwater evaporation. The partial load analysis reveals that the SOEC electrolyzer achieves 61% and 72% of minimum load for steam conversion scenarios of 70% and 85%, respectively. The stack temperature variations observed are mild and not greater than T stack = ±30 °C across the current density range examined. This fact allows for operation with reduced thermal stress. Finally, the study concludes that the SOEC electrolyzer performs better under a constant conversion strategy at partial load. Above nominal load, it performs slightly better under a constant flow strategy. These findings will encourage the development and adoption of large-scale SOEC electrolysis technology and green ammonia production. • Plant efficiency of 63% (LHV) with a specific consumption of 8.14 kWh/kg NH 3. • Advanced SOEC design with low-ASR stacks and current densities exceeding 1.5 A/cm 2 , achieving 87% (LHV) efficiency. • Minimum SOEC operating loads of 61% and 72% for SC ratios of 70% and 85%, respectively. • Stack temperature gradients remain within the safe limit of 5 K/cm.