System evaluation of hydrogen power generation via green ammonia maritime transport considering levelized cost of delivered electricity (LCOD) and firm supply capability

As renewable energy deployment expands, integrating variable power sources into the grid and securing long-duration firm supply have become critical challenges, underscoring the need for hydrogen-based energy systems. However, the performance of hydrogen–ammonia value chains has not been adequately assessed at the system level, and an analytical framework for evaluating the delivered electricity cost based on the firm supply value is lacking. In this study, energy and exergy analyses were performed across the full eight-stage process chain of hydrogen power generation from overseas green ammonia—from renewable energy production through maritime transport to end-use power generation—to evaluate the system-level performance. An analytical framework integrating the cumulative energy-conversion efficiency and the levelized cost of delivered electricity (LCOD) was developed to quantitatively compare the systemic values of low-carbon power sources. The analysis, reflecting the 2025 technology levels, shows that the cumulative energy efficiency for the H 2 full-firing pathway is 28.1%, an improvement of 11.3 percentage points (pp) over that in the prior study. Loss analysis reveals that hydrogen-fired power generation (26%), ammonia synthesis (21%), and water electrolysis (15%) account for approximately 62% of the total energy loss. Tornado sensitivity analysis identified H 2 full-firing generation efficiency and electrolysis efficiency as the most influential parameters affecting the LCOD. At the global average solar-PV levelized cost of energy (LCOE) of 0.043 USD/kWh, the energy-cost-based LCOD lower bound is 0.153 USD/kWh, which, under the stated energy-cost-only assumptions, is potentially competitive with the domestic solar-PV firm supply cost (0.185 USD/kWh) and offshore wind supply cost (0.293 USD/kWh). When including the value-chain CAPEX/OPEX, the total LCOD ranged from 0.203 to 0.293 USD/kWh. Directional robustness was confirmed through partial-load scenarios, and even at a 23.1% cumulative efficiency (worst case), the LCOD competitiveness ranking was preserved. As a framework-level evaluation based on steady-state assumptions and excluding grid-avoidance costs, carbon costs, and life-cycle emissions, the reported LCOD constitutes a conservative lower bound. The findings suggest that the hydrogen–ammonia pathway may serve as a long-duration firm supply resource in the power system, subject to the lower-bound assumptions and exclusions stated herein.