Advancing conventional power systems: Life cycle assessment of ammonia-based decarbonization

The transition to clean energy systems has prompted discussion on ammonia co-combustion in conventional power plants. However, because ammonia is both energy- and carbon-intensive to produce, its potential for global CO₂ reduction requires comprehensive assessment. This study integrates process simulation and life cycle assessment (LCA) to evaluate ammonia co-combustion in a 1000 MWe large-scale power plant. Five ammonia production pathways (gray, blue, wind, solar, nuclear), three coal types (bituminous, sub-bituminous, lignite), and co-combustion ratios ranging from 0 to 50 % were analyzed. Among all scenarios, co-combusting nuclear-based ammonia with lignite yielded the greatest global warming potential (GWP) reduction up to 1,258,919 tons CO₂ per year. Furthermore, under future technology application scenarios, including low-carbon ammonia production and carbon capture and storage (CCS) integration, the CO₂ intensity decreased from 762 to 246 g CO₂/kWh. In contrast, scenarios using blue ammonia produced with fossil fuel-based electricity grids resulted in noticeably higher NO_x emissions, underscoring the influence of upstream energy sources. These results highlight the critical role of ammonia production methods and national electricity mixes in determining overall environmental performance. The findings of this study can inform fuel import policies, low-carbon technology selection, and transitional energy strategies, particularly for countries aiming to reduce emissions from coal-fired power plants while utilizing existing infrastructure.