Effective blue ammonia production: A focus on carbon capture and nitrogen supply methods

As the demand for ammonia continues to grow, environmentally sustainable production methods have become essential. Blue ammonia, which integrates carbon capture into conventional gray ammonia production, presents a viable alternative. However, the selection of carbon capture and nitrogen supply methods significantly influences the overall performance, necessitating systematic evaluation. This study addresses this gap by analyzing and comparing various blue ammonia production configurations based on energy, techno-economic, and environmental impact. Three configurations were designed and assessed, incorporating two carbon capture technologies and three nitrogen supply methods: (1) oxy-fuel combustion with an air separation unit (Case A), (2) monoethanolamine-based carbon capture with external nitrogen purchase (Case B), and (3) monoethanolamine-based carbon capture with nitrogen pressure swing adsorption (Case C). The results indicate that Case B achieved the lowest specific energy consumption (SEC) of 5.30 MJ/kg NH₃, while Case A exhibited the highest SEC of 6.07 MJ/kg NH₃. In the techno-economic analysis, Case C proved to be the most cost-effective, with a levelized cost of ammonia of $495.35/t NH₃, representing cost reductions of 8.31 % and 5.95 % compared to Cases A and B, respectively. From an environmental perspective, Case B demonstrated the lowest carbon emissions at 0.647 t CO₂/t NH₃, whereas Case C had the highest at 0.666 t CO₂/t NH₃. This study is the first to comprehensively evaluate the combined effects of carbon capture and nitrogen supply methods on blue ammonia production. The findings provide a comparative assessment of blue ammonia production pathways and offer valuable insights for optimizing sustainable ammonia production.