Technoeconomic Evaluation of Ammonia Cracking for Hydrogen Production: A Question of Colors and Scale

Abstract The hydrogen economy has experienced rapid interest in recent years, emerging as a promising pathway to decarbonization. Despite its potential, hydrogen affordability is still a massive challenge particularly due to its requirement for renewable energy. For long distance hydrogen transport, ammonia is explored as a viable medium due to its matured and scaled existing infrastructure. This study delves into the role of ammonia as the hydrogen carrier, with a focus on evaluating the techno-economic viability and emission of ammonia cracking process. A comprehensive techno-economic analysis was conducted across two distinct ammonia cracking scales, between 4,000 tons/year and 400,000 tons/year of ammonia. The ammonia cracking process simulation model was built using the Symmetry-iCON software and includes main process units such as ammonia dehydrogenation, flue gas production and hydrogen purification. Assumptions were made on the efficiency of 99% of hydrogen production. We further employed a factorial method to estimate the capital expenditure (CAPEX) of the plant, a critical component in our analysis. Operation expenditure (OPEX) estimation was included by considering factors such as cost of raw material, electricity and manpower. The techno-economic analysis shows significant differences between two scales of operation. At the smaller scale of 4,000 tons/year, the minimum hydrogen selling price to achieve 20% IRR is 14.3 USD/kg H2, while at the larger scale of 400,000 tons/year, the price reduces to 3.7 USD/kg H2. Additionally, the analysis reveals OPEX, especially the cost of ammonia (grey, blue and green) is the primary cost driver in ammonia cracking process. A sensitivity study on ammonia costs reveals that fluctuations in OPEX have the most significant impact on hydrogen costs, compared to variability in CAPEX. Other operational costs considered within this work include installation of equipment, transportation and maintenance of the equipment. The fuel type and mix were studied to understand their impact on the overall system emission. The cases considered include the use of methane, a mix of methane and hydrogen and direct use of ammonia as fuel for the cracking system. This study provides valuable insights into the techno-economic aspects of using ammonia for hydrogen storage and transportation. While ammonia cracking is technically viable for hydrogen production, its economic feasibility depends significantly on the scale of operation and ammonia cost. From a technological perspective, alternative pathways that could lead to lower energy consumption could further lower the cost of ammonia cracking.