(85f) Techno-Economic and Environmental Assessment of Onsite Green Hydrogen Production By Ammonia Cracking

In this study, the green hydrogen is produced from ammonia cracking in a multi catalytic packed bed reactor with an intermediate heating system by using Aspen Plus®. The process results were validated with experimental data for commercially available Ru/Al₂O₃ catalyst. The required thermal energy for the cracking is generated from the combustion of about 9% of feed ammonia. In the ammonia combustion, furnace thermal efficiency, fuel-saving, and product yield are analyzed, and optimum values are found to be 59%, 22% and 77%, respectively. The overall thermal efficiency of the developed process is calculated to be 79%. To monitor the NO_x emissions, the parameters such as equivalence ratio, combustion temperature and pressure are analyzed to witness the optimum operating conditions. The blending of hydrogen with fuel ammonia resulted in higher NO_x emissions, which are reduced by recirculation of 30% of the flue gas with air-fuel stream. Two bed TSA and four bed PSA processes are developed in Aspen Adsorption, recovery of 80% and purity of 99.999% are obtained. Economic analysis is performed, including an itemized cost estimation, sensitivity analysis of process and economic parameters, uncertainty analysis and profitability analysis. The process parameters such as furnace temperature, flue gas recirculation, ammonia decomposition temperature, market ammonia supply pressure, ammonia decomposition pressure, hydrogen purification pressure and equivalence ratio, and economic parameters of CAPEX and OPEX are considered. Cost of hydrogen production is found to be highly sensitive on the price of ammonia. Whereas the LCOH is estimated and found to be 6.05 USD/kg of H₂. Monte-Carlo simulation method is applied to present LCOH keeping in mind uncertainties in prices of equipment, energy, and raw material. The profitability analysis is conducted by calculating profitability indicators like ROI, PBP, NPV, IRR and PVR for 25-year plant life with 10% discounted rate. In addition, this study reports global warming potential analysis under different energy source scenarios.