Urea, a key derivative of ammonia, is widely used in agriculture and has a significant impact on food security. This study evaluates a sustainable urea production pathway that utilizes hydrogen generated from water electrolysis for green ammonia synthesis and CO2 captu
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Urea, a key derivative of ammonia, is widely used in agriculture and has a significant impact on food security. This study evaluates a sustainable urea production pathway that utilizes hydrogen generated from water electrolysis for green ammonia synthesis and CO2 captured from a cement plant using an MEA-based process. This study employed Aspen Plus V12.1 and MATLAB to develop rigorous system-level models of all subsystems involved in the sustainable urea production process. These subsystems include a cryogenic air separation unit (CASU), a modular system of alkaline electrolysers (AEL), a green Haber-Bosch (HB) process, an MEA-based CO2 capture system, and the Stamicarbon process. To enhance the energy efficiency and cost-effectiveness of urea production, waste heat generated during green ammonia synthesis in the HB process was integrated into the stripper column of the MEA-based CO2 capture system for solvent regeneration. A detailed economic analysis was conducted to assess the impact of this heat integration (HI) on reducing the CO2 capture costs and, consequently, the overall urea production costs. Additionally, several heat supply scenarios were evaluated to meet the heat demand of the CO2 stripper column in the Stamicarbon process. These included natural gas combustion, a cascade heat pump (HP), and natural gas combustion integrated with a cryogenic CO2 capture (CCC) system. The results indicated that HI significantly decreases both the energy penalty and costs of the MEA-based CO2 capture process, reducing the CO2 capture costs by 41.27 % in 2024 and lowering the energy penalty by 50.40 %. Among the scenarios investigated, the cascade HP with HI proved to be the most cost-effective option for urea production. Additionally, electricity costs for operating the modular alkaline electrolyzers (AEL) dominate the sustainable urea production expenses, with 88.07 %–91.26 % of electricity costs allocated to AEL, depending on the selected production scenario. The modular AEL also represents the largest share of initial investment costs, accounting for 90.62 % of total capital expenditures in the urea production process.