Techno-Economic Assessment of Industrial Symbiosis Between Steel and Urea Plants: The INITIATE Process

The steelmaking and fertilizer industries accounted for approximately 10% of global anthropogenic CO₂ emissions in 2024. This study examines an industrial symbiosis concept, termed INITIATE, which integrates these two sectors to enhance resource efficiency and to reduce CO₂ emissions. The proposed system utilizes process gases from steel production as a feedstock for urea synthesis, using the sorption enhanced water gas shift (SEWGS) technology for simultaneous CO₂ capture and production of a H₂-N₂ mixture. This stream is suitable for ammonia synthesis, which subsequently reacts with part of captured CO₂ in a downstream urea production process. Two sizes of fertilizer production are analyzed: a small-scale configuration producing 224 t_urea/day and a large-scale case with a production capacity of 1500 t_urea/day. Simulation results indicate that the integrated symbiotic configuration of the INITIATE system enables substantial reductions in both the natural gas consumption and direct CO₂ emissions. Under scenarios utilizing renewable electricity, the level of CO₂ avoidance can reach up to 68%. The specific primary energy consumption per unit of CO₂ avoided (SPECCA) ranges from -2.5 to 2.5 GJ/t_CO₂ . Negative values reflect a net reduction in primary energy demand, resulting from process integration and efficient resource utilization. From an economic perspective, the cost of CO₂ avoidance is estimated at 24 €/t_CO₂ for the small-scale plant, increasing to 130 €/t_CO₂ for the large-scale configuration. Sensitivity analyses reveal that these costs are highly dependent on the prices of electricity and natural gas, with lower electricity prices and higher natural gas prices improving the economic performance of the INITIATE system compared with the base and reference cases.