Development and evaluation of FINEX off-gas capture and utilization processes for sustainable steelmaking industry

•Current CO2 emissions of FINEX by burning the off-gases is 2.78 ton/ton-Slab.•CO2 reduction potential through FINEX off-gas capture and utilization is estimated.•Post-combustion capture gives 35% lower CO2 emissions than the current practice.•Pre-combustion capture gives the lowest CO2 avoidance cost of 68 USD/ton-Slab.•Methanol production is a viable option under green electricity and high methanol price. FINEX process was proposed as an environmentally friendly option for steelmaking. To further its environmental friendliness, this study proposes and evaluates three options for FINEX off-gas (FOG) capture and utilization: post-combustion CO2 capture (Case 1), pre-combustion CO2 capture (Case 2), and methanol production following the pre-combustion CO2 capture (Case 3). These options are designed through simulation and are comparatively evaluated in terms of their net CO2 emissions and economics by conducting CO2 lifecycle assessment (LCA) and techno-economic analysis (TEA). In the latter, CO2 avoidance cost is estimated to assess the economic feasibility of each option. Case 1 was observed to give the largest amount of CO2 emission reduction, which is 35% lower than the current FOG utilization method of burning it for electricity generation. Case 2 showed the lowest CO2 avoidance cost of 68 USD/ton. Although Case 3 was estimated to give higher net CO2 emissions than Case 1 and higher CO2 avoidance cost than Case 2, sensitivity analysis revealed that the outcome depends strong on the global warming impact of the mixed electricity, carbon credit price, and methanol price and it can become an attractive option in the future.