Flexible calcium looping for CO2 capture in electric Arc Furnace steelmaking: A techno-economic analysis

This study presents a techno-economic analysis of four configurations of the Calcium Looping (CaL) technology, tailored to enhance system flexibility for capturing CO₂ from the fluctuating flue gases generated by a scrap-based Electric Arc Furnace with a capacity of 112 t_steel/h. The configurations differ based on the solids circulation strategy between reactors (constant or variable) and the presence of one or two intermediate solids storage vessels. Configurations incorporating intermediate solids storage demonstrated operational advantages, including enhanced process stability and downsized calciner island components. Moreover, the plant configuration with two intermediate solids storages led to the lowest specific fuel consumption of 5.85 MJ per kg_CO2 captured.

Under the assumptions considered, the CaL system achieved a CO₂ capture rate of 91 % from the EAF off-gas. Moreover, using residual forestry biomass as fuel in the calciner enabled to achieve negative emissions with net CO₂ removal rates of 13-26 t_CO2/h, corresponding to 100-200 kg_CO2 removed per t_steel produced.

From an economic standpoint, increment in steel cost ranged from 26 to 36 €/t_steel (assuming a carbon tax of 100 €/t_CO2), with costs of CO₂ avoided of 202-255 €/t_CO2.