Material-energy-emission nexus in the integrated iron and steel industry

Massive material and energy are consumed in the integrated iron and steel industry, which results in substantial emissions. Many technologies and policies have been employed in the industry to achieve sustainable steel-making. The potential of these technologies and policies is generally assessed at the facility/process level. The sitewide potential is usually overestimated or underestimated due to double-counting and missing items. To tackle this problem, a matrix model of the sitewide material-energy-emission nexus is developed in terms of the interconnection and interdependency of multiple flows. Based on the nexus model, the effects of operational actions on material, energy and emission intensities are investigated. In addition, the contribution of various operational parameters to the change in each flow is determined. Coke purchase, cast iron export, scrap steel utilization and metallic yield improvement are examined as a case study. The results showed that energy deficits or over-standard emissions may occur in certain cases influenced by the material-energy-emission nexus, and it is suggested to consider the whole-site energy balance and emission structure when making decisions. Finally, policy implications for reducing material consumption, energy consumption and emissions are provided.