Life cycle assessment of gas-based EAF steel production: environmental impacts and strategies for footprint reduction

PurposeDespite its sizeable role in the global economy, the steel industry is also one of the world's largest energy consumers and a significant source of greenhouse gas emissions. Iran is one of the world's top ten steel producers, with over 77% of its steel produced in electric arc furnaces (EAF). As a result, a thorough impact assessment is essential to understand the possible negative environmental impacts. The purpose of this study is to perform a life cycle assessment (LCA) on gas-based direct-reduction-iron-EAF steel production in Iran.MethodsThe environmental impacts of steel production were evaluated in this study. The most influential processes and inputs were determined by analyzing their contributions separately. Due to the fact that the inputs of the EAF process can vary based on the context and availability of resources, multiple scenarios were defined, and the results were compared. SimaPro and OpenLCA software, the Ecoinvent database, and the IMPACT2002+evaluation method were used in this study. The data for the life cycle inventory was derived from the average performance of factories over a one-year period, with 1 ton of hot-rolled steel serving as the functional unit.ResultsThe findings indicated that among the various categories, non-renewable energy, global warming, and respiratory inorganics have the greatest impact, accounting for 86.4% of the total. The most significant environmental impacts of processes are associated with the EAF (35%), direct reduction iron (DRI), and oxide pellet processes (28.9% and 17.1%, respectively), while the most significant environmental impacts of inputs are associated with electricity (33.8%) and gas consumption (25.8%). Sensitivity analysis was also performed to assess the significance of the inputs. Given that the EAF process's primary inputs are scrap iron, two scenarios involving coal-based and gas-based sponge iron were defined, and the impact of each scenario was evaluated.ConclusionSuggestions for sustainable production were made based on the assessment of the results. The low price of natural gas and abundance of iron ore in Iran make the production of gas-based steel with sponge iron more appealing. Additionally, it was shown that using sponge iron in the coal-based process results in high environmental impacts compared to other scenarios (gas-based systems) which can have a significant impact on global warming. This is particularly important because coal-based processes are widely used in India and China due to abundant coal resources.