Chemical and electrochemical pathways to low-carbon iron and steel

Currently, the iron and steel industry is responsible for 7% of global CO2 emissions. This review summarizes the operational principles of current emissions-intensive steelmaking technologies and examines emerging low- and zero-carbon technologies aimed at significantly reducing emissions. Key current technologies discussed include blast furnaces, electric arc furnaces, and smelting processes. Promising low-carbon alternatives feature techniques such as hydrogen direct reduction, hydrogen plasma-smelting, and ammonia-based reduction, as well as electrolytic iron production methods. Each approach's advantages are highlighted, while also identifying existing research challenges. The industry produces approximately 1.85 billion tons of steel annually, generating about 1.8–2.0 tons of CO2 per ton of steel. Without the adoption of new low-carbon practices, emissions from the iron and steel sector, which currently accounts for around 24% of industrial CO2 emissions, are projected to rise as production increases. Establishing alternative processes to blast furnaces, particularly those that do not rely on fossil fuels, is crucial for meeting emissions reduction targets and mitigating climate change impacts. This review provides insights into the current landscape of steel production and emphasizes the need for scalable low-carbon solutions.