Coupling renewable energy and storage technologies with hydrogen-based steel production: A design and scheduling optimization approach

The decarbonization of energy-intensive industries is essential to achieve global greenhouse gas emission reduction targets. Steel production, responsible for approximately 7% of global CO 2 emissions, requires innovative low-carbon alternatives. One promising option is the use of renewable electricity and green hydrogen in the Direct Reduced Iron (DRI) process. In this study, an integrated energy system to supply renewable electricity and hydrogen to a DRI-based steel plant is analyzed. The proposed network combines two renewable power generation technologies (solar photovoltaic and onshore wind) with three complementary storage solutions (batteries, compressed hydrogen, and Liquid Organic Hydrogen Carriers (LOHCs)). A mathematical optimization framework is developed to determine both the optimal sizing and operational strategy of the system. The methodology is applied to the provinces of mainland Spain as a case study. Results highlight the critical role of integrating multiple generation and storage technologies to ensure a continuous supply of electricity and hydrogen. They also reveal a strong dependence on geographical location for design and technology selection, driven by variations in renewable resource availability. The energy cost per ton of steel is estimated at 500–600 €/t. It exceeds five fold current costs but is expected to decline significantly with future technology improvements. Hence, these integrated renewable systems are regarded to be a technically feasible and economically competitive option in the future. Overall, it represents a key enabler for the deep decarbonization of the steel sector.