Multi-objective and multi-stage capacity planning for low-carbon iron and steel industry empowered by wind-gas‑hydrogen energy

The decarbonization transition of the iron and steel industry (ISI) necessitates an overshooting of its energy mix from a predominantly coal-consuming to a predominantly renewable energy-consuming one, including wind and hydrogen. This also presents novel challenges to the energy economy, efficiency, and flexibility of low-carbon ISI. To overcome this challenge, this paper proposes a multi-objective and multi-stage planning (MSP) model for ISI coupled with multi-energy forms. The MSP strategy, which considers the stage-adjustable hydrogen proportion (H₂-CO ratio) used in iron production, is proposed as a means of fully considering energy development at different stages to make optimal equipment configuration. Moreover, a multi-objective capacity planning model is developed to establish energy economic, efficiency and flexibility objectives based on the actual energy policies implemented in China. Finally, an enhanced AUGMECON-R algorithm (EARA) is devised to address the bilinear constraints inherent to the model, thereby facilitating an efficient solution process. The simulation results substantiate the efficacy of the MSP strategy, illustrate the substantial value of the stage-plannable H₂-CO ratio for ISI's economy and flexibility enhancement, and demonstrate that EARA can markedly enhance solution efficiency while maintaining an acceptable level of accuracy.