Robust low-carbon planning of regional integrated energy systems with cross-seasonal hydrogen shifting and biogenic carbon recycling

This study proposes a cross-seasonal carbon-hydrogen coupled integrated energy system to improve long-duration flexibility and low-carbon operation under high renewable penetration and multi-energy uncertainty. A two-stage robust optimization framework is developed to jointly determine capacity planning and recourse dispatch. The key novelty is that hydrogen energy storage is modeled as an inter-period energy carrier across concatenated seasonal representative days, extending its role from conventional intra-day balancing to cross-seasonal energy shifting. Meanwhile, a biogenic carbon recycling pathway is established based on CO 2 separated from the biogas upgrading process, enabling coordinated utilization of green hydrogen for low-carbon synthetic gas supply. The resulting planning problem is solved using a column-and-constraint generation algorithm. The results show that hydrogen energy storage becomes the main robustness resource in the proposed framework. In winter, the cross-seasonally shifted hydrogen supports 8.01% of seasonal demand, indicating its practical value in alleviating structural supply–demand mismatch. Compared with the intra-day balancing case, the proposed model reduces carbon intensity by 48.1%, while achieving a biogenic CO 2 utilization rate of 69.56% and a gas self-sufficiency ratio of 73.82%. Sensitivity analysis further suggests that a moderate uncertainty budget can better balance economic efficiency and operational security, offering useful insight for robust low-carbon planning of integrated energy systems.