Low-carbon optimization of hydrogen-integrated energy systems with coordinated P2G–CCS and integrated demand response

The escalating severity of global carbon emissions has intensified the demand for low-carbon operation of integrated energy systems (IES). Hydrogen-integrated energy systems (hydrogen-IES), enabled by multi-energy coupling and cross-sector flexibility, represent a promising pathway for deep decarbonization in industrial energy systems. This paper proposes a low-carbon optimization framework for hydrogen-IES by coordinating power-to-gas (P2G) and carbon capture and storage (CCS) technologies with integrated demand response (IDR). To enhance renewable energy utilization and reduce carbon intensity, a multi-hydrogen supply strategy is developed in which green hydrogen partially replaces conventional gray hydrogen, while carbon recycling is achieved through coordinated P2G–CCS operation. Meanwhile, a staged integrated demand response mechanism is introduced to jointly coordinate electricity, heating, and cooling loads by combining price-based demand response with incentive-based programs, thereby improving system flexibility under high renewable penetration. A coastal industrial park is employed as a case study to evaluate the economic and environmental performance of the proposed framework. The model is calibrated using representative industrial-park load profiles, equipment parameters, and market coefficients, and is validated through energy-balance checks, component-limit checks, scenario consistency analysis, and parameter sensitivity analysis. Simulation results demonstrate that, under a realistic multi-hydrogen-supply configuration with coordinated P2G–CCS operation and integrated demand response, the proposed approach reduces carbon emissions by more than 50% and total system cost by approximately 24%, while significantly improving renewable energy accommodation. These findings highlight that the synergistic coordination of P2G–CCS and staged demand response enables a structurally efficient pathway to jointly optimize carbon mitigation, economic performance, and renewable energy integration in hydrogen-IES.