Optimal Scheduling of Coal Mine Integrated Energy Systems Considering Stepped Carbon-Green Certificate Mutual Recognition and Gravity Energy Storage

To address the issues of low renewable energy accommodation rates, high carbon emissions, and poor operational economy in mining areas of Northwest China, this paper proposes an optimal scheduling model for coal mine integrated energy system (CMIES) that incorporates the mutual recognition of stepped carbon and green certificates, as well as gravity energy storage. Initially, the basic CMIES model was developed by considering the diverse utilization of mine resources, including coalbed methane and gravity energy storage of abandoned mines. Subsequently, to enhance the economic efficiency and energy utilization rate of the CMIES, coupling equipment such as carbon capture, power-to-gas, and combined cooling, heating, and power units was incorporated into the system. Additionally, a flexible load model for electricity, heat, and cooling was established to improve the system's operational flexibility. Furthermore, a mutual recognition mechanism for stepped carbon and green certificates was introduced to encourage the utilization of renewable energy equipment through market interactions. Finally, a mixed-integer programming model was formulated to minimize the total operating cost of the system and was solved using Cplex. The simulation results demonstrate that the proposed model significantly enhances the renewable energy accommodation rate in mining areas while reducing system carbon emissions, striking a balance with operational economics, thereby providing a theoretical foundation for the low-carbon and economically viable transition of CMIES.