Research on Innovative Shale Gas Exploitation and Utilization System Based on CO2 Integrated with Displacement, Power Generation and Refrigeration

This paper presents a novel, integrated supercritical CO₂ system for shale gas development, comprising a supercritical CO₂ shale gas extraction system, a gas turbine system, a supercritical CO₂ power generation system, and a transcritical CO₂ refrigeration system. A comprehensive thermodynamic and economic analysis is conducted for this integrated energy development system. To enhance system performance across multiple dimensions, three objective functions are proposed for optimization: exergy efficiency, levelized energy cost (LEC), and heat transfer area per unit power output (APR). First, the effects of key operating parameters-including the gas turbine pressure ratio, gas turbine inlet temperature, supercritical CO₂ pressure ratio, the temperature difference between flue gas and the supercritical CO₂ top cycle, and the temperature difference between flue gas and the supercritical CO₂ bottom cycle-on system performance were analyzed through parametric studies. Next, the optimal system parameters were determined using a multi-objective optimization method based on a genetic algorithm. The optimization results reveal that, when exergy efficiency and LEC are used as dual-objective functions, the system achieves an optimal exergy efficiency of 60.5% and an LEC of 6.3 cents/(kW·h). Furthermore, when exergy efficiency, APR, and LEC are considered as objective functions, the system attains an optimal exergy efficiency of 59.5%, an APR of 0.21 m²/kW, and an LEC of 6.3 cents/(kW·h). The compound shale gas development system proposed in this paper demonstrates excellent economic viability, environmental sustainability and operational efficiency. The research outcomes offer an innovative solution for the development of shale gas and contribute to the advancement of research on new energy systems.