Thermodynamic and economic assessment of a solar-assisted ORC-hydrogen system for natural gas pressure energy recovery

Abstract

A significant amount of pressure energy is wasted during natural gas pressure reduction, while the cold energy generated from expansion is utilized inefficiently and typically relies on fossil fuel combustion for reheating. To address these challenges, this study proposes a pressure energy recovery system designated Int-ORC that combines an Organic Rankine Cycle, photovoltaic power generation, and alkaline water electrolysis for hydrogen production. Based on actual operational data from a pressure reduction station in Inner Mongolia, China, a coupled thermodynamic and economic model was developed using MATLAB to evaluate system performance. The Int-ORC system is compared against a basic pressure energy recovery system designated Ref. A and a pressure energy recovery system with hydrogen production designated Ref. B. The results show that the Int-ORC system achieves primary energy saving rates of 3.81 in summer and 2.98 in winter, representing improvements of 0.14 and 0.81 over Ref. A and Ref. B, respectively. The cold energy is fully utilized, achieving zero fossil fuel consumption. Hydrogen production rates reach 18.41 m³/h in summer and 18.78 m³/h in winter, both outperforming Ref. B. This study provides a technical foundation for the construction of next-generation gas stations integrating power generation, hydrogen production, and hydrogen blending functionalities.