Thermodynamic and environmental impact analysis of a novel solar SOFC-based zero-carbon emission CCHP system coupled with a water gas shift membrane reactor for CO2 separation

To efficiently utilize solar energy and reduce energy consumption for CO₂ separation, a solar-assisted solid oxide fuel cell-based combined cooling, heating, and power system integrated with a partially covered parabolic trough photovoltaic thermal collector, a water gas shift membrane reactor, and a supercritical CO₂ cycle is proposed. The water gas shift membrane reactor replaces the conventional fuel cell afterburner, controlling exhaust gas composition to enrich CO₂ with nearly zero energy input. Thermodynamic and environmental performances of the solar-assisted system are compared with the system without solar assistance, the oxy-fueled system, and the traditional air-mixed combustion system. The results illustrate that the solar-assisted system achieves energy efficiencies of 87.54 % in summer and 95.68 % in winter, exceeding the traditional system by 6.81 and 8.00 percentage points, respectively. The exergy efficiencies reach 57.37 % and 58.48 %, and the largest exergy losses occur in the partially covered parabolic trough collector, accounting for 27.4 % of the total, followed by the fuel cell at 14.8 %. The CO₂ emission factors based on electricity, energy, and exergy are lowest for the solar-assisted system in both summer and winter. The system's power output and exergy efficiency increase with fuel cell operating temperature, while total energy output and energy efficiency decrease. Increased solar irradiation further improves electricity and total energy output. These findings indicate that coupling solar energy with a water-gas shift membrane reactor in fuel cell systems markedly improves efficiency and reduces emissions, providing a promising pathway toward low-carbon, high-efficiency energy conversion.