Thermodynamic analysis of a new polygeneration system integrated with solar-assisted biomass gasification and chemical looping nitrogen substitution

Biomass gasification is widely applied in chemical and power industries owing to its environmental benefits, high thermal efficiency, and waste-to-resource potential. Conventional technologies, however, typically employ air or oxygen (O2) from air separation unit (ASU) or electrolyzers, resulting in high energy consumption and low efficiency. To address this, a new polygeneration system integrating chemical looping nitrogen substitution (CLNS) with solar-assisted biomass gasification is proposed. In CLNS, CO2 acts as an oxygen partial pressure regulator to replace nitrogen in air, producing an O2–CO2 mixture that serves as the gasifying agent. Thermodynamic performance is evaluated under design conditions, with emphasis on the effects of the CO2 to biomass mass flow ratio and CLNS temperature. Results show energy efficiency, effective carbon conversion efficiency (ECCE), and exergy efficiency of 73.46%, 96.90%, and 70.83%, respectively. Compared with a conventional system integrating ASU and biomass gasification, these values represent improvements of 14.11%, 24.04%, and 12.82%. Furthermore, the minimum specific energy demand for O2 production is 0.08 kWh/kg at a CLNS oxidation temperature of 870 °C and reduction temperature of 860 °C. Overall, the proposed system provides an efficient pathway for biomass gasification.