High-efficient and carbon-free biomass power generation hybrid system consisting of chemical looping air separation and semi-closed supercritical CO2 cycle with a bottoming organic Rankine cycle

Abstract

Herein, a novel biomass power generation system, comprising of CO2-assisted gasification unit, chemical looping air separation (CLAS) unit, semi-closed supercritical CO2 (sCO2) cycle with the bottoming ORC unit, was proposed to overcome the problems of low-efficiency and high-pollution rendered by traditional biomass utilization method. And the heat integration between those subunits was well designed based on the principle of energy cascade utilization. The sensitive analysis was carried out to clarify the reasons behind thermodynamic performance variation, and the optimized net power efficiency reached 38.76% when the CO2/C ratio was 0.25, gasification temperature was 830 °C, sCO2 turbine inlet temperature and pressure were 1200 °C and 300 bar respectively, which was superior to 28.01% of biomass integrated gasification combined cycle system. In addition, the exergy analysis found that modification efforts should be exerted on CLAS and sCO2 compression pump, whose exergy destruction were 7.58 MW and 5.15 MW, respectively. Besides, its environmental and economic merits were obvious with the CO2 specific emission at 0.31 kg/MWh, and the levelized cost of electricity at 57.38 $/MWh. Furthermore, three typical biomasses were examined for the proposed system, the results showed that the dryer and carbon-richer biomass could benefit system thermodynamic and economic performance.