Study on the biomass-based integrated gasification combined cycle with negative CO2 emissions under different temperatures and pressures

Highlights: • The biomass gasification combined cycle and oxy-fuel combustion are integrated. • The effect of gasification pressure and temperature on system performance is studied. • The thermodynamic analysis of each subsystem is carried out to evaluate the system. • The negative CO₂ emissions are achieved with a competitive efficiency. -- Abstract: To reduce the carbon emissions in power sector, a biomass-based integrated gasification combined cycle (BIGCC) with oxy-fuel combustion is proposed. The syngas generated from biomass gasification is burned under oxy-fuel atmosphere for power generation, and CO₂ in the flue gas is captured by merely cooling. Thus, the negative CO₂ emissions are realized considering the carbon neutral character of biomass. The effects of gasification temperature and pressure on syngas composition and system performance are investigated. The results show that rising pressure and temperature lead to lower H₂ and CO production, while CO₂ and CH₄ generation are enhanced with higher pressure and lower temperature. The system efficiency increases with the pressure rise, while it fluctuates with the temperature variation. The optimum temperature and pressure of gasification is 1000 °C and 3.5 MPa. The corresponding energy and exergy efficiency is 35.41% and 31.21%. The thermodynamic analysis is carried out for each subsystem. The energy loss and exergy destruction is 76.2% and 55.4% for gasifier and 21.8% and 31.3% for HRSG. Considering the unavoidable energy and exergy consumption in gasification, the system optimization can be concentrated on HRSG. The efficient power generation and significant carbon emissions reduction are achieved in the proposed system.