Thermodynamic analysis of biomass-driven polygeneration plants with biogenic CO2 utilization: Comparative assessment of various thermochemical conversion technologies

As a promising solution to offset emissions from carbon-intensive and hard-to-abate sectors, bioenergy conversion with carbon capture and utilization (BECCU) technologies play a vital role in achieving carbon-negative emissions. This study is aimed at developing complete BECCU process chain models by integrating thermochemical and electrochemical conversion processes and evaluating their biomass-to-power (BtP, ηIII,BtP), biomass-to-liquid (BtL, ηIII,BtL), and overall BECCU (ηIII,overall) conversion efficiencies. The BtP system is coupled with oxy-fuel combustion technology to yield concentrated CO2, which is then used as a carbon source in the CCU process (i.e., power-to-liquid). Three integrated biomass-based polygeneration systems are compared for BECCU applications, considering gasification (Scenario 1), pyrolysis (Scenario 2), and oxyfuel combustion (Scenario 3). Simulations indicate that Scenario 1 achieves the highest overall BtP efficiency (ηIII,BtP) of 21.5%, which is 12.9% and 3.2% higher than those of Scenarios 2 and 3, respectively. In contrast, Scenarios 1 and 3 exhibit nearly equivalent overall BECCU efficiencies (ηIII,overall) of 45.7% and 45.6%, respectively, whereas Scenarios 2 shows the lowest efficiency (21.3%). However, considering the environmental performance, Scenarios 2 exhibits the lowest specific CO2 emissions, as biogenic carbon is retained in biochar as a long-term carbon sink. A net CO2 removal of approximately 0.18 kg-CO2/kg-rice straw can be achieved within a gate-to-gate system boundary. Therefore, among the three cases, Scenario 2 likely represents the most environmentally beneficial pathway with the strongest potential for achieving carbon-negative polygeneration systems.