The comparative techno-economic and life cycle assessment for multi-product biorefinery based on microwave and conventional hydrothermal biomass pretreatment

Microwave as an efficient and clean energy, is easy integrated with DES pretreatment and biorefinery process to achieve process intensification for cleaner production and sustainable development. However, there are worries about its economic and environmental feasibility for application in biorefinery plant. This work conducted the techno-economic (TEA) and life cycle assessment (LCA) of the entire biorefinery process based on DES pretreatment by microwave heating (MH) for producing glucose, furfural and lignin from lignocellulose, of which the results were compared with conventional heating (CH). For pretreating equivalent biomass, the total yield of products obtained from MH-assisted process was 8.53% higher than that of CH-assisted process due to microwave intensification effect. From the perspective of cradle-to-gate LCA, the MH-assisted process saved energy demand of 5.82%, reducing the environmental impacts global warming (GW) and fossil resource scarcity (FRS) by 4.85% and 5.69%, respectively, relative to CH-assisted process. The main environmental hotspots of both two processes concentrated on the raw material extraction (RME), followed by product separation and solvent recovery (PSSR) stages. Based on economic evaluation, the specific values of TAC regarding one-ton product for MH- and CH-assisted processes were 3194.35 and 3400.37 $/(y⋅t), respectively. Therefore, the MH-assisted pretreatment possessed certain environmental and economic advantages due to product increasement, energy consumption reduction in the DES pretreatment, and burden reduction for subsequent enzyme hydrolysis. Compared to the single-product biorefinery, the multi-product biorefinery strategy was more sustainable and could maximize the advantages of microwave intensification. However, some issues about the design of microwave reactors and temperature monitoring must be considered to pursue scale-up biorefinery plant.