Techno-economic analysis (TEA) and life-cycle assessment (LCA) methodology as a tool for biorefining technology benchmarking and iterative process design

A systematic methodology for the comparison of selected biorefining pathways to produce sugars and lignin from hardwood (HW) chips was developed. Two acid hydrolysis pathways (dilute, concentrated sulfuric acid) and six enzymatic hydrolysis pathways (extrusion, steam explosion, acidic and alkaline sulfite treatment, refining with alkaline treatment, multi-stage milling) were assessed on the basis of technical, economic and environmental factors. Process designs were developed based on experimental and literature data for a commercial biorefinery treating 150 t/d of dry hardwood feedstock. All processes were modeled using ASPEN Plus® simulation software to generate a complete mass and energy balance. Total Investment Cost (TIC) estimation, economic analysis (TEA) and life cycle analysis (LCA) were performed, and results were consolidated in a multi-criteria matrix analysis tool. Acid hydrolysis pathways were noted to have lower operating and investment costs, although technical risks related to lower yields, sugar quality and uncertain performance of acid recovery units were identified. TIC and minimum selling price (MSP) of sugars were in a similar range for many of the enzymatic hydrolysis pathways and challenging economics are noted. LCA was conducted for all pathways with an emphasis on carbon footprint (CO₂ eq/t sugars) and hot-spot analysis. The results highlighted the need for energy integration and biogenic energy sources to mitigate carbon impacts. Pathways with higher carbon intensity were flagged and related hot spots were identified.