Techno-economic assessment of a wood-based biorefinery concept for the production of polymer-grade ethylene, organosolv lignin and fuel

Lignocellulose biorefineries are distinguished by an explicitly integrative, multi-functional concept that transforms biomass into multiple products, using a variety of conversion and separation processes. This study focuses on the technical design and economic evaluation of a lignocellulose biorefinery, that converts 400,000 t DM/a (≙250 MW) of beech wood into chemicals and fuel. A model was simulated with Aspen Plus® including the process steps pre-treatment, enzymatic hydrolysis, alcoholic fermentation, dehydration and biogas generation and upgrading. Mass and energy balances showed that 61,600 t/a polymer-grade ethylene, 58,520 t DM/a organosolv lignin, 38,400 t/a biomethane and 90,800 t DM/a hydrolysis lignin can be produced with a total energy efficiency of 87.1%. A discounted cash flow analysis indicated that the heat integrated biorefinery concept is not yet profitable. However, the economic results are greatly sensitive regarding various assumptions, in particular in terms of the prices for beech wood, ethylene and organosolv lignin.