Process simulation and techno-economic analysis for production of industrial sugars from lignocellulosic biomass

Hexose (C6 sugar) and pentose (C5 sugar) derived from lignocellulosic biomass are the precursors to bio-based fuels, chemicals and materials. This study compares the economic viability of two types of sugar products (mixed or separated C5 and C6 sugar solutions) and finds the impact of a combined heat and power (CHP) system on the economic performance. It also evaluates utilization of the residual biomass for energy recovery or carbon sequestration. For good reliability of process simulation, experimental data in the laboratory was used to simulate the pretreatment of eucalyptus wood in a diluted sulfuric acid solution. The minimum selling price (MSP) of the sugars is used as a key economic indicator. The unity production cost can be reduced by 2.2-fold with the capacity being scaled up by 100 times. A CHP system has dual effects on sugar MSP. It increases the sugar MSP by 0.03 US$ kg(-1), but reduces its sensitivity to steam price fluctuation. The sugar MSP is 0.31, 0.34, 0.38 $ kg(-1) in three scenarios (I, II and III), respectively, with a capacity of 2,000 metric tons biomass (dry) per day. The sugar MSP is most sensitive to biomass cost, followed by enzymes in Scenarios I and II. In contrast, the steam cost has the greatest impact on the MSP of separated C5 and C6 sugars in Scenario III. If the residual biomass is not burned for energy recovery, a carbon tax credit could be an additional revenue to reduce the sugar MSP by 20 %.