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Technoeconomic assessment of an innovative thermochemical route to produce ethanol from lignocellulosic biomass

Abstract:

This paper presents a techno-economic assessment of a BTL plant that processes 2140 dry tonne/day of poplar chips (500 MWHHV) to produce thermochemical ethanol from biomass via DME hydrocarbonylation. Biomass is gasified in an indirect circulating fluidized bed gasifier modeled with experimental correlations from the Battelle Columbus Laboratory Gasifier. After gas cleaning and conditioning, the indirect catalytic synthesis route to ethanol comprises three reaction steps: methanol synthesis, methanol dehydration to DME (both commercial technologies) and DME hydrocarbonylation to ethanol (a non-commercial process still under development). Data for the hydrocarbonylation reaction step were extracted from recent publications (Zhang, 2010). The technoeconomic assessment was done according to design and economic criteria accepted worldwide for BTL processes and imposing the condition that the whole process should be energy self-sufficient and "electrical energy neutral". Five simulation cases of varying CO-to-DME ratios in the hydrocarbonylation reactor were performed and evaluated. The results show that this is a promising indirect route that can achieve a minimum selling price (10% internal rate of return) of 0.735-0.802 USD2010/L of automotive grade ethanol with a fixed capital cost of 501-531 MM USD2010. Biomass-to-ethanol energy efficiency ranges from 43 to 45% on a high heating value basis (HHV).