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Process design and economics of a flexible ethanol-butanol plant annexed to a eucalyptus kraft pulp mill

Pereira, Guilherme C.Q., Braz, Danilo S., Hamaguchi, Marcelo, Ezeji, Thaddeus C., Maciel Filho, Rubens, Mariano, Adriano P.
Bioresource technology 2018 v.250 pp. 345-354
Eucalyptus, Monte Carlo method, batch fermentation, biomass, business enterprises, butanol, energy use and consumption, enzymatic hydrolysis, ethanol, glucose, kraft pulp, markets, process design, xylose
This work proposes a strategy, from a process design standpoint, for pulp companies to enter the Brazilian ethanol market. The flexible plant converts eucalyptus-derived glucose to either ethanol or butanol (according to market conditions) and xylose only to butanol production. Depending on the biomass pretreatment technology, Monte Carlo simulations showed that the Net Present Value (NPV) of the flexible plant increases by 20–28% in relation to an ethanol-dedicated plant. Whereas the lower costs of the steam explosion technology turns the investment more attractive (NPV = 184 MMUSD; IRR = 29%), the organosolv technology provides better flexibility to the plant. This work also shows that excessive power consumption is a hurdle in the development of flash fermentation technology chosen for the flexible plant. These results indicate that conventional batch fermentation is preferable if the enzymatic hydrolysis step operates with solids loading up to 20 wt%.