Technoeconomic Analysis of Ethanol Production from Corn Stover without Solid–Liquid Separation and Detoxification

Abstract

Water and chemical overconsumption is one of the technical challenges for cellulosic ethanol production. To address this issue, a facile process, where Ca(OH)2-pretreated corn stover slurry is subjected to pH adjusting with H2SO4 for ethanol fermentation by C6 (scenario I) or C6/C5 (scenario II) yeast, is proposed. This study demonstrates its experimental feasibility for ethanol production without solid–liquid separation and detoxification, thus effectively reducing the consumption of water and chemicals. Technoeconomic analysis shows that total capital investment ranges from $127.86 million to $134.82 million with a production capacity of 90 Mt/h for 7920 h annually. Raw material (43.22–44.62%) and utility (35.49–37.23%) costs play important roles in annual operating costs. The pretreatment and fermentation section contributes $2.12/gal for scenario I and $1.61/gal for scenario II to the net unit production cost of ethanol. The ethanol minimum selling prices (MSP) of $4.01/gal for scenario I and $3.16/gal for scenario II are reached with an internal rate of return of 10%. Sensitivity analyses indicate that the costs of corn stover and water for cooling are the dominant elements affecting ethanol MSP.