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

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.