A process economic approach to develop a dilute-acid cellulose hydrolysis process to produce ethanol from biomass

Successful deployment of a bioethanol process depends on the integration of technologies that can be economically commercialized. Pretreatment and fer mentation operations of the traditional enzymatic bioethanol-production pro cess constitute the largest portion of the capital and operating costs. Cos t reduction in these areas, through improved reactions and reduced capital, will improve the economic feasibility of a large-scale plant. A technoeconomic model was developed using the ASPEN Plus(TM) modeling soft ware package. This model included a two-stage pretreatment operation with a co-current first stage and countercurrent second stage, a lignin adsorptio n unit, and a cofermentation unit. Data from kinetic modeling of the pretre atment reactions, verified by bench-scale experiments, were used to create the ASPEN Plus base model. Results from the initial pretreatment and fermen tation yields of the two-stage system correlated well to the performance ta rgets established by the model. The ASPEN Plus model determined mass and en ergy-balance information, which was supplied to an economic module to deter mine the required selling price of the ethanol. Several pretreatment proces s variables such as glucose yield, liquid: solid ratio, additional pretreat ment stages, and lignin adsorption were varied to determine which parameter s had the greatest effect on the process economics. Optimized values for th ese key variables became target values for the bench-scale research, either to achieve or identify as potential obstacles in the future commercializat ion process. Results from this modeling and experimentation sequence have l ed to the design of an advanced two-stage engineering-scale reactor for a d ilute-acid hydrolysis process.