CHAPTER 4: Integrated Forest Biorefineries: Product-Based Economic Factors

Chemicals and fuels produced from at a biorefinery require complex operations and often specialized equipment, especially in those cases where a hybrid process includes both biochemical operations (utilizing the carbohydrate content of the feedstock) and thermochemical processes (utilizing the residue after some or all of the carbohydrate has been removed). Given that the products of the two types of operation are not entirely fungible, comparative studies on the optimal balance of products from a biorefinery can be difficult. Because biochemical processes normally require a particular feedstock (monomeric sugars in solution) while thermochemical processes are relatively feedstock insensitive, it stands to reason that an optimization of an integrated process that includes both types of operation is possible by examining the downstream effect of variations in early process parameters. The question is essentially, can yield sacrifices in feed preparation for biochemical operations be recouped by lower operational costs and/or higher-quality thermochemical products? Examining the output of a biorefinery in terms of relative difficulty in processing and subsequent level of operational cost in the design phase can aid in making decisions about process paths, and potentially make the case for more operational flexibility.