An optimization model for a biorefinery system based on process design and logistics

Design of biorefineries has been often addressed by process flowsheet optimization tools without adequately considering the relevant supply chain network. In this work, an integrated optimization algorithm including the biorefinery process flowsheet structure and biobased supply chain network was developed. A superstructure of different process pathways for a biorefinery co-producing ethanol, ethyl levulinate and electricity is built on the base of up-to-date technologies. The bio-based supply chain model was implemented to address the transportation, the inventory management and the size of the biorefinery. Mixed Integer Linear Programming (MILP) was used as a modeling approach. The efficiency of the algorithm was demonstrated by applying it to a case study consisting of a wheat straw supply chain network for bioproducts demand in Germany. The algorithm reached convergence after three iterations providing a final optimal number of biorefineries distributed in different regions of the country corresponding to a maximum Net Present Value.