(438d) Spatial Trade-Offs in Designing a Sustainable Cellulosic Biofuel Supply Chain: Insights from High Resolution Modelling

Cellulosic biofuel produced from dedicated energy biomass requires crops to be established on marginal lands, new facilities to be constructed, and large supply systems to be designed to connect the upstream and downstream portions of the process. The cellulosic biofuel supply chain (SC) is highly interconnected and the design and operational decisions, all the way from field to product, need to be considered simultaneously and at a high spatial resolution to account for the trade-offs among different components of the system.

In this work, we use a high resolution mixed-integer linear programming model to analyze the spatial trends that arise when designing a system to produce liquid cellulosic biofuel in the US Midwest. Because greenhouse gas (GHG) mitigation is one of the primary goals of producing liquid biofuel, we use the epsilon constraint method to find pareto-optimal solutions for a range of biofuel demands. Upstream, model decision variables determine biomass establishment, fertilization, and harvesting at the field level which influence the yield and soil carbon sequestration. Downstream, we consider 3 primary conversion pathways at the biorefinery including fermentation to ethanol, pyrolysis, and gasification and explore the option to install carbon capture and storage (CCS) technologies to capture and sequester CO₂ from a variety of process streams with a range of CO₂ concentrations.

The results of our analysis show that landscape design, choosing where to establish biomass crops and how to manage them, has a large impact on the GHG balance of the system especially at restrictive epsilon constraints. We show that the technology portfolio at the biorefineries is dependent on the location of each facility, the spatial trade-offs between the local price and GHG impact of electricity, the bioenergy landscape design, and the cost to capture, transport, and sequester CO_2. Finally, we offer insights into the SC network design and operational strategies to meet a range of biofuel demands under different epsilon constraints.