(402n) Valorizing Lignocellulosic Biomass to Sustainable Aviation Fuel: Integrating Life Cycle Assessment with Technoeconomic Analysis Under Uncertainty

Anthropogenic emissions from aviation contribute to roughly 3% of the total U.S. GHG emissions. The aviation sector is exceptionally difficult to decarbonize due to the challenge of designing batteries with energy densities comparable with liquid fuels while adhering to aircraft weight constraints. Energy-dense liquid fuels will likely play a crucial role in fueling large aircraft for the foreseeable future. Sustainable Aviation Fuel (SAF) derived from lignocellulosic biomass offers the promise of substantial reductions in greenhouse gas (GHG) emissions and increased domestic energy production in countries with sufficient biomass resources. Multiple conversion pathways to produce SAF blendstocks have been ASTM approved including Hydroprocessed Esters and Fatty Acids (HEFA), Fischer-Tropsch (FT), and alcohol to jet (ATJ). While HEFA is the most commercially mature pathway and could potentially represent 70% of total SAF production capacity by 2030, concerns arounds its rising bio-feedstock prices and availability incentivizes SAF producers to explore other promising routes. The HEFA pathway also produces both renewable diesel (RD) and SAF hydrocarbon fractions, and current market and policy favor RD productions which limit its potential for SAF production. ATJ involves building large molecules from small molecules and therefore can be directly used to produce SAF range blendstocks. For FT synthesis, gasification technology is nascent and needs to overcome certain technical and process challenges to achieve commercialization.

This study focuses on the Alcohol-To-Jet (ATJ) pathway, using cellulosic ethanol to produce a SAF blendstock with renewable naphtha as a co-product. While previous studies have modelled the ATJ process and have determined performance indicators such as the Minimum Selling Price (MSP), they have based their analysis off average values of key process inputs. This approach overlooks the inherent uncertainty associated with the process variables and can provide misleading results about the economic and environmental sustainability of ATJ. Herein, we develop an open-source refinery scale model leveraging BioSTEAM (Biorefinery Simulation and Techno-Economic Analysis Modules), which integrates process design with technoeconomic analysis (TEA), and life cycle assessment (LCA). This model was validated with results from Aspen Plus V12.1 – a commercial process simulation tool. A robust analysis revealing potential tradeoffs between economic viability and sustainability under uncertainty is presented. Overall, this study aims to provide improvement opportunities for SAF biorefinery research and development (R&D) efforts.