Low-Cost Production of Sustainable Aviation Fuels (SAF) from Perennial Feedstocks using Simultaneous Ball Milling and Enzyme Hydrolysis (STTR)

The objective of this Alternative Use of Commercial Equipment Phase 1 project is to optimize a simultaneous ball milling/enzyme hydrolysis process that would replace separate pretreatment and hydrolysis processes in the production of Sustainable Aviation Fuels (SAF). This process uses existing ball milling equipment that would be optimized for biomass hydrolysis. The 2021 Government-Wide Sustainable Aviation Fuels Grand Challenge, which includes SAF production goals of 3 billion gallons by 2030 and 35 billion gallons by 2050, as well as provisions of the Inflation Reduction Act of 2022 will drive international demand for SAF. Our DOE Phase I work plan builds on successes from our Maryland Energy Innovation Institute (MEII) work. These include: 84% of residual hemp biomass carbohydrates were converted to fermentable sugars without pretreatment, pectinase used to hydrolyze pectin improved cellulose conversion ratios by 13%, and USDA/ARS E. coli FBR5 bacteria converting both five and six-carbon sugars to ethanol at rates 20% better than glucose, the process could provide an effective ethanol source for SAF process used by firms including GEVO, Vertimass, and LanzaJet. In addition to demonstrating biomass to fermentable sugars, this work also identified significant improvements that are needed to make our process more commercially viable for SAF and related production, including: ? Maximize biomass processing quantities per enzyme quantity. ? Improve fermentable sugar recovery. ? Use heterogeneous biomass feedstocks. ? Reduce processing times. ? Use feedstocks stored for different periods of time (fresh to up to a year). ? Reduce milling ball quantities to reduce container wall and weight requirements to reduce energy and capital equipment costs. In this Phase I project, a five task work program will be undertaken to develop these improvements. Perennial energy grasses that can be grown on marginal lands will be tested. In addition to switchgrass, Miscanthus or Phragmites will be tested. Switchgrass and Miscanthus grasses will be provided by the Association of Warm Season Grass Producers.