(318b) Unlocking the Potential of Cover Crops in the Pacific Northwest: Economic and Environmental Perspectives on Biomass-to-Biofuel Via Hydrothermal Liquefaction

Cover crops offer numerous benefits, such as improving soil health, reducing erosion, and enhancing cash crop yield potential, yet their adoption remains low in the Pacific Northwest. To demonstrate to growers the benefits of cultivating cover crops, it is important to investigate the economic and environmental impacts of their adoption and ensure that their harvest does not adversely affect soil health or subsequent cash crop yields. Additionally, identifying feasible conversion technologies is essential for effective cover crop utilization.

In this context, we present techno-economic analysis (TEA) and life-cycle analysis (LCA) for biofuel production from cover crops via hydrothermal liquefaction (HTL). HTL has emerged as a promising biofuel technology for wet waste (i.e., sewage sludge, manures, and food waste), as it eliminates the energy-intensive drying process often required by other biomass conversion technologies. This work investigates: i.) blending scenarios of cover crops and sludge, and ii.) cover crop feedstock cost (grower payment) and their subsequent impact on biocrude oil yields and fuel production economics. The HTL plant is designed to convert 110 dry tons/day of waste into biocrude, which is then transported to a centralized biocrude upgrading plant to produce a biofuel blendstock (naphtha/diesel/jet fuel).

Primary data on growing cover crops (i.e., hairy vetch, fava, triticale, crimson clover, and winter pea) in between cash crops was collected over three years in two locations in Washington State (Puyallup and Othello). This data is used for compositional analysis and oil yield predictions for feedstock blending estimations. These analyses aim to identify opportunities for increased cover crop utilization from both growers’ and biofuel producers’ perspectives. Initial estimates indicate that combining sludge and cover crops for HTL could facilitate more resilient and flexible biofuel supply chains, with the potential to achieve <$3.5/gge and >70% reduction in GHG emissions compared to petroleum-based fuels.