Unlocking the Biofuel Power of Cover Crops in Washington State: Enhancing Potential Through Hydrothermal Liquefaction

Abstract

In the Pacific Northwest, cover crops are typically cultivated during the shoulder seasons – specifically, late fall and early spring, when agricultural land is often fallowed. Crops like legumes and grass have been shown to enhance soil quality, yet a recent survey of farmers in Washington state indicated that low adoption rates are largely attributed to limited knowledge and cost-related barriers. Cover crop feedstocks represent an opportunity to access economically viable and environmentally advantageous sources for biofuel production while decreasing both the carbon and chemical intensity associated with conventional agricultural practices. This study aims to deepen the understanding of the optimal cultivation of cover crops for biofuel production via the hydrothermal liquefaction pathway. However, it is essential that removal of the cover crops does not negatively impact soil health or the productivity of subsequent cash crops. To assess the economic and environmental feasibility of biofuel production from cover crops, a techno-economic analysis and life-cycle assessment were conducted based on 3 years of data collected in two locations in Washington state (Puyallup and Othello) related to growing cover crops prior to cash crops. In addition to benefitting farmers, the findings suggest that biofuel production through hydrothermal liquefaction may not only be economically advantageous in supplying more fuels, but it also reduces carbon intensity by at least 70% compared to petroleum-based fuels.

Keywords: Hydrothermal liquefaction, biomass, Cover crops, biofuels, technoeconomic analysis, life cycle analysis