(94a) Producing Biocrude from Renewable Feedstocks through Hydrothermal Liquefaction

To maintain sustainability with respect to people, prosperity, and the planet, we must produce liquid biofuels from renewable and sustainable resources at a price that is competitive to petroleum derived fuels. Based on this motivation and market need, we have successfully developed a straightforward but highly efficient process to produce biodiesel from an oleaginous yeast strain, Cryptococcus curvatus grown on hydrolysate of sweet sorghum bagasse. The simple pretreatment of using 0.5% sulfuric acid at 121 ^oC for 1 h released 92.2% of theoretically available sugars in sorghum bagasse. The yeast strain thrived on the hydrolysates and accumulated lipids to an extent of 48% of dry cell weight. Through a one-step in-situ transesterification reaction using microwave energy, 92.0% of lipids in wet cells of C. curvatus were converted to crude biodiesel under an optimal condition.

 The bagasse-to-biodiesel pathway is certainly ready to be scaled up. However, using this pathway, yeast cell residues (YCR) after transesterification and the pretreated and washed bagasse (PWB) following pretreatment are generated. To utilize these two materials, we seek to empoly hydrothermal liquefaction (HTL) to convert both to biocrude considering two reasons: (1) compared with other thermochemical processes, HTL is conducted at a relatively low temperature of 250-350^oC; and (2) liquefaction can handle materials with any levels of water content. Thus, for the two target materials with moisture content of around 80%, HTL is an excellent choice. In this talk, we will present our recent results on HTL of these two biomaterials with different catalysts. Yields of biocrude and biochar from each material will be presented. In addition, the properties of the biocrude samples will be reported. The characterization of the resulting aqueous phase samples will be detailed, too. Our results have shown that biofuels can be developed successfully from renewable and domestic feedstocks through a combination of biochemical and thermochemical processes.