Bioslurry as a Fuel. 4. Preparation of Bioslurry Fuels from Biochar and the Bio-oil-Rich Fractions after Bio-oil/Biodiesel Extraction

In this study, bio-oil is extracted using biodiesel to produce two fractions: a biodiesel-rich fraction (also referred as biodiesel/bio-oil blend) and a bio-oil-rich fraction. The results show that the compounds (mainly phenolic) extracted from bio-oil into the biodiesel-rich fraction reduce the surface tension of the biodiesel/bio-oil blends. The bio-oil-rich fraction is mixed with ground biochar to produce a bioslurry fuel. It is found that the bioslurry fuels with 10 and 20% biochar loading prepared from the bio-oil-rich fraction of biodiesel extraction at a biodiesel/bio-oil blend ratio of 0.67 have similar fuel properties (e.g., density, surface tension, volumetric energy density, and stability) in comparison to those prepared using the original whole bio-oil. The slurry fuels exhibit non-Newtonian with pseudo-plastic characteristics and good pumpability, desirable for fuel handling. The viscoelastic behavior of the slurry fuels also shows dominantly fluid-like behavior in the linear viscoelastic region, therefore favorable for atomization in practical applications. This study proposes a new bio-oil use strategy via co-production of a biodiesel/bio-oil blend and a bioslurry fuel. It is known that the biodiesel/bio-oil blend can be used as a liquid transport fuel, using a proportion of bio-oil compounds (relatively high value and small volume). The bioslurry fuel is prepared by mixing the low-quality bio-oil-rich fractions (relatively low value and large volume) with ground biochar, suitable for stationary applications, such as combustion and gasification.