A review on bioslurry fuels derived from bio-oil and biochar: Preparation, fuel properties and application

Bioslurry is an innovative renewable fuel derived from biomass. It is a blend of biochar and bio-oil through fast pyrolysis. It overcomes some issues along with the applications of bio-oil and biochar alone and has received numerous attention. In this review, we first introduced the fast pyrolysis technology for biomass, discussing application of the products as a fuel, i.e. bio-oil and biochar, focusing on the advantages and disadvantages. Then, we summarized the preparation technology of bioslurry and compared it with the conventional coal slurry technology to highlight the simplicity of the bioslurry preparation process. The characterization of bioslurry including physicochemical properties (e.g., chemical composition, homogeneity, acidity and stability) and fuel properties (e.g., water content, ash content, density, viscosity and heating value) were then systematically discussed. Furthermore, the ignition behavior and the cold flow behavior of bioslurry were presented as they were important properties when coding with special utilization environment (like cryogenic environments). The ef-fects of biochar (e.g., particle size, loading level and adsorption capacity), bio-oil and bio-oil fractions, and the addition of other chemicals (e.g., methanol, glycerol and crude glycerol) on bioslurry were discussed. Also, the applications of bioslurry including transportation, combustion and gasification were introduced which showed the advantages of bioslurry in these application fields. Finally, challenges for the further development of bio-slurry were presented, and the development directions of bioslurry were offered.