Codensification of Agroforestry Residue with Bio-Oil for Improved Fuel Pellets

Codensification of agroforestry residue with bio-oil can improve the pellet quality with reduced energy consumption and expand the utilization of bio-oil. This study comprehensively evaluates the effect of bio-oil addition on the storage, transportation, and combustion characteristics of the pellets. The results confirm that under a low pressure of 63.69 MPa bio-oils are more efficient in improving the pellet durability than selected solid additives due to the high viscosity which generated strong adhesion force during densification and enabled stronger particle interlocking of the feedstock. In addition, the hydrophobicity of the apple tree branches pyrolysis oil (APO) added pellets were enhanced, due to the introduction of hydrophobic groups and the improvements in the surface morphology. Besides, APO improved the energy density and fuel characteristics of the pellets via the change of chemical compositions. Above all, addition of the APO additive enhanced the quality of the fuel pellets. Moreover, by achieving high durability under lower pressure, the bio-oil addition could reduce the energy consumption of the densification process.