Two types of biofuel pellets were prepared from raw biomass and the corresponding hydrochar. Fuel
qualities of the two types of pellets including pellet density, mechanical strength and combustion char-
acteristics were investigated. The results showed that the hydrochar pellets had higher fixed carbon con-
tents, elevated heating values and enhanced mass densities in comparison to those raw biomass pellets.
The presence of extractives led to the low tensile strength of biomass pellets, while the formation of
liquid bridge and significantly enhanced attractive forces including H-bonding and van der Waal’s forces
mainly contributed to the strong bonding within the matrix of hydrochar pellets. The hydrochar pellets
combusted at elevated temperatures and wide temperature ranges compared to biomass pellets. The high
mechanical strength, low moisture uptake and improved combustion property indicated that hydrochar
pellets were more suitable than raw biomass pellets as solid biofuels. The present study demonstrated
that hydrothermal carbonization (HTC) combined with pelletization provides an alternative for solid bio-
fuel production from biomass resources, especially for the abundant agricultural residues