In addition to operating parameters, the nature of biomass, i.e.,
different components of cellulose, lignin, protein and fat, significantly
impacts the yield and chemical composition of the HTL
products. To date, most of studies examined the lignocellulosebased
feedstock (e.g., forest residues, agricultural wastes), which
contains a relatively high content of lignin while low contents of
lipid and protein [27e30,50]. The HHVs of the HTL bio-oils obtained
from the lignocellulose biomass (without using any catalysts and
organic solvents) are in the range of 30e36 MJ kg1, and the oil
yields are relatively low (20%e36% mass fraction). These studies
indicated that a high content of lignin in feedstock was not desirable
for the bio-oil production. Recently, it was observed that high
lipid and protein contents in feedstock benefited the yield and the
quality of the bio-oil [41e48,51,52].