While the potential of hydrothermal liquefaction (HTL) of microalgae to produce biocrude regardless of
the types of microalgae (biomass-agnostic) has been noted, the quality of biocrude and the Energy Return
On Investment (EROI) of HTL of various microalgal species have not been compared in detail. Here we
report that the quality of biocrude and the EROI of microalgal HTL are directly dependent on the lipid contents
of microalgae. When Nannochloropsis oceanica (30.2% lipid content) and Golenkinia sp. (17.3% lipid
content) were compared for the quality of HTL in terms of the total yield, asphaltene/non-asphaltene contents,
heteroatom (O, N, and S) concentrations, and the effective hydrogen-to-carbon ratios (H/Ceff) of the
biocrudes, N. oceanica with high lipid content produced biocrude that can be more suitable for catalytic
upgrading to transportation fuels than the biocrude from Golenkinia sp. with low lipid content. HTL of N.
oceanica at low temperature (200 C) in particular produced the biocrude with EROI that was better than
that of Golenkinia sp. These results strongly support that the choice of microalgae with high lipid content
is still a key factor that must be considered for biocrude production as much as it is regarded important
for biodiesel production using microalgal biomass.