The use of renewable energy sources is becoming increasingly necessary to mitigate global warming. Recently much research
has been focused on identifying suitable biomass species, which can provide high-energy outputs, to replace conventional fossil
fuels. This paper reports an approach for increasing the yield of bio-oil production from fast pyrolysis after manipulating the
metabolic pathway in microalgae through heterotrophic growth. The yield of bio-oil (57.9%) produced from heterotrophic
Chlorella protothecoides cells was 3.4 times higher than from autotrophic cells by fast pyrolysis. The bio-oil was characterized
by a much lower oxygen content, with a higher heating value (41 MJ kg−1), a lower density (0.92 kg l−1), and lower viscosity
(0.02 Pa s) compared to those of bio-oil from autotrophic cells and wood. These properties are comparable to fossil oil. The
research could contribute to the creation of a system to produce energy from microalgae, and also could have great commercial
potential for liquid fuel production