Comparatively, the pyrolysis sub-process is 51% efficient in the
conversion of embodied feedstock energy to bio-oil, Fig. 5(B). The
pyrolysis sub-process is integrated into a bio-refinery system
allowing for energy recovery through a heat exchanger and combustion
of pyrolysis byproducts, char and gasses. Recovered energy
accounts for 28% of the embodied energy in the feedstock, and is
used to supplement the energy demand of the drying unit and
heating demands in the reactor. Recovered energy helps the overall
energetics of the system, but does not negate the energy demands
for drying the microalgae biomass or heating in the reactor. Even
with energy recovery the combination of the energy demands in
the drying unit and pyrolysis reactor are too large for microalgae
conversion through pyrolysis to be made energetically favorable.