productivity at scaled production. Commercial microalgae biomass
production is dominated by extremophile species tolerant of wide
ranges of pH, temperature or salinity [51]. This TEA study integrates
biomass input (productivity) with bio-oil output (HTL conversion),
hence estimates land area, equipment costs and
conversion efficiency into a dynamic economic model which provides
a predictive forecast range for further applied experimental
work. One of the only feasible energetically efficient conversion
pathways for the production of fuel from microalgae is whole
microalgae biomass using thermochemical conversion, by contrast
energy efficient conversion of biodiesel transesterification is compromised
by water and petroleum derived solvent evaporation
[52]. Bio-oil from HTL does not use embedded energy from petroleum
derived substances, and input heat energy could be supplied
via CSP. With optimised heating to reaction temperature, cooling
to ambient temperature, efficient filling and emptying of the reactor
it is feasible that more than 3 semi-continuous batch processes
could be run per day. Furthermore, optimal site location, CSP
geometry, and solar concentrator tracking could enhance productivity
and conversion efficiency beyond that reported in this study.
Biomass input into this CSP/HTL design does not have to be solely
of microalgae origin, as HTL has found to have been effective with
other feedstocks including swine manure [17], macroalgae [27]
and E. coli [32]. The unification of CSP and HTL described herewith
and not previously reported by other authors’ provides scope for
further work to evaluate the practical implementation of this
research.