This sized CSP plant could process 200 kg of daily microalgae
biomass in 3 cycles. The schematic diagram of the solar-assisted
HTL plant is depicted in Fig. 1, which describes the integration of
solar CSP with the tubular HTL reactor aligned along the focal line
of the parabolic trough.
A land surface area of a 1 ha site could produce in the region of
180–200 kg biomass per day from a high rate microalgae pond,
additional waste biomass and recycled nutrients for secondary biomass
growth further supplements HTL microalgae feedstock. Considering
a 30% biomass to bio-oil conversion with a ratio of 20%
solids to water ratio in HTL, this would provide 1000 l feedstock
per day. The HTL reactant volume space replaces the heat transfer
fluid (HTF) as used in conventional electricity generating CSP
plants. Likewise, HTF molten salt is replaced by microalgae biomass
and water as the reactant components of HTL. Reactant
inputs and discharge on alternative ends of each linear row of parabolic
troughs function as semi-continuous batch processing. A proposed
diurnal thermal HTL capacity for 3 h either side of midday
permits 3 batch runs per day (Table 4). Estimation of CSP plant size
for processing of HTL feedstock is based on the 1000 l daily production
of HTL feedstock at 20% (w/v) microalgae – 160 l HTL reaction
core volume from 100 m of