3. Results and discussion
3.1. Economic results
The economic results are presented in Figs. 3–5. The TEA
(Techno-Economic Analysis) assumes an equipment lifecycle of
20 years. The TEA model estimates that with a CAPEX of $242K,
OPEX (Operating Expenses) of $43K/year and bio-oil product of
70 tonnes/year from a 1 ha site a MFSP (Minimum Fuel Sales Price)
of $1.23/kg bio-oil Table 5. This TEA is based on a processing system
which simplifies feedstock processing capacity by integrating
the solar heat directly with the solar collector. The system requires
the implementation of pressure release valves before and after the
reactor core to allow for incremental heating and passive cooling
during the 2 h semi-continuous batch reaction. The HTL reactor
and the solar collectors constitute 69% of the total capital investment.
Main CAPEX costs of the pond construction is made up of
containment geomembrane liners. The economic assessment does
not include further downstream processing such as liquid, gas and
solid separation or hydro-process upgrading of biofuel via catalytic
hydrogenation. Operating labour costs account for 46% of OPEX,
followed by overheads 23%, maintenance 16% and feedstock raw
materials 12%.
Direct comparison between CSP DSG (Direct Steam Generation)
and CSP HTL is valid as the only difference between the solar field
components of the HTF is the replacement of water with microalgae
and water at 20% inclusion (w/v). Replacement of HTF using
DSG is not yet widely applied commercially for CSP electricity generation.
The major bottleneck constraint to the use of DSG instead