0.3 = 10,800MWh/month. By contrast, solar bio-oil CSP is only
0.19%, the energy productivity of a 50 MW solar CSP plant. However,
solar bio-oil only requires 2 ha of land, whereas a 50 MW
solar CSP electricity plant requires 150 ha. 2 ha of solar electricity
CSP would produce 144MWh and therefore solar bio-oil CSP is
20.4/144 = 14% the efficiency of electricity solar CSP. Further considerations
of the energetic comparisons are the energy versatility
of the liquid fuel for transportation requirements, recycling of
nutrient water solubles back into the microalgae culture ponds
to improve productivity and capital investment economics. There
is additional scope for an improvement of the energy return on
energy invested of algae HTL with recycled heat from the combustion
of bio-oil and gas by-products.
Table 7 shows 2 trials and 4 microalgae production costs
[44,45]. The Dutch economic productivity investigation forecast
with an inflation rate of 5% used microalgae costs of €0.7/kg based
on growth in the Dutch Antilles in the tropics [45]. By contrast,
another economic evaluation of cost of microalgae production in
Spain indicated a production cost of €69/kg. This is due to higher
operational and processing costs including carbon dioxide, synthetic
nutrients, centrifugation, freeze-drying and labour costs. It
was concluded by the Spanish trial that process automation, lowlabour
costs, waste flue-gases and waste nutrients could reduce
production costs further [46].
CSP is still a relatively young and actively researched technology.
Table 8 shows the incremental commercial production interest
and amplified scale in commercial systems within the last
5 years. CSP/HTL research could complement this field.
There exist various parameters’ affecting the conversion of biomass
into bio-oil. Coordination of biomass input and bio-oil output
within the scope of this TEA requires reliable definition of biomass