Influence of specific light availability and solvent on process economics — The production of fucoxanthin and eicosapentaenoic acid from P. tricornutum using flat-panel airlift photobioreactors with artificial light

This study presents an economic assessment of an up- and downstream process (USP and DSP) using P. tricornutum in flat-panel airlift photobioreactors (FPA-PBRs) with artificial illumination. Depending on the solvent, it is possible to obtain separately a crystalline fucoxanthin and eicosapentaenoic acid-rich (EPA) oil or a fucoxanthin- and EPA-rich oleoresin. The objective was to investigate the potential of optimizing light supply during USP and changing the extraction solvent during DSP to reduce fixed capital investment (FCI) and production costs. Comprehensive experimental data on the cultivation of P. tricornutum and the extraction and separation of the products were used to perform techno-economic assessments (TEA) and profitability analyses of different scenarios. In the first part, six scenarios were developed to determine the economic performance with a biomass concentration (c0) of either 3.0 or 6.0 g l−1 and a specific light availability (Ispec) of 2.0, 5.0 or 8.0 μmolphotons g−1 s−1 during the annual production of 10.0 t fucoxanthin ((component of biomass) until harvest. In the second part, the scenario with the economically most favourable results served as the basis for TEA depending on the solvent. It was demonstrated that production costs of dry weight biomass (CX) could be reduced from 644.31 to 184.30 € kgDW−1 by increasing Ispec and volumetric biomass productivity (QX) with the lowest biomass yield on light energy (YX,ph). A sensitivity analysis was performed to evaluate the possibilities of reducing costs and increasing profitability. Increasing QX proved to be the most effective, resulting in a decrease in CX of up to 20.1 %. Subsidising the FCI was most effective in reducing FCI, resulting in a decrease of up to 49.6 %. By using ethanol instead of a nonpolar solvent, the specific production costs of fucoxanthin (CFx) could be decreased by 60.0 % from around 39,825 € kgFx−1 to 16,111 € kgFx−1.