residue, yielded from microalgae biodiesel production, directly. Moreover, the algal
residue may generate biogas via anaerobic fermentation. Biogas may be isolated to
refined gas and CO 2 . While the refined gas may be utilized as the conventional
energy source for daily household use, CO 2 may be recycled for algal cultivation,
which proves to be beneficial and cost effective.
3.2.2 NPV and ROI
Based on the cost and benefit data, ROI of microalgae diesel is 7.78% and the net
present value (NPV) is USD 640.
3.2.3 Sensitivity Analysis
For the sensitivity analysis, an ensemble of parameters are selected: microalgae
biomass per unit area, oil content, annual run time, recovery rate, oil extraction rate,
CO 2 absorption rate, nutrient consumption, chemical reagent consumption, and
wastewater recycling rate. The variations in microalgae diesel investment rate of
return (ROI) are estimated following a ±20% alteration in any single parameter, as
shown in Fig. 4.
Figure 4 indicates that the total price of the algae-derived biodiesel is maximally
perceptive to nutrient utilization. There is a fluctuation in the total cost from −7.56
to 10.87%, following a ±20% alteration in the lipid content. In addition, any
change in nutrient consumption strongly influences the cost. For instance, following
a ±20% change in the nutrient assimilation, the total cost change varies by a
margin of ±6%. Furthermore, following a ±20% change in either the recovery or
the oil extraction efficiency, the total cost change will vary between −4.4 and 6%.
Fig. 4 Sensitivity analysis for algal biodiesel system
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167
residue may generate biogas via anaerobic fermentation. Biogas may be isolated to
refined gas and CO 2 . While the refined gas may be utilized as the conventional
energy source for daily household use, CO 2 may be recycled for algal cultivation,
which proves to be beneficial and cost effective.
3.2.2 NPV and ROI
Based on the cost and benefit data, ROI of microalgae diesel is 7.78% and the net
present value (NPV) is USD 640.
3.2.3 Sensitivity Analysis
For the sensitivity analysis, an ensemble of parameters are selected: microalgae
biomass per unit area, oil content, annual run time, recovery rate, oil extraction rate,
CO 2 absorption rate, nutrient consumption, chemical reagent consumption, and
wastewater recycling rate. The variations in microalgae diesel investment rate of
return (ROI) are estimated following a ±20% alteration in any single parameter, as
shown in Fig. 4.
Figure 4 indicates that the total price of the algae-derived biodiesel is maximally
perceptive to nutrient utilization. There is a fluctuation in the total cost from −7.56
to 10.87%, following a ±20% alteration in the lipid content. In addition, any
change in nutrient consumption strongly influences the cost. For instance, following
a ±20% change in the nutrient assimilation, the total cost change varies by a
margin of ±6%. Furthermore, following a ±20% change in either the recovery or
the oil extraction efficiency, the total cost change will vary between −4.4 and 6%.
Fig. 4 Sensitivity analysis for algal biodiesel system
7 The Bioeconomy of Microalgal Biofuels
167