nutrients and algal productivity, will also affect the total cost. In general, the cost of
biofuels, such as algae-derived ethanol, is still higher than that of the fossil oils.
The revenue brought by algae-derived ethanol project is USD 8020/ton, which is
higher than the cost. The revenue corresponding to the algae-derived biofuel may
be credited to two segments: the products and the cost savings. The products are
mainly ethanol, syngas, other liquids, and biomass, generating USD 370,615;
47,607; 1,073,089; and 1,628,041 per annum, respectively. As the
wastewater-based microalgal biofuel production system recycles, nutrients like
nitrogen and phosphorus may be recycled for microalgal growth to synthesize
biofuels, which also gains USD 564,768 annually via the saving costs. Moreover,
USD 46,883 may be earned as the carbon credit, because algae can absorb CO 2
during its growth period.
3.1.2 NPV and ROI
Assuming the discount rate to be 8%, the annual NPV is estimated to be USD
2.69 million, suggesting that the project is worth investing. The project ROI is
17.57%, which is higher than the discount rate, and implies that the algae-derived
biofuel project possesses good economic benefits.
3.1.3 Sensitivity Analysis
The analysis has been performed via selection of PBR cost, salaries, operating
period, chemical consumption, energy consumption, and biomass price as parameters, to evaluate their impressions on the economic cost, subject to an increase or
decrease by 20% (Fig. 2).
The cost of algae-derived biofuel is most sensitive to the biomass price. The
rising selling prices of biomass will greatly increase the profits of products and
byproducts, ultimately lowering the actual economic cost. A 50.15% rise in the cost
has been estimated, following a 20% increase in the biomass selling price. Thus,
improving cultivation technology and promoting microalgae recovery efficiencies,
oil extraction, and conversion rate, are a few effective approaches to enhance the
economic performance.
In addition, the impacts of PBR cost, and operating period of the system on
actual economic cost are significant. PBR is one of the principal project devices and
incurs high expenses as well. It is anticipated that the breakthrough in the procurement of equipment, as a result of scientific and technological progress, will
eventually reduce the cost of equipment input. Moreover, operation time constitutes
a significant factor, having substantial connections with investments including the
rental price of the land, energy, chemical and nutrient consumption, and wastewater
cycling rate. A *14% increase in the tangible cost is probable, provided the
operation time is cut down by 20%.
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K. Peng et al.
biofuels, such as algae-derived ethanol, is still higher than that of the fossil oils.
The revenue brought by algae-derived ethanol project is USD 8020/ton, which is
higher than the cost. The revenue corresponding to the algae-derived biofuel may
be credited to two segments: the products and the cost savings. The products are
mainly ethanol, syngas, other liquids, and biomass, generating USD 370,615;
47,607; 1,073,089; and 1,628,041 per annum, respectively. As the
wastewater-based microalgal biofuel production system recycles, nutrients like
nitrogen and phosphorus may be recycled for microalgal growth to synthesize
biofuels, which also gains USD 564,768 annually via the saving costs. Moreover,
USD 46,883 may be earned as the carbon credit, because algae can absorb CO 2
during its growth period.
3.1.2 NPV and ROI
Assuming the discount rate to be 8%, the annual NPV is estimated to be USD
2.69 million, suggesting that the project is worth investing. The project ROI is
17.57%, which is higher than the discount rate, and implies that the algae-derived
biofuel project possesses good economic benefits.
3.1.3 Sensitivity Analysis
The analysis has been performed via selection of PBR cost, salaries, operating
period, chemical consumption, energy consumption, and biomass price as parameters, to evaluate their impressions on the economic cost, subject to an increase or
decrease by 20% (Fig. 2).
The cost of algae-derived biofuel is most sensitive to the biomass price. The
rising selling prices of biomass will greatly increase the profits of products and
byproducts, ultimately lowering the actual economic cost. A 50.15% rise in the cost
has been estimated, following a 20% increase in the biomass selling price. Thus,
improving cultivation technology and promoting microalgae recovery efficiencies,
oil extraction, and conversion rate, are a few effective approaches to enhance the
economic performance.
In addition, the impacts of PBR cost, and operating period of the system on
actual economic cost are significant. PBR is one of the principal project devices and
incurs high expenses as well. It is anticipated that the breakthrough in the procurement of equipment, as a result of scientific and technological progress, will
eventually reduce the cost of equipment input. Moreover, operation time constitutes
a significant factor, having substantial connections with investments including the
rental price of the land, energy, chemical and nutrient consumption, and wastewater
cycling rate. A *14% increase in the tangible cost is probable, provided the
operation time is cut down by 20%.
164
K. Peng et al.