Comparative scoping study report for the extraction of microalgae oils from two subspecies of Chlorella vulgaris

Abstract

The production of microalgae as a fatty acid oil resource for use in biofuels production is a widespread research topic at the lab scale. Microalgae contain a higher lipid content on a dry-weight basis compared to oilseeds such as soybeans. Additionally, the growth and cultivation cycle of microalgae is 15 days, in comparison to soybeans, for which the cycle occurs once or twice annually. However, to date, it has been uneconomical to produce microalgae oils in a world-scale facility due to limitations in cultivating microalgae at commercial scales. Recent developments suggest that the use of heterotrophic microalgae may be economically feasible for large-scale oil production. To assess this feasibility, a comparative scoping study was performed analysing the feasibility of an industrial-scale process plant for the growth and extraction of oil from microalgae. Processes were developed at the preliminary design level using heterotrophic subspecies and autotrophic subspecies of Chlorella vulgaris. AACE Class 4 cost estimates and economic analyses were performed. This study concludes that processes based on heterotrophic microalgae are more likely to reach economic feasibility than processes using autotrophic microalgae. However, a few barriers still remain to achieving free-market economic viability.

Microalgae-Based PUFAs for Food and Feed: Current Applications, Future Possibilities, and Constraints

“…The main reasons behind the high production costs are related to the low yields of PUFAs within microalgal biomass [80], which may depend on the cell growth and on the extraction methods. Novel growth strategies aimed at achieving economic viability of mass culturing foresee the employment of waste carbon sources in heterotrophically growing cultures [81] in order to recycle and minimize reject goods, as well as the improvement of harvesting and dewatering technologies, which account for up to 20-30% of the whole biomass cost [71,[82][83][84]. However, the high costs related to artificial illumination and energy requirements of air and/or gas sparging inside photobioreactors actually make their use economically unsustainable; thus, open ponds rather than enclosed chambers are more feasible as cultivation systems.…”