Alternatives to fossil fuels such as biofuels have shown promise in not only reducing harmful gaseous emissions, but in facilitating the return of the Earth’s atmosphere to equilibrium (Gouveia and Cristina, 2009). Although oleaginous crops are normally used to produce biofuels, recent research has concluded that microalgae can be 10–20 times more efficient than oleaginous seeds or vegetable oils. In addition, microalgae fix carbon dioxide and thus help to decrease greenhouse gases in the atmosphere. After oil is extracted from the algae, the remaining product can be further processed to create fertilizer, feed, biogas, or high value chemical compounds.— Alec Faggen
Gouveia, L., Oliveira, A., 2009. Microalgae as a raw material for biofuels production. Journal of Industrial Microbiology & Biotechnology 36, 269-274.
Gouveia and Cristina at the Instituto Nacional de Engenharia compared six species of microalgae to determine the algae with the fastest growth rate and highest oil content with adequate composition. Nannochloropsis sp. and Neochloris oleabundans have high oil contents and under nitrogen depletion, increase oil quantity by about 50%. The oil content is characterized by iodine value. Careful comparisons of these values demonstrate that these microalgae have better quality oil than some vegetable oils. Although neither Nannochloropsis sp. nor Neochloris oleabundans alone can produce biodiesel, when used in conjunction with other microalgal oils and/or vegetable oils, they are viable. Although its oil quantity is smaller, Scenesdesmus obliquus has the best fatty acid profile and is feasible without other algae or oils.
Microalgae are especially promising sources for biofuel due to their fast growth rate, their high photosynthetic efficiency, their high biomass productivities, their ability to be harvested daily, their minimal need for water, and their capacity to grow in infertile land. However, cell lipid content must be monitored during production, which, in addition to being time consuming, produces harmful wastes if not properly distilled. Advances in biorefinery and photobioreactor engineering will help to resolve these limitations. As the biodiesel market speedily expands, microalgae is arguably the only potential source of renewable biodiesel that does not disrupt food production.—Alec Faggen