Scientists from the University of Texas at El Paso demonstrated a new technique to improve the yield of biofuel from microalgae. Their study in ACS Applied Bio Materials centers on the microalga Chlorella vulgaris, which is commonly found in freshwater and can be used to produce biofuels.
The team, led by Hamidreza Sharifan, Ph.D., assistant professor in the Department of Chemistry and Biochemistry (left), includes Luis Salmeron Covarrubias, a senior environmental science major (center), and Kavitha Beluri, a doctoral student in environmental science and engineering. Credit: The University of Texas at El Paso
The researchers demonstrated that doses of zinc oxide (ZnO) nanoparticles can enhance the lipid content of the microalga, including triacylglycerol, which is utilized in the production of biofuels.
When the researchers exposed the C. vulgaris cells to 30-50 mg/L of synthesized ZnO, the cells’ lipid content increased from 14% to 48%, more than a 300% increase. They found that concentrations of ZnO above 50 mg/L caused oxidative damage to the cells, while concentrations below 30 mg/L did not optimize lipid production.
The team is continuing to refine this process and hopes to show its reliability at a large scale as well as with other microalgae species.
The biofuel suitability score
The researchers also developed the Biofuel Sustainability Score (BSS), which combines multiple factors to evaluate and optimize the conditions of biofuel production. The BSS framework could provide insights for future strategies in biofuel production.
The BSS integrates lipid content, biomass productivity, oxidative stress levels and pigment retention to determine the best conditions for biofuel production. The researchers designed the framework to determine the best balance between oxidative stress management and lipid production.
The BSS is a weighted percentage of lipid percentage, biomass productivity, photosynthetic pigments and oxidative stress, where stress lowered the BSS while the other parameters increased the score.
The researchers used their BSS formula to determine that their method worked best at concentrations between 30-50 mg/L, optimizing lipid production without sacrificing cell health.
Using microalgae for biofuel
Algae biofuel is an alternative to fossil fuels that uses algae to produce oils. Lipids from the algae are extracted and converted into biodiesel or refined into replacements for petroleum fuels. The carbohydrate content of algae can be fermented into bioethanol or butanol fuel.
Some research has shown that algae species are made up of 40% lipids by weight, according to Britannica, all of which can be turned into biofuel. The process is also carbon neutral, as algae take in carbon dioxide during photosynthesis, offsetting the CO2 that is released when the fuel is burned. Compared to other biofuel resources, such as corn, algae can produce more oil per acre, making it a more efficient option for biofuel production.
