Algae Biofuel: Potential, Challenges, and Innovations

By Dr. Priyom Bose, Ph.D.Reviewed by Laura ThomsonJul 9 2024

Algae are a diverse group of photosynthetic organisms in marine and freshwater.¹ Considering the global fossil fuel crisis, in 1978, the US Department of Energy’s Office of Fuels Development funded a program called the Aquatic Species Program (ASP), which focused on the production of biofuel from algae.² Ever since, many scientists worldwide have assessed the potential of algae as a major biofuel producer.

Image Credit: Toa55/Shutterstock.com

Why Algae are a Potential Candidate for Biofuel Production

Algal species, particularly marine microalgae, are responsible for fixing more than 40% of global carbon.³

Two primary features that make algae a potential biofuel producer are rapid growth that leads to high biomass production and the ability to synthesize energy-rich oils. For example, 50% of Botryococcus spp dry mass contains long-chain hydrocarbons.⁴

Microalgae, including diatoms, green algae, eustigmatophytes, golden brown, and prymnesiophytes, are mostly investigated as potential biofuel candidates.⁵ The major advantage of using single-celled microalgae is the ease of applying high-throughput technologies to rapidly evolve strains. 

Compared to terrestrial crop plants, algae are a better source of biomass for biofuels due to their capacity to remediate wastes from streams or municipal wastewater. Bioengineered algal strains also produce valuable co-products, such as eicosapentaenoic acid, arachidonic acid, and γ-linoleic acid, which enable them to compete economically with petroleum.⁶

Another minor microalgae commercial product is phycobiliproteins used in food and cosmetics. 

Many studies have underscored the commercial importance of microalgae through their production of lectins, toxins, antibiotics, vitamins, sterols, halogenated compounds, mycosporine-like amino acids, and polyketides.⁷

Factors and Strategies to Make Algae Biofuels Viable

Thousands of algal species have been collected and evaluated in algal biofuel production. Scientists manipulated the genes and metabolisms to substantially increase algal biofuel production.

An improvement in photobioreactor (PBR) design is required to facilitate better nutrient circulation and light exposure. This would positively impact algae biofuel production. Engineers must also focus on creating cost-effective PBRs for large-scale deployment. A collaboration between engineers and biologists could result in the development of low-cost open systems.⁴

Oil is extracted from algae through three different methods, namely, supercritical CO₂ fluid extraction, oil press/expeller, and hexane extraction.⁸

Although all three methodologies are efficient, they require relatively expensive equipment or energy. Engineers focus on tweaking the methodology or equipment to reduce manufacturing costs.

Both crude algae oil and fossil fuel oil are chemically similar. Bioengineers are currently addressing the issue of effectively converting algae oil to usable liquid fuels. An efficient catalyst would enable gasoline production from bio-oil.⁹

A significantly large plant dedicated to algae production is essential to completely replacing fossil fuels with algal biofuel. According to a recent estimation, approximately 30 million acres of land will be required to develop terrestrial aquaculture to fulfill only the US oil demand. Typically, terrestrial aquaculture uses lands not utilized for food agriculture and has minimum economic utility.

The amount of water, sunlight, and nutrients required for growth must be considered for algal mass culture.

Water is vital for algal growth, while iron is a significant limiting factor in the ocean. Sulfur deficiency markedly decreases algal biomass by hindering growth.⁴ Therefore, for optimal algal growth, it is important to consider various factors, including micro- and macro-nutrients, water, and sunlight exposure.

Large algal monocultures often become infected with pests and pathogens. Crop protection is another aspect for phycologists to manage to ensure proper maintenance of algal pond sustainability.¹⁰ Pathogen-resistant algal strains with robust growth characteristics and significant lipid composition must be cultivated for algal biofuel production.

Algae Biofuel Commercialization: Rise and Fall

After decades of research since 1978, ASP failed to develop industry-standard algal biofuel. A primary reason for this commercial failure was the high cost associated with algal maintenance compared to the relatively low price of fossil fuels. 

Although this failure momentarily diverted scientists’ attention from algal biofuel production, the sharp rise in oil prices at the beginning of the 21^st century compelled them to reassess microalgae's potential as a biofuel producer.

A recent study has indicated that biodiesel from microalgae produces more carbon emissions than petroleum-based diesel.¹¹ The biofuel manufacturing process using algae requires more energy than the final product can produce. 

ExxonMobil is an American multinational oil and gas corporation that recently withdrew from algal biofuel research. The company invested almost 14 years in cultivating algae as a profitable feedstock for biofuel.  

Even after ExxonMobil withdrew from its initial plan of developing algal biofuel that could be used as a liquid alternative energy source to power ships, aviation, and long-distance trucking, many researchers continue to believe in the potential of microalgae as a source for alternative fuel, with some tweaks. 

To commercialize algae biofuel, it is essential to develop a less energy-intensive method, such as growing phytoplankton outdoors under natural light. 

California-based algae biofuel company Viridos has also gained newer investors, such as United Airlines and Chevron, to continue research on the commercialization of microalgal biofuel.

The company aims to develop sustainable aviation fuel (SAF) and renewable diesel fuel (RD) using genetically modified oil-rich algae. The use of SAF and RD could reduce 70% carbon footprint.

In conclusion, algae's journey as a potential biofuel source has been marked by significant advancements and notable setbacks.

Despite the initial promise demonstrated by the Aquatic Species Program and the continuous efforts of scientists worldwide, the commercialization of algal biofuels has faced substantial challenges, primarily due to high production costs and energy inefficiencies. However, the potential of algae remains undeniable, particularly with ongoing innovations aimed at reducing costs and improving efficiency.

As global interest in sustainable and renewable energy sources grows, the collaborative efforts of engineers, biologists, and commercial entities like Viridos offer hope for a future where algae can play a crucial role in meeting our energy needs while reducing the carbon footprint.

With sustained research and development, algae may become a viable alternative to fossil fuels, contributing to a more sustainable and eco-friendly energy landscape.

References and Further Reading

1. Raven JA, Giordano M. Algae. Current Biology. 2014; 24(13), R590-R595. https://doi.org/10.1016/j.cub.2014.05.039
2. Maliha A, Abu-Hijleh B. A review on the current status and post-pandemic prospects of third-generation biofuels. Energy Syst. 2023; 14, 1185–1216. https://doi.org/10.1007/s12667-022-00514-7
3. Zabochnicka M, Krzywonos M, Romanowska-Duda Z, Szufa S, Darkalt A, Mubashar M. Algal Biomass Utilization toward Circular Economy. Life (Basel). 2022;12(10):1480. https://doi.org/10.3390/life12101480
4. Hannon M, Gimpel J, Tran M, Rasala B, Mayfield S. Biofuels from algae: challenges and potential. Biofuels. 2010;1(5):763-784. https://doi.org/10.4155/bfs.10.44
5. Radakovits R, Jinkerson RE, Darzins A, Posewitz MC. Genetic engineering of algae for enhanced biofuel production. Eukaryot Cell. 2010;9(4):486-501. https://doi.org/10.1128/EC.00364-09
6. Khoo KS, et al. Enhanced microalgal lipid production for biofuel using different strategies including genetic modification of microalgae: A review. Prog Energ Combust Sci. 2023; 96, 101071. https://doi.org/10.1016/j.pecs.2023.101071
7. Tounsi L, Ben Hlima H, Hentati F, Hentati O, Derbel H, Michaud P, Abdelkafi S. Microalgae: A Promising Source of Bioactive Phycobiliproteins. Marine Drugs. 2023; 21(8):440. https://doi.org/10.3390/md21080440
8. Ranjith Kumar, R. Lipid Extraction Methods from Microalgae: A Comprehensive Review. Front Energy Res. 2015; 2, 125610. https://doi.org/10.3389/fenrg.2014.00061
9. Guvenc, C. et al. Catalytic upgrading of bio-oil model mixtures in the presence of microporous HZSM-5 and γ-Al2O3 based Ni, Ta and Zr catalysts. Fuel, 2023; 350, 128870. https://doi.org/10.1016/j.fuel.2023.128870
10. Abd-Elmaksoud S, Abdo SM, Gad M, Hu A, El-Liethy MA, Rizk N, Marouf MA, Hamza IA, Doma HS. Pathogens Removal in a Sustainable and Economic High-Rate Algal Pond Wastewater Treatment System. Sustainability. 2021; 13(23):13232. https://doi.org/10.3390/su132313232
11. Bradley, T., Rajaeifar, M.A., Kenny, A. et al. Life cycle assessment of microalgae-derived biodiesel. Int J Life Cycle Assess 28, 590–609 (2023). https://doi.org/10.1007/s11367-023-02140-6

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