It turns out that all that green guck that built up in your aquarium was capable of doing more than you ever thought: Generating fuels that can potentially replace fossil fuels in the distant future.
Human factors (anthropogenic activities) such as burning fossil fuels are increasing the concentrations of CO2 into the atmosphere, causing a climate warming (global warming).
In an attempt to decrease the amount of atmospheric CO2, algae are considered an alternative solution. Algae are microorganisms that are capable of harnessing solar energy, nutrients, and CO2 to produce compounds for their own survival (i.e. carbohydrates, fats, proteins, pigments). Some species of microalgae may also grow in the absence of light, while different species require either inorganic (CO2) or organic carbon sources for their own metabolisms. Algae can use (or fix) and ‘eliminate’ CO2 at rates that are 10 – 50 times more efficient than plants (which are expected to reduce only 3 – 6% of global CO2 emissions).
Most importantly, with a little human intervention, algae can generate biofuels, an alternative energy source that may rival the fossil fuels we currently use to rev our vehicles and heat our various infrastructures. Unlike plants (which can also produce biofuels), algae have high growth rates, can tolerate high water temperatures, and are also simple to harvest. One study even estimates that certain algae species (belonging to the organismal families Chlorella, haematococcus, and punaliella) can produce more biofuels than certain crops (soya and Jatropha species), and even require significantly less land area for their production!
Specifically, algae are capable of producing biodiesel, a type of biofuel that is produced by chemically reacting fats (called lipids) with an alcohol (a compound that contains –OH—known as hydroxyl—in their chemical structure).
Biodiesel production through algae initially requires the organisms to produce lipids, molecules that are essential for maintaining their cellular activities. Many (but not all) lipids cannot dissolve in water, and typically contain hydrogen and carbon in their structure. Algal species can produce triacylglyercides (TGs)—a type of lipid—that are important constituents for biofuel production. The lipids are thereby combined with alcohols via transesterfication reaction, to produce the biodiesel and glycerol (another byproduct that is not used for biodiesel production).
Large-scale production of biodiesel via algae does face potential challenges. It can be cost-effective and involve easy maintenance if open ponds are used to grow the algae. However, it is challenging (if not impossible) to control the environmental conditions surrounding the pond, which influences the algal growth rate and its ultimate generation of biodiesels. Environmental factors such as nutrient abundance, amount of available sunlight, water acidity, and the concentration of dissolved salts in the water can greatly influence algae metabolism. Contamination (or invasion of other organisms) may also occur, which can further affect biodiesel production. In contrast, growing algae in bioreactors can be easier to control these environmental conditions and contamination events, but are more costly.
Nonetheless, algae are also capable of producing other biofuels through similar cellular activities, such as bioethanol, biogas, biosyngas, and biohydrogen. Although these alternatives source to energy does present their own limitations and challenges, their utilization to the global society is a work in progress.
Scientific Journal Articles
- Didem Özçimen, M. Ömer Gülyurt and Benan İnan (2012). Algal Biorefinery for Biodiesel Production, Biodiesel – Feedstocks, Production and Applications, Prof. Zhen Fang (Ed.), ISBN: 978-953-51-0910-5, InTech, DOI: 10.5772/52679. Available from: http://www.intechopen.com/books/biodiesel-feedstocks-production-and-applications/algae-as-natural-biorefinery
- Hannon, M., Gimpel, J., Tran, M., Rasala, B., and Mayfield, S. (2010). Biofuels from algae: Challenges and potential. Biofuels, 1(5), 763-84.
Renee C. has received her B.Sc. in Honours Life Sciences at McMaster University. She loves educating others about different topics in science, and has developed a passion for scientific outreach. When she’s not writing articles for Hemtecks, she’s either volunteering or checking her social media accounts every 20 minutes. Along with Tiffany (Tianhemtecks), she also facilitates the blog’s Facebook page.