Algae Biofuel: Can Pond Scum Power the Planet?

Krysta Levac
Readability
8.3

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Learn about the potential of algae as a material for making biofuel.

Algae could be a lean, mean biodiesel machine. Or maybe not so lean. Algae’s oil is what makes it a great potential feedstock for biofuel. Feedstock is a material used to make biofuel. Biodiesel is an important type of biofuel

Biodiesel can be used instead of petroleum-based diesel fuel. It can also be blended with it. Biodiesel made from algae oil is called a Third Generation biofuel. For now, only a few refineries are making it. But it could become a major source of biofuel one day. 

Algae 101

Algae belong to a group of non-plant photosynthetic organisms. They make sugar and oxygen using water, carbon dioxide (CO2) and energy from the Sun. Some algae, like seaweed, are large and multicellular. But many are microscopic and single-celled, like the green microalgae used for biodiesel production. The cells in green algae metabolize the sugar they produce into oil. This is a way to store energy. 

Various types of algae
Various types of algae including A: Blue green algae on a river (Source: CSIRO [CC BY] via Wikimedia Commons); B: Red algae on bleached coral (Source: Johnmartindavies [CC BY-SA] via Wikimedia Commons); C: Microalgae (Source: CSIRO [CC BY] via Wikimedia Commons); and D: Brown and green algae in the ocean (Source: Ansgar Gruber [CC BY-SA] via Wikimedia Commons).

Did you know? 

Green algae can grow very quickly. Some species accumulate oil until the oil is more than half their mass! 

How biodiesel is made from algae

Plant and animal fats, including the oil in algae, have long organic molecules called triglycerides

Example of a triglyceride
Example of a triglyceride (C55H98O6). It is made up of glycerol, palmitic acid, oleic acid and alpha-linolenic acid (Source: Wolfgang Schaefer [public domain] via Wikimedia Commons).

 

The first step in making biodiesel is to extract the oil containing the triglycerides from the algae. There are two ways to do this. One is by mechanically pressing the algae, like you would press olives to make olive oil. The other way is by combining the algae with an organic solvent

Then, the triglycerides are converted into fatty acid methyl esters (FAMEs). This happens through a transesterification reaction. This same process can be used to derive FAMEs from canola oil or waste cooking grease. 

Triglycerides react with methanol to form fatty acid methyl esters and glycerin
Triglycerides react with methanol to form fatty acid methyl esters and glycerin (©2020 Let’s Talk Science).

 

Infographic showing the main steps in producing biodiesel from algae
Infographic showing the main steps in producing biodiesel from algae (©2020 Let’s Talk Science). 
Graphic - Text version

The steps in making biodiesel from algae include growing the algae, harvesting the algae, extracting oil from the algae and transesterification.

 

Miniature Science #2: Growing Algae For Biofuels (2019) by ExxonMobil (1:18)

Like biodiesel feedstock crops like canola, algae can be farmed. Farmed algae have the same requirements as the green algae that grow in ponds, swimming pools, and aquariums. They need water, sunlight, CO2 and nutrients like nitrogen and phosphorus to grow. 

There are two main ways to farm algae:

Outdoor open ponds look like big pools. They have moving water which circulates the algae. This way, all the algae get the same amount of exposure to sunlight. 

A design for outdoor algae pools
A design for outdoor algae pools. This style is known as a raceway pond (Source: Ivan Castilho [CC BY-SA] via Wikimedia Commons).

 

There are some disadvantages to using open pools. The water can evaporate quickly because they have large surface areas. They’re also at risk of getting contaminated by other algal species.

Closed bioreactors are closed, indoor environments where algae can grow. They come in a variety of shapes and styles. The advantage of these is that humans can carefully control the growing conditions. But they are much more expensive to build and maintain than open ponds.

Algae growing in a bioreactor
Algae growing in a bioreactor (Source: IGV Biotech [CC BY-SA] via Wikimedia Commons).

What are some benefits of using algae to produce biodiesel?

There are a few benefits to using algae feedstock for biodiesel production, instead of crop feedstock like canola. They are:

  1. Algae contain more oil in a smaller area than some other crops. Scientists aren’t sure how much more oil. But it could be two to ten times more.
  2. Algae do not need farmland. This means that they do not compete with crops for high-quality agricultural land.
  3. Algae could help improve air pollution. Algae need large amounts of CO2 to support photosynthesis. Some of this CO2 could come from things like industrial emissions. 
  4. Algae need water, but it doesn’t have to be clean water. research project run by NASA has shown that algae can grow in municipal wastewater in floating plastic bioreactor tubes. As the algae grows, it cleans the wastewater by extracting nutrients. The algae can then be used for biofuel production. 
Infographic showing some of the advantages of growing algae, rather than canola, as a biofuel feedstock
Infographic showing some of the advantages of growing algae, rather than canola, as a biofuel feedstock (©2020 Let’s Talk Science). 

Did you know? 

The Canadian Research Council has partnered with two companies, Pond Tech and St. Mary’s Cement, to build an algal biorefinery. The goal is for Pond Tech to use the waste products from St. Mary’s Cement to grow algae. In turn, that algae can produce biofuels!

What are some downsides of using algae to produce biodiesel?

There have also been concerns about the sustainability of algae biofuels. The main concerns are:

  1. Growing algae in ponds takes a lot of water. Water evaporates from the pond surface. That means that more water needs to be added all the time. This is less of an issue in biorefineries because they are closed systems.
  2. Bioreactors need a lot of energy to grow algae. The energy is used to circulate water, provide light and maintain the best temperature. This is less of an issue in outdoor ponds because light and thermal energy comes from the Sun. But energy is still needed in outdoor ponds to circulate water.
  3. Biorefining is a slow process. Algae grow fast, but extracting and refining the oil they produce is slow. It is slower than other methods of producing biofuels. 
  4. Algal biofuels may have a negative energy balance. In other words, algal biofuels may take more energy to produce than they provide!
  5. Algal biofuel facilities are very expensive to build and operate. This means that algal biofuels may end up costing more than most people or businesses are willing to pay.

But some of the benefits of algal biofuel could help with these drawbacks. Things like capturing CO2 from industrial waste and using nutrient-rich wastewater may help unlock algae’s full biofuel potential. 

Algae Biofuels beyond Biodiesel

There are other ways to harness energy from algae. For example, algae can be dried into ‘algae coal’ and burned with fossil coal in power plants. Algae can also be used to generate biogas. This technology uses bacteria to break down organic material like algae in anaerobic (no-oxygen) conditions. The bacteria produce methane biogas, which can be burned to generate electricity. 

Algae biofuels are not common yet. But if scientists can find a way to unlock their energy at a lower cost, the future looks green. And maybe a little slimy!

 

Starting Points

Connecting and Relating

  • Where have you seen algae growing before? What do you think of when you see it growing? 
  • When you hear the term aquaculture, what comes to mind? 
  • Have you or someone you know driven a diesel car before? What features of a diesel car do you like or dislike?

Connecting and Relating

  • Where have you seen algae growing before? What do you think of when you see it growing? 
  • When you hear the term aquaculture, what comes to mind? 
  • Have you or someone you know driven a diesel car before? What features of a diesel car do you like or dislike?

Relating Science and Technology to Society and the Environment

  • How does the environmental impact of biodiesel from algae differ from that of a field crop source of biodiesel, like canola?
  • What are the environmental concerns related to scaling up algal biofuel production? 

Relating Science and Technology to Society and the Environment

  • How does the environmental impact of biodiesel from algae differ from that of a field crop source of biodiesel, like canola?
  • What are the environmental concerns related to scaling up algal biofuel production? 

Exploring Concepts

  • What is the chemical process that is required to make biodiesel? 
  • How is algae cultivated for biodiesel production? 
  • What is the function of a bioreactor? 
  • Besides biodiesel, what other form of energy could be possible from algae?

Exploring Concepts

  • What is the chemical process that is required to make biodiesel? 
  • How is algae cultivated for biodiesel production? 
  • What is the function of a bioreactor? 
  • Besides biodiesel, what other form of energy could be possible from algae?

Nature of Science/Nature of Technology

  • How is the development of an algae biofuel industry connected to innovations in technology?

Nature of Science/Nature of Technology

  • How is the development of an algae biofuel industry connected to innovations in technology?

Media Literacy

  • If you were an algae biofuel manufacturer, how would you market it? Create a storyboard for a commercial that promotes the features, advantages and benefits of algae biofuel. 

Media Literacy

  • If you were an algae biofuel manufacturer, how would you market it? Create a storyboard for a commercial that promotes the features, advantages and benefits of algae biofuel. 

Teaching Suggestions

  • This article can be used to support teaching and learning of Biology, Biotechnology, Chemistry and Alternative Energy related to biofuels, industrial biotech and aquaculture. Concepts introduced include feedstock, solvents, bioreactors and biogas. 
  • After reading this article, teachers could have students complete a Concept Definition Web learning strategy for the concept of algal biodiesel. Ready-to-Use Concept Definition Web reproducibles for this article are available in [Google doc] and [PDF] formats. 
  • To consolidate learning from this article, teachers could have students use a Pros & Cons Organizer learning strategy to consider the positive and negative aspects of algae biofuel production and use. Ready-to-Use Pros & Cons Organizer reproducibles for this article are available in [Google doc] and [PDF] formats. 

Teaching Suggestions

  • This article can be used to support teaching and learning of Biology, Biotechnology, Chemistry and Alternative Energy related to biofuels, industrial biotech and aquaculture. Concepts introduced include feedstock, solvents, bioreactors and biogas. 
  • After reading this article, teachers could have students complete a Concept Definition Web learning strategy for the concept of algal biodiesel. Ready-to-Use Concept Definition Web reproducibles for this article are available in [Google doc] and [PDF] formats. 
  • To consolidate learning from this article, teachers could have students use a Pros & Cons Organizer learning strategy to consider the positive and negative aspects of algae biofuel production and use. Ready-to-Use Pros & Cons Organizer reproducibles for this article are available in [Google doc] and [PDF] formats. 

Learn more

Energy 101 | Algae-to-Fuels (2012)

This video (2:33 min.) by the US Department of Energy outlines how algae can be used to produce biofuel as well as how algae farms may be the next step in producing a reliable fuel source.

Energy from floating algae pods (2012)

In this TED Talk video (14:45 min.), NASA scientist Jonathan Trent, explains the OMEGA system, which uses microalgae to convert wastewater into clean water and usable fuel.

Turning algae into fuel (2012)

In this video (2:45 min.) scientists in the chemical engineering department at the University of Michigan talk about their work on developing algae as a biofuel.

References

Ayers, C. (2019, February 19). 15 advantages and disadvantages of using algae as a biofuel. Green Garage.

Bailey, R. (2019, May 8). All about photosynthetic organisms. ThoughtCo.

Cassidy, S. (2010, December 27). How can algae be converted into biofuel? How Stuff Works.

Lombardo, C. (n.d.). 7 advantages and disadvantages of algae biofuel. Future of Working.

Murphy, J. D., Drosg, B., Allen, E., Jerney, J., Xia, A., and Herrmann, C. (2015). A perspective on algal biogas. IEA Bioenergy.

Penn State College of Earth and Mineral Sciences. (2018). 9.2 The reaction of biodiesel: Transesterification.

Smith, A. M., & Ross, A. B. (2016). Production of bio-coal, bio-methane and fertilizer from seaweed via hydrothermal carbonisation, Algal Research, 16, 1-11. DOI: 10.1016/j.algal.2016.02.026

U.S. Office of Energy Efficiency & Renewable Energy. Algal biofuels.

Wood, R. (2012, April 22). Algae biofuels: Feasibility analysis and policy recommendations. McMaster University.