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A biodiesel filling station

A biodiesel filling station (JosefLehmkuhl, Wikimedia Commons)

STEM in Context

Biofuels: An Alternative Energy Source

Damitha Gunathilake & Let's talk Science

Summary

Biofuels are a renewable energy resource that can often substitute for fossil fuels. Why are biofuels promising, and why aren’t we using more of them?

Have you ever switched on a light? Have you ever used a laptop or a smartphone? Have you ever ridden in a car or a bus? If you answered “yes” to any of these questions, you have used energy. As technology develops and the world’s population grows, people need more and more energy. But meeting this need sustainably can be a challenge!

Since the Industrial Revolution, most of the energy we use comes from burning fossil fuels. According to the International Energy Agency (IEA), the amount of global energy produced by burning fossil fuels has been fairly steady over the past 30 years. As of 2015, approximately 80% of the world’s energy comes from burning fossil fuels.

But scientists are getting more and more interested in renewable energy sources, such as biofuels. Let’s look at why.

Did you know? 

Biofuel accounts for approximately 9% of the total amount of global energy used.

Fossil fuels versus biofuels: what’s the difference? 

Fossil fuels are solid, liquid or gaseous forms of hydrocarbons. These are -- you guessed it! -- compounds made of hydrogen and carbon. Fossil fuels come from biological materials that have been dead for a very long time. For example, they might come from plant and animal materials that were buried under many layers of mud, rock, and sand millions of years ago. Over time, the heat from inside the Earth and the pressure of these layers turned the dead material into fossil fuels. 

Biofuel pump at a gas station
Biofuel pump at a gas station (Source: RCB via pxhere).

Did you know? 

The concept of using biofuels has been around since the 1800s! Henry Ford believed that ethanol would be the fuel of the future. 

What is Biofuel and How is it Used? 

Biofuels are derived from recently dead or living plant material and animal waste. This differs from fossil fuels, which are derived from long-dead plant and animal matter. The most commonly used biofuels are ethanol and biodiesel. They are produced from plants that are usually grown as crops. These plants make up the biomass that’s used as the feedstock in biofuel production. Feedstock is any material that is used to make biofuels. In North America, corn is the main type of feedstock used in ethanol production. 

To produce ethanol from corn, the first step is to break down starch. Starch is a complex carbohydrate. To produce ethanol, it must be broken down into simple sugars like dextrose and glucose. A process called fermentation then converts these sugars to ethanol.

Corn field in Ontario
Corn field in Ontario (Source: Illustratedjc [CC BY-SA 3.0]via Wikimedia Commons).

Did you know?

Yeast ferments sugar into ethanol in anaerobic conditions. This means that the process can occur without oxygen!

Biodiesel is made from vegetable oils or animal fats. A reaction called transesterification is responsible for the conversion of plant oils to biodiesel. Transesterification is the reaction of an alcohol with oil or fat to produce fatty acid alkyl esters, otherwise known as biodiesel.

Canadian biorefineries have the capacity to produce 1.7 billion litres of ethanol per year. Most of this is mixed into gasoline. The majority of gasoline-powered vehicles built since the 1980s can run on a mixture of up to 10% ethanol (E10) without any engine modifications. Some North American car companies make Flexible Fuel, or Flex-Fuel, vehicles with modified engines. These engines can use mixtures of up to 85% ethanol and 15% gasoline (E85). 

Did you know?

The United States and Brazil are the world leaders in biofuel production. Together, they produce 70% of the world’s biofuels!

Canada’s Renewable Fuel Regulations were enacted in 2010. They require that non-renewable fossil fuel contain an average of 5% renewable fuel content. That 5% level is currently being met with corn and wheat ethanol (E5). What about the E85 blend that can be used in Flex-Fuel vehicles? Some Canadian companies with large fleets of vehicles use E85. But it is not yet widely available. There are only a handful of gas stations in Canada that sell E85. In contrast, there are over 3 000 gas stations with E85 pumps in the U.S. That may sound like a lot. But it is still less than 2% of total fuel stations. 

Why use biofuels instead of fossil fuels? 

Fossil fuels are a non-renewable resource. Eventually, if we keep using them, they will run out. Some energy sources, such as the Sun and wind, are considered sustainable because they are renewable. Biofuels are renewable, too. In other words, you can grow biomass feedstock again and again to continuously produce biofuels.

Not only are fossil fuels non-renewable, they’re also bad for the environment. Burning fossil fuels releases an enormous amount of greenhouse gases, such as carbon dioxide (CO2), into the atmosphere. This contributes to global warming. Ethanol  produces CO2 when it’s burned. However, it is considered carbon neutral. This is because the biomass feedstock that is used to make ethanol absorbs CO2 as it grows. That means the burning of biofuels does not increase greenhouse gas levels. 

You can substitute biofuels for fossil fuels in many ways. That’s why researchers are so interested in them!

What are biofuels made of?

Scientists divide biofuels into four categories or “generations,” depending on the raw materials used to produce them. First-generation biofuels are made mainly from food-related sources. Examples include starch from cereal plants like corn and wheat, sugar from sugarcane, vegetable oils and animal fats. Fuel can be made from these substances in many ways, including through the help of microorganisms (bacteria and other tiny organisms). For example, a fungus called Saccharomyces cerevisiae (yeast) can ferment sugar into ethanol.

Second-generation biofuels are produced from non-food sources. They are mainly made from the cellulose that make up cell walls. That’s why they’re also called cellulosic biofuels. Wood and straw are examples of materials used to produce cellulosic biofuels. So are crop residues. Those are the materials left over after the edible part of a crop is harvested.

Third-generation biofuels are produced by certain species of algae. That’s why they’re also called algal fuels. Some algal species can secrete oily substances. These substances can be used as biofuels. Algae photosynthesize, and therefore create their own energy. That’s why they are seen as a low-cost, high-energy source for making biofuels. However, large-scale algal biofuels are still very expensive to produce. Researchers are trying to develop better harvesting techniques and bioreactors. Bioreactors are a type of instrument used to grow microorganisms.

Fourth-generation biofuels make up the newest sector of biofuel technology, in which scientists are trying to find a source of bioenergy that doubles as a method for capturing and storing CO2. These biofuels are usually created through advanced biochemistry techniques or petroleum-like hydroprocessing

Summary of the four generations of biofuels
Summary of the four generations of biofuels (©2019 Let’s Talk Science).

 

Infographic - Text Version

Let's review. First-generation biofuels come from food-related sources, like starch from corn and wheat. Second-generation biofuels come from non-food sources like cellulose. Third-generation biofuels come from algae. Fourth-generation biofuels come from other sources.

 

What is the future of biofuels?

So why isn’t everyone using biofuels? Just like with other fuels, there are some challenges involved with producing biofuels. These include the cost of production and the source of the feedstock. Maybe one day, new technologies can make biofuel production cheaper. And researchers will find ways to use feedstocks not otherwise used for food. If these things happen, biofuels might soon become one of the best substitutes for fossil fuels!

Starting Points

Connecting and Relating
  • Have you or anyone you’ve driven with ever filled up the car with ethanol? Why or why not?
  • Can you purchase E85 fuel at your local gas station? How often do you see vehicles filling up with ethanol fuel?
Connecting and Relating
  • Have you or anyone you’ve driven with ever filled up the car with ethanol? Why or why not?
  • Can you purchase E85 fuel at your local gas station? How often do you see vehicles filling up with ethanol fuel?
Relating Science and Technology to Society and the Environment
  • Is it worthwhile for people to invest in cars that can use ethanol fuel? Explain.
  • How does the availability of an ethanol fuel option (e.g., E85) at the pump impact the sales and purchases of ethanol option vehicles? 
Relating Science and Technology to Society and the Environment
  • Is it worthwhile for people to invest in cars that can use ethanol fuel? Explain.
  • How does the availability of an ethanol fuel option (e.g., E85) at the pump impact the sales and purchases of ethanol option vehicles? 
Exploring Concepts
  • What are the differences between fossil fuels and biofuels?
  • What are the key differences between the four generations of biofuels? 
  • Conduct research to explore what types of wastes are being used to make second-generation or cellulosic biofuels.
Exploring Concepts
  • What are the differences between fossil fuels and biofuels?
  • What are the key differences between the four generations of biofuels? 
  • Conduct research to explore what types of wastes are being used to make second-generation or cellulosic biofuels.
Nature of Science/Nature of Technology
  • Using the example of third-generation biofuels, how do interactions between the science and technology impact on the progress of developing a biofuels product that can be used in the general marketplace?
Nature of Science/Nature of Technology
  • Using the example of third-generation biofuels, how do interactions between the science and technology impact on the progress of developing a biofuels product that can be used in the general marketplace?
Media Literacy
  • Companies like Exxon have been doing promotional advertising about third-generation algal biofuels in recent years. Why would a company that manufactures and sells traditional fossil fuels be promoting an alternative biofuel? Are there other fuel companies that are doing similar promotional advertising? 
Media Literacy
  • Companies like Exxon have been doing promotional advertising about third-generation algal biofuels in recent years. Why would a company that manufactures and sells traditional fossil fuels be promoting an alternative biofuel? Are there other fuel companies that are doing similar promotional advertising? 
Teaching Suggestions
  • This article can be used to support teaching and learning of Biology and Technology & Engineering related to biofuels, fossil fuels and renewable energy. Concepts introduced include hydrocarbons, biofuels, ethanol, greenhouse gases, carbon dioxide, biodiesel, wind, Sun, renewable, first-generation biofuel, microorganisms, ferment, second-generation biofuels, cellulose, cellulosic biofuels, third-generation biofuels, algae, algal fuels and bioreactors.
  • After reading this article, teachers could have students complete a Concept Definition Web learning strategy to consolidate their understanding of the concept of biofuels. Ready-to-use Concept Definition Web reproducibles are available in [Google doc] and [PDF] formats. 
Teaching Suggestions
  • This article can be used to support teaching and learning of Biology and Technology & Engineering related to biofuels, fossil fuels and renewable energy. Concepts introduced include hydrocarbons, biofuels, ethanol, greenhouse gases, carbon dioxide, biodiesel, wind, Sun, renewable, first-generation biofuel, microorganisms, ferment, second-generation biofuels, cellulose, cellulosic biofuels, third-generation biofuels, algae, algal fuels and bioreactors.
  • After reading this article, teachers could have students complete a Concept Definition Web learning strategy to consolidate their understanding of the concept of biofuels. Ready-to-use Concept Definition Web reproducibles are available in [Google doc] and [PDF] formats. 

Learn more

Fossil Fuels 

Fact sheet by Hannah Ritchie & Max Roser for Our World in Data containing interactive graphs that detail global fossil fuel consumption. 

Bioenergy and Biofuels (2018)

Fact sheet from the International Energy Agency containing interactive graphs that detail global biofuel and bioenergy use. 

BiofuelNet Canada Infographics

Informative infographics containing information about different kinds of biofuels and their production. 

References

Aro, E. (2015). From first generation biofuels to advanced solar biofuels. Ambio, 45, 24-31. DOI: 10.1007/s13280-015-0730-0

IAS Score. (n.d.). Generations of biofuels.

International Energy Agency. (2007, January). IEA energy technology essentials.

National Geographic. (n.d.). Biofuels.

U.S. Energy Information Administration. (2019, February 13). Biofuels: Ethanol and biodiesel explained.