By Isaac Gendler

When people talk about renewable energy, they usually refer to solar, wind and geothermal sources. These are generally the domain of physical mechanical processes that have no reliance upon any living organisms. As a result, students who wish to work in this field typically enter Engineering and the Physical Sciences.

But what if the life sciences could also play a role in the new energy paradigm? Enter the fascinating world of bioenergy.

Biodiesel

Most vehicles run on petroleum-based fuels, whether it be the cars on the road or the planes in the sky. Not only is this toxic for the environment, but it can also create a variety of economic and trade issues. And worst of all, there is only a limited supply of them in the ground.

But what if we could obtain our fuel from a renewable resource instead?

Biodiesel ​is the answer to this.​ ​Biodiesel is oil that is derived from organic matter. Typically, this is the fats and oils found in crops and (very rarely) meat. Biodiesel is produced by chemically reacting lipids (such as vegetable and soybean oil) with alcohol. Biodiesel is commonly mixed with regular petroleum to bring down the average lifecycle emission levels of the fuel. One drawback of biodiesel is that if it is a low-quality variant or too much is used then the engine can be damaged.

Ethanol

If you think that getting gasoline from food sounds delicious, then you’re in for a treat. It turns out that corn or other sugar-based crops can also be turned into a fuel! Through a complex process of milling, mashing, and fermenting in industrial facilities, an energy dense substance known as ​Ethanol ​can be made.

One of the most popular applications of ethanol is in serving as a vehicle fuel. Ethanol from ethanol stations is typically not pure ethanol (since that would be too corrosive) but ​E-85​, which is a mixture of 85% ethanol and 15% petroleum, is three quarters as energy dense than petroleum. This means that you would have to burn four cans of E-85 to get the energy equivalent of three cans of petroleum (check out ​U.S. Energy Information Administration – EIA – Independent Statistics and Analysis for more details). Despite this, ethanol emits much less pollution into the atmosphere and runs much cleaner in the engine.

A vehicle’s engine needs to be modified to run on ethanol. Around 87% of vehicles in Brazil (an important country for ethanol production) and 7% in the United States have this upgrade. Vehicles that are ready for ethanol are known as “Flexfuel” vehicles.

Algae Bioenergy

What if you like the idea of getting energy from a food crop but you’re not the biggest fan of Ethanol? After all, growing crops such as corn can take a long time and use up a lot of water. Luckily for you there is an answer in the form of ​Algae Bioenergy.

Algae is a category for rootless, stemless, leafless (and usually unicellular) microorganisms that obtain their energy from photosynthesis. This makes them completely renewable and even offers the potential to sequester carbon dioxide. Algae can begin as a single cell organism and can then be grown out in aquatic raceways, drained and pulled out when the time comes for energy extraction. This dried Algae can then be transformed into oil, making it useful as a fuel. What makes Algae so unique is that not only can it be used in an internal combustion engine without having to modify the engine but the fact that growing algae takes carbon out of the atmosphere can make Algae somewhat of a carbon negative fuel!

Bioenergy Metrics

Although there are many different sources of bioenergy, we need some way to measure how effective they are. We can do this using something called ​Bioenergy Metrics.  The most basic metrics focus on the productivity of the feedstocks. ​Primary Productivity ​is the actual rate at which plants store energy, the ​Gross Primary Productivity ​is the summation of all photosynthetic activity, and the ​Total Primary Productivity ​is the net transfer of carbon from the atmosphere into green plants per unit time (basically how much useful net energy is created by ecosystem plants in a given time).

Final Thoughts

Biological feedstocks can play an important role in renewable energy. Whether it be from the corn we eat or the algae we see in the aquarium, there are novel sources of energy that can be found anywhere. All it takes is a little bit of scientific knowledge and engineering ingenuity.

Recommended Reading:

Bioenergy ​ . Department of Energy https://www.energy.gov/science-innovation/energy-sources/renewable-energy/bioenergy

U.S. Energy Information Administration – EIA – Independent Statistics and Analysis. ​ Few Transportation Fuels Surpass the Energy Densities of Gasoline and Diesel – Today in Energy – U.S. Energy Information Administration (EIA), U.S Energy Information Administration, 13 Feb. 2013, www.eia.gov/todayinenergy/detail.php?id=9991#.

Emerging Topics in Life Sciences – Adapting to Climate Change: People and Biology http://www.emergtoplifesci.org/content/3/2

About the Author

I am a soon to be graduating undergraduate student in Mechanical Engineering and Mathematics at San José State University in California. I am interested in pursuing graduate school and consulting opportunities related to renewable energy and sustainability. In my spare time, I like to write on my daily science blog and learn other languages. Feel free to reach out to me on LinkedIn and Twitter..