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Pioneering Plant-Based Jet Fuels

Chemical Engineering Student Optimizes Jet Fuel Additives While Reducing Carbon Emissions

An encounter at a school event sparked junior Sara Murphy’s passion for biofuels.

During the University of Idaho’s Palousafest, Murphy met members of the Vandal Clean Energy Club, an organization that promotes and implements clean energy and sustainable practices in and around U of I. A major initiative of the club is reacting vegetable oil waste from campus food facilities with alcohol to create biodiesel, which can then be used in university diesel vehicles.

“When I go to career fairs and talk about how I have made biodiesel and worked on a continuous flow process, that blows people out of the water,” said Murphy, now the vice president of the club.

Since connecting with the club, Murphy, a 20-year-old chemical engineering major and political science minor, has researched plant-based jet fuel additives modeled after biodiesel to address two issues: cost and energy density — the energy stored in a certain amount of fuel.

I really wanted to get into political science to understand government and political structure so that not only can I do the research, but I can also see it instituted or mandated.
Sara Murphy

According to the National Renewable Energy Laboratory, biofuel is considered a renewable energy source while petroleum-based fuels are not. In addition, biofuels burn cleaner than petroleum-based fuels. The difference in efficiency in petroleum-based fuel samples and biofuel samples is visible when watching the two burn alongside each other, especially in the amount of black soot produced, Murphy said.

“This difference is what we call the combustion efficiency,” said Murphy. “Any black soot is unburnt fuel, which represents inefficiency and a loss of money.”

A Promising Plant-Derived Candidate

The basic ingredients for the jet biofuel — vegetable oil and alcohol — are derived from plants. For her study, the Boise native reacted components of vegetable oil with two plant-derived and two non-plant-derived alcohols to create different jet biofuels for testing.

To learn which biofuels are viable as jet biofuel, Murphy is testing the cloud point, or the point at which the fuel will freeze at cold temperatures. Jet fuel must perform well in the freezing temperatures encountered at the high elevations at which the planes fly.

“There’s no point of testing anything else if a fuel freezes when you’re high in the atmosphere,” said Murphy.

Murphy hypothesized that the structure of the alcohol molecules will influence the cloud point and determine overall fuel performance. With guidance from her research mentor, Professor Dev Shrestha with the College of Engineering, and recent master’s graduate Brian Hanson, Murphy is continuing to conduct her research with the biofuel made from plant-derived alcohol isobutanol, which exhibited the lowest cloud point and hit target energy density.

“In my experiments, isobutanol-based biofuel didn’t even start to freeze until minus 58 degrees Celsius, and Jet A, the typical jet fuel we use in most commercial airlines, freezes solid at minus 40 degrees Celsius,” said Murphy.

Murphy is further testing isobutanol to ensure it is the best candidate for jet biofuel.

Murphy watches two metal pans of fuel burn.
Sara Murphy monitors two different samples of jet fuel burning. The petroleum-based fuel emits more smoke than the plant-based fuel.

Campus Sustainability

While Murphy continues her research on sustainable fuel options, she is also seeking to further promote sustainability on the Moscow campus. She and the Vandal Clean Energy Club have helped U of I run their six vehicles, including the BioBug — U of I’s biodiesel Volkswagen Beetle — on biodiesel produced by students in the club.

In October, Murphy met with University of Idaho President Scott Green to discuss using a 20% biodiesel blend in all diesel engines on the Moscow campus to reduce the carbon impact of the university. To that end, the Vandal Clean Energy Club won a Sustainability Center grant and refurbished an old biodiesel fuel station on campus. The next step will be to produce and distribute the biodiesel made by the students.

“President Green was really passionate about the fact that the biodiesel lab provides students with hands-on opportunities to experience advanced biofuels and to continue the history of biodiesel at the University of Idaho,” said Murphy.

Plans of how to potentially distribute the biodiesel are being discussed.

Murphy stands in a lab with her lab coat and a shirt with the periodic table on it.
Sara Murphy is the vice president of the Vandal Clean Energy Club.

Building a Resume to Make a Difference

Last year, Murphy added a political science minor to her studies after realizing the value of her jet biofuel research to create change.

“I really wanted to get into political science to understand government and political structure so that not only can I do the research, but I can also see it instituted or mandated,” said Murphy. “I think it’s really important that we start having more engineers or scientists creating policy.”

For Murphy, this interest arose following a family vacation to Alaska her senior year of high school.

While visiting a popular glacier, Murphy noticed that the markers representing the amount of recession of the glacier over the years increased noticeably beginning in the 1990s.

“How can I sit by and not do something about this?” said Murphy, who grew up skiing and hiking and said she wants to continue to enjoy the outdoors. “I didn’t know how I could see something this powerful and not feel obligated to do something.”

Murphy thinks there’s a disconnect between the scientific community and the policymakers from around the world.

“It’s critical to combine the science with the politics, and having more people who understand both of those worlds and are able to bring them together is key, especially when it comes to the environment and climate change,” Murphy said.

Article by Jordan Hawley, a senior from Emmett, who is studying microbiology.

Photos by Valerie Blackburn, a junior from Idaho Falls, who is studying advertising and film and television.

Sara Murphy is an OUR Summer Undergraduate Research Fellowship recipient.

This project was funded by United States Department of Agriculture National Institute of Food and Agriculture award 2014-45300-22312. The total project funding is $908,554, of which 100% is the federal share.

Published in March 2020.

Two fuels burn side-by-side in small metal pans.
The petroleum-based fuel emits more smoke than the plant-based fuel.

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