“Millions of years ago, when dead plants and animals were buried under the ground and in the presence of extreme temperature and pressure conditions, fossil fuels like coal, petroleum, and natural gas were generated,” explained Tirumareddy, who is currently pursuing a PhD in chemical engineering at USask’s College of Engineering.
In fact, 80 per cent of the world’s energy needs are met by using fossil fuels, but global reserves of these fuels are limited and will run out. The usage of fossil fuels generates large amounts of carbon emissions contributing to global warming. Tirumareddy stresses that finding alternatives quickly can help protect future generations from being deprived of necessary energy sources.
One option is to harness the energy in the non-edible portions of plants, like the hull of an oat, crushed canola meal, or spent coffee grounds, as the basis of a biofuel.
Biofuel theoretically acts the same way as fossil fuel but is instead solely made of plant-based materials, which are more easily generated in nature compared to the ancient fossil fuels.
“To reduce the carbon intensity in the atmosphere, Canada has set some renewable fuel regulations. According to these regulations, fuel producers need to blend gasoline and diesel with at least five per cent and two per cent ethanol and biodiesel, respectively,” said Tirumareddy. “To meet these fuel standards, there is a huge demand for renewable fuels. Currently, biomass is the sole source of renewable fuels for the transportation sector that can be used within the prevailing fossil fuel infrastructure, so our goal is identifying sustainable options for plant-based materials to create this fuel.”
Tirumareddy is working under the supervision of Dr. Ajay Dalai (PhD), a distinguished professor at USask and Canada Research Chair in Bioenergy and Environmentally Friendly Chemical Processes, who has conducted globally renowned research programs that look at using biofuels to address worldwide environmental concerns.
“In our lab, we are able to create similar conditions [to those that created fossil fuels] on a pilot scale where biomass is mixed with water and converted into biofuels in the presence of moderate temperature and high pressure. This process is called hydrothermal liquefaction,” said Tirumareddy. “Out of all the different feedstock types, mustard meal and canola meal produced bio-oil with high yield and good quality.”
Further analysis of the raw materials revealed that canola and mustard meals have some special chemical characteristics that allow them to convert into an oil product that is potentially useful. A problem, though, is that the oil produced is thick and doesn’t blend easily with petroleum, which is necessary for use in machinery like automobiles.
To address this issue, Tirumareddy said the oxygen content of the substance is key.
“The highly viscous nature of the bio-oil is due to the presence of many hetero-compounds and a large amount of oxygen, whereas petroleum crude oil has less oxygen content,” said Tirumareddy. “By removing the oxygenated compounds, we can produce high-quality bio-oil which can be blended with petroleum crude and can be used in the transport sector.”
Tirumareddy said a perk of producing biofuels is that the process nets zero carbon emissions, whereas typically, the energy sector is responsible for a large portion of global carbon emissions.
“Biomass materials use carbon dioxide from the atmosphere to grow and their use as fuel emits carbon dioxide to the environment, making the overall process carbon neutral,” she said.
With her work published in multiple book chapters and being prepared for submission to an academic journal, Tirumareddy said her research is far from complete.
“I was born and brought up in a small village in India. During my childhood, I was always surrounded by trees and agricultural fields,” said Tirumareddy. “When I grew up and moved to a city to study, I started becoming concerned about pollution, water, energy scarcity, and other environmental challenges. This led me to take up chemical engineering as my career prospective.
Research funding to support Tirumareddy’s work was provided by the Natural Sciences and Engineering Council of Canada, Mitacs, NULIFE Green Tech, and Western Economic Diversification Canada.
This article first ran as part of the 2023 Young Innovators series, an initiative of the USask Research Profile and Impact office in partnership with the Saskatoon StarPhoenix.