MSE PhD student proposes how we could use climate-warming CO2 for good

Phil De Luna (MSE PhD candidate) is first author on an analysis of how researchers could capture and recycle the greenhouse gas carbon dioxide. "If we continue to work at this, it’s a matter of time before we have power plants where CO2 is emitted, captured and converted,” De Luna says. (Credit: Tyler Irving)

Phil De Luna (MSE PhD candidate) is first author on an analysis of how researchers could capture and recycle the greenhouse gas carbon dioxide. “If we continue to work at this, it’s a matter of time before we have power plants where CO2 is emitted, captured and converted,” De Luna says. (Credit: Tyler Irving)

The thousands of metric tons of carbon dioxide (CO2) emitted from power plants each year doesn’t have to go into the atmosphere. Researchers are optimistic that within the next decade we will be able to affordably capture CO2 waste and convert it into useful molecules for feedstock, biofuels, pharmaceuticals, or renewable fuels. Now a team of U of T Engineering researchers and their U.S. collaborators describe their vision for what we should make with CO2 and how we can make it. Their opinion piece was published March 29 in the journal Joule.

“Similar to how a plant takes carbon dioxide, sunlight, and water to make sugars for itself, we are interested in using technology to take energy from the sun or other renewable sources to convert CO2 into small building block molecules which can then be upgraded using traditional means of chemistry for commercial use,” says Phil De Luna, a PhD candidate in the Department of Materials Science & Engineering. “We’re taking inspiration from nature and doing it faster and more efficiently.”

De Luna is first author on the paper along with postdoctoral fellow Oleksandr Bushuyev, both of whom are members of Professor Ted Sargent‘s (ECE) group.

Their analysis identified a series of possible small molecules that make economic sense and could be made by converting captured CO2. For energy storage needs, hydrogen, methane and ethane could be used in biofuels. Additionally, ethylene and ethanol could serve as the building blocks for a range of consumer goods, and CO2-derived formic acid could be used by the pharmaceutical industry or as a fuel in fuel cells.

While current technologies that can capture CO2 waste are still in their infancy, with new startups currently developing strategies for commercial use, the researchers envision that the coming decades will bring major improvement to make CO2 capture and conversion a reality. Within five to 10 years, electrocatalysis — which stimulates chemical reactions through electricity — could be a way into this process. And 50 years or more down the line, molecular machines or nanotechnology could drive conversion.

“This is still technology for the future,” Bushuyev says, “but it’s theoretically possible and feasible, and we’re excited about its scale up and implementation. If we continue to work at this, it’s a matter of time before we have power plants where CO2 is emitted, captured and converted.”

The authors are aware of the limitations of carbon capture and conversion. First, it has been criticized for not being economically feasible, particularly because of the cost of electricity to make these chemical reactions take place, but this will likely go down as renewable energy becomes widespread over time. Second, there are few factories with a high carbon footprint that emit pure CO2, which is necessary for conversion, but technology that could help with this issue is in development.

“The motivation to write this piece is that we wanted clear insight into whether this could be economically viable, and whether it’s worth the time to invest in it,” De Luna says. “This paper images a pathway for what we can do with carbon dioxide conversion in the coming decades.”

Many insights for the analysis were developed in collaboration with Ling Tao, Genevieve Saur and Jao van de Lagemaat at the U.S. National Renewable Energy Laboratory.

Published by Engineering Communications with files from Joseph Caputo, Cell Press