We can use climate-warming carbon dioxide for good, U of T researchers say

The thousands of tonnes of carbon dioxide (CO₂) emitted from power plants each year doesn’t have to go into the atmosphere. 

Researchers are increasingly 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. 

In an opinion piece published March 29 in the journal Joule, a team from the University of Toronto’s Faculty of Applied Science & Engineering and their U.S. collaborators lay out their vision for what we should make with CO2  – and how we can make it.

“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 and 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 University Professor Ted Sargent's group.  

Their analysis identified a series of possible small molecules that could be made economically 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 technologies that can capture CO₂ waste are still in their infancy, with new startups currently developing strategies for commercial use, the researchers envision major improvements in the coming decades 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.

Read the opinion piece in the journal Joule

“This is still technology for the future,” says Bushuyev, “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 high cost of electricity to make these chemical reactions take place. But this will likely go down as renewable energy becomes more widespread. 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, adding the paper imagines a pathway "for what we can do with carbon dioxide conversion in the coming decades.”

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.

With files from Joseph Caputo, Cell Press