Building a better carbon capture system

Carbon capture has been hailed as a ground-breaking technology for cleaning the air. And it is, but there are some drawbacks – it’s expensive, and most technology requires the generation and application of heat, which creates emissions.

There had to be a better way, thought Dr. Haotian Wang, associate professor in the Department of Chemical and Biomolecular Engineering at Rice University at Houston, Texas.

Wang and his team found it in a process of electrolysis they studied at Rice and collaborated on with the Canadian Light Source (CLS) at the University of Saskatchewan. They have devised a modular solid electrolyte reactor that, in time, will be usable everywhere, in industry but also for “household use, small business use, space station, submarine, any enclosed environment,” he said. Their study was published in the journal Nature.

“Our new approach is integrated capture and regeneration, which means that you can continuously concentrate the carbon dioxide from dilute sources into almost 100 percent purity.”

The reactor is divided into three chambers. Electrolysis, a process by which electric current is passed through a substance to effect a chemical change, occurs on two sides — one performing oxygen reduction and the other oxygen evolution. The oxygen reduction reaction creates an alkaline environment, which captures carbon and then releases it in the central chamber.

The carbon can either be stored underground or converted to valuable products such as alcohols, “which is also an important direction we are working on,” Wang said.

Crucially, no chemical inputs other than water are required and no side products are generated.

Wang has estimated that the cost of capturing carbon will be $83 per ton, but with improvements, that could drop to $58 or even $33 per ton, a big saving from today’s costs, which range from $125 to $600 USD.

“It’s not only the cost but also the energy source that we can use, which is electricity,” he said. “Ideally, we want to transform this into an electrifying process because in the future we can get a lot (of clean electricity) from solar farms, wind farms and nuclear power plants.”

The CLS played an important role in this work.

“We have a very long-term history with CLS,” he said. “We used the Soft X-Ray Microcharacterization Beamline (SXRMB) to characterize the catalyst, to confirm the atoms are isolating and not clustering together.”

Wang said the modular reactor technology should be ready for use in years, not decades.

“We have a start-up company to try to accelerate the process to make this technology available to users.”

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Zhu, P., Wu, ZY., Elgazzar, A. et al. Continuous carbon capture in an electrochemical solid-electrolyte reactor. Nature 618, 959–966 (2023). https://doi.org/10.1038/s41586-023-06060-1

Photos: Canadian Light Source | SXRMB Beamline | Haotian Wang

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Greg Basky
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Canadian Light Source
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greg.basky@lightsource.ca