U. of I. engineers Paul Rozzi, professor Kyle Smith and JeongA Lee have developed a new battery-type device that captures CO2 from the air.
Photo Credit: Michelle Hassel
Scientific Frontline: Extended "At a Glance" Summary: Electrochemical Direct Air Capture
The Core Concept: A collaborative research team has developed a new, battery-like electrochemical device capable of directly extracting carbon dioxide from the atmosphere to combat climate change.
Key Distinction/Mechanism: Unlike traditional carbon capture technologies that rely on heat or target point sources, this system uses electricity and water-based chemistry. By utilizing proton-intercalation electrodes in a cation-compensated cell, the system manipulates the pH of a saltwater solution, making it alkaline to absorb carbon dioxide and then reducing the alkalinity to release the purified gas for storage.
Major Frameworks/Components:
- Specialized potassium-stabilized manganese dioxide electrodes.
- A cation-compensated electrochemical cell.
- Reversible proton-intercalation-mediated alkalization.
- Thermodynamic cycle modeling based on dissolved inorganic carbon and potassium ion concentration to map and optimize energy efficiency.
Branch of Science: Mechanical Engineering, Electrochemistry, Physical Chemistry, and Environmental Science.
Future Application: The technology is intended for large-scale direct air capture systems designed to operate anywhere, continuously scrubbing diffuse, legacy carbon dioxide from the environment, provided that engineering hurdles like inter-stream liquid mixing can be resolved.
Why It Matters: Most climate models indicate that reducing current emissions is insufficient to meet global climate targets. This technology directly addresses the vast amounts of legacy carbon dioxide already mixed into the atmosphere at low concentrations, offering a more practical and potentially energy-efficient removal pathway.
Engineers have developed a new way to pull carbon dioxide directly from the atmosphere using a process similar to charging and discharging a battery—an advance that could help address the planet’s excess \(\mathrm{CO_2}\) problem.
A new collaborative study between scientists at the University of Illinois Urbana-Champaign and Toyota focuses on direct air capture, a technology designed to reduce new emissions and remove \(\mathrm{CO_2}\) that has already accumulated in the atmosphere. Instead of using heat to absorb and release \(\mathrm{CO_2}\), as many carbon-capture methods do, the new method uses electricity and water-based chemistry within an electrochemical device.
The results of the study by mechanical engineering and science professor Kyle Smith, Illinois graduate students Paul Rozzi and JeongA Lee, and Chip Roberts and Tim Arthur from the Toyota Research Institute of North America are published in the journal Environmental Science and Technology.
Most climate scientists agree that even with aggressive cuts in current emissions, the world is unlikely to meet climate targets without also removing some of the \(\mathrm{CO_2}\) that has already accumulated over decades. Most current carbon-capture technologies work at point sources—places like power plant smokestacks where \(\mathrm{CO_2}\) emissions are high.
“Point-source methods are important, but they don’t deal with the vast amount of \(\mathrm{CO_2}\) already mixed into the air at much lower concentrations,” Smith said. “Our work is aimed at that legacy problem.”
A key advance of this work is the device’s use of specialized potassium-stabilized manganese dioxide electrodes and a specific method for moving charged particles. In the lab, the team uses an electrochemical cell to change the pH of a saltwater solution. In one step, the solution is made more alkaline, allowing it to absorb \(\mathrm{CO_2}\) from the air effectively. In another step, the solution is made less alkaline again, which causes the \(\mathrm{CO_2}\) to bubble back out in a purified form, ready for storage or reuse.
“What’s innovative about our work is that we use proton-intercalation electrodes in what we call a cation-compensated cell,” Smith said. “That design lets us operate in an alkaline range where \(\mathrm{CO_2}\) is much more soluble, which is crucial for making direct air capture practical.”
To make the system as efficient as possible, the team treated the process much like a classical thermodynamic cycle, in the spirit of the cycles engineers use to design power plants. Instead of thinking in terms of pressure and volume, the team mapped out their cycle using dissolved inorganic carbon and potassium-ion concentration in the solution.
“By framing our process as a thermodynamic cycle in this particular space, we could see where energy was being wasted and how to redesign the cycle,” Lee said.
While the early results are promising, the team said that there is still work to do before this technology can be deployed on a large scale. For example, the device uses two liquid streams that ideally should remain separate. In practice, some mixing occurs when flows are switched, reducing efficiency.
“Inter-stream mixing is one of the biggest issues we’re dealing with now,” Rozzi said. “If we can limit that mixing or design around it, we can significantly improve both energy consumption and productivity.”
“Our work with Professor Smith and the U. of I. team on electrochemical direct air capture provides useful insights into how materials, electrochemistry, and process design can be combined to address challenging \(\mathrm{CO_2}\) separation problems,” Roberts said. “This type of early-stage research supports Toyota’s broader effort to explore innovative pathways toward long-term decarbonization.”
Funding: Toyota Motor North America; the Campus Research Board at the U. of I., through an Arnold O. Beckman Award; the Department of Mechanical Science and Engineering; and The Grainger College of Engineering supported this research.
Published in journal: Environmental Science and Technology
Authors: Paul G. Rozzi, JeongA Lee, Vu Quoc Do, Timothy S. Arthur, Charles A. Roberts, and Kyle C. Smith
Source/Credit: University of Illinois Urbana-Champaign | Lois Yoksoulian
Edited by: Scientific Frontline
Reference Number: Eng071226_01