Engineers have developed a new device that removes carbon dioxide (CO₂) directly from the air using electricity and a saltwater-based chemical process.
The technology works much like a rechargeable battery, offering a potentially more energy-efficient way to capture one of the main greenhouse gases driving climate change.
The research is the result of a collaboration between the University of Illinois Urbana-Champaign and Toyota Research Institute of North America.
The findings have been published in the journal Environmental Science & Technology.
Scientists widely agree that reducing future emissions alone will not be enough to slow global warming.
Large amounts of carbon dioxide have already built up in Earth’s atmosphere over many decades, and many climate experts believe that some of this existing CO₂ must also be removed to meet international climate goals.
Most current carbon capture systems focus on collecting CO₂ from concentrated sources such as power plants or industrial facilities before the gas enters the atmosphere.
While these systems are important, they cannot remove the carbon dioxide that has already spread throughout the air.
The new technology is designed specifically for this challenge, a process known as direct air capture.
Unlike many existing direct air capture systems, which rely on heat to trap and release carbon dioxide, the new device uses electricity to drive a series of chemical reactions in a saltwater solution. This approach could make the process easier to power with renewable electricity.
At the heart of the system are specially designed electrodes made with potassium-stabilized manganese dioxide. When electricity flows through the device, it changes the acidity, or pH, of the saltwater solution.
In one stage, the solution becomes more alkaline, allowing it to absorb carbon dioxide from the surrounding air. In the next stage, the electrical current changes the solution back to a less alkaline state. This causes the dissolved carbon dioxide to separate from the liquid and bubble out as a concentrated gas that can be captured, stored underground or reused in industrial processes.
The researchers describe this sequence as similar to charging and discharging a battery, with electricity controlling when the solution absorbs and releases carbon dioxide.
To improve efficiency, the team analyzed the process using principles commonly applied to power plants and engines. Instead of studying pressure and temperature, they focused on how the concentrations of dissolved carbon dioxide and potassium ions changed throughout the system.
This allowed the researchers to identify where energy was being lost and redesign parts of the cycle to make the process more efficient.
Although the early laboratory results are encouraging, the technology still faces challenges before it can be used on a commercial scale.
One of the biggest problems is preventing two different liquid streams inside the device from mixing. Ideally, the liquids remain separate, but during operation some mixing occurs, reducing both efficiency and productivity. The researchers say finding ways to minimize this mixing will be an important next step in improving the technology.
The team believes the study demonstrates how advances in materials science, electrochemistry and engineering can work together to create new solutions for removing carbon dioxide from the atmosphere.
While more development is needed, the battery-like system represents another promising approach in the growing effort to combat climate change.
If successfully scaled up, it could become part of a broader strategy that combines emissions reductions with technologies capable of removing carbon dioxide already present in the air, helping move society closer to long-term climate goals.
