Many governments and businesses worldwide have been trying to devise effective initiatives aimed at mitigating climate change and global warming. So far, their primary focus has been to reduce the emission of carbon dioxide (CO2), methane (CH4) and other greenhouse gases, for instance via the introduction of electric vehicles, solar panels and other sustainable technologies or energy solutions.
Some energy engineers, however, have also been exploring the possibility of directly removing these gases from the air, an approach known as direct air capture. Despite their potential, most direct air capture systems introduced so far either consume too much energy (6–10 gigajoules per ton of CO2 captured) or degrade rapidly over time.
Researchers at Northwestern University and California Institute of Technology recently introduced a new electrified mineral-based system that could remove CO2 from the atmosphere more efficiently and reliably. This system, presented in a paper published in Nature Energy, was developed by Prof. Ted Sargent’s group in collaboration with Prof. Omar K. Farha.
“Direct air capture can help address hard-to-abate emissions derived from aviation, shipping, cement, etc.) and could reduce the total amount of CO? already accumulated in the atmosphere,” Prof. Ted Sargent, co-senior author of the paper, told Tech Xplore. “Even with aggressive emissions cuts, most net-zero plans assume we’ll need some form of carbon removal for leftover, hard-to-eliminate emissions. The paper frames electrified DAC as a route toward net-negative emissions when powered by low-carbon electricity.”
An electricity-driven direct air capture system
Direct air capture systems introduced in the past relied on either liquid carbonate solutions or organic sorbents. The first are water-based chemicals that react with CO2 and form carbon compounds, while the latter are carbon-based materials that bind gases.
Unfortunately, both these types of solutions were found to come with limitations. Systems based on liquid carbonate solutions consume large amounts of energy, while organic sorbents can quickly degrade when exposed to oxygen, adversely impacting a system’s performance.
Sargent, Xie and their colleagues introduced a new electricity-driven direct air capture system that instead relies on the common mineral manganese oxide (MnO?). This inorganic material can capture CO? from air when it is electro-chemically charged, and can then release it if the voltage bias is switched.
“After optimizing how it’s operated, the system captures CO? from realistic air conditions (0.04% CO? and 21% oxygen) using ~4 GJ of energy per ton of CO? captured, while maintaining low sensitivity to oxygen and humidity,” explained Zeyan Liu, first author of the paper.
“Direct air capture is difficult because CO? is extremely dilute in air and the process must work in the presence of oxygen and humidity—two factors that affect sorbent performance or durability (e.g. organic amines or quinones are oxygen sensitive). This work reports a new path that remains effective under those conditions.”
New avenues for the mitigation of climate change
The researchers evaluated their proposed system in an initial experiment, which yielded very promising results. They found that their system could capture 80% of CO? in the air in a single cycle, all while consuming 4.1 GJ per ton of CO?, which is significantly less than many systems introduced in the past.
The mineral used by the researchers also appeared to be far more durable than organic sorbents used in the past, as it was not as strongly affected by oxygen exposure. After operating for over 1000 hours, the system was found to retain over 90% of its initial capacity.
“Instead of relying on large pH swings (common in electrified liquid systems) or oxygen-sensitive organic capture molecules, this paper shows a route using an inorganic, redox-active mineral sorbent that can be activated with voltage control,” said Xie. “This mechanism may enable new electrochemical contactor design and application in scenarios (e.g. highly humid environments) that are challenging for other capture technologies.”
The electrically driven direct air capture system introduced by the researchers could soon be improved further, scaled up and evaluated in real-world settings. In the future, it could potentially contribute to ongoing efforts aimed at reducing pollution and stabilizing the climate on Earth.
“Our paper is a proof-of-concept, first demonstration of carbon capture using a reversible surface mineralization mechanism,” added Xie. “The next step would be designing a new electrochemical contactor to improve real-world performance metrics, such as areal cost and productivity, and to move the technology forward along the technology readiness level (TRL) spectrum.”
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Publication details
Zeyan Liu et al, Electrified reversible surface mineralization of CO2 for direct air capture, Nature Energy (2026). DOI: 10.1038/s41560-026-01989-9.
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