Engineers use moisture to pull carbon dioxide out of the air

Written by
Colton Poore, Andlinger Center for Energy and the Environment
March 18, 2024

Scientists have developed a way to capture and release carbon dioxide from the atmosphere by simply changing the surrounding humidity. This method relies on a type of ion-exchange resin, the surfaces of which are dotted with countless tiny pores, only 6 nanometers in diameter. The carbon capture process takes place inside these cavities during periods of low humidity.

The material could slash the energy costs associated with so-called direct air capture systems, which conventionally rely on energy-intensive temperature or pressure shifts to switch between carbon capture and release. By instead relying on humidity, the material could yield energy efficiency improvements over five times above current technologies. The researchers reported their findings in Environmental Science & Technology Letters on January 10.

“There’s been an explosion of interest in direct air capture systems, because they’re not just a way to reduce carbon emissions, but to actually remove them from the atmosphere,” said research leader Kelsey Hatzell, assistant professor of mechanical and aerospace engineering and the Andlinger Center for Energy and the Environment, pointing to a recent $3.5 billion effort from the U.S. Department of Energy to develop four regional direct air capture hubs across the country.

If scaled, the humidity-based regeneration approach could also present interesting opportunities to leverage the moisture fluctuations that naturally occur in the environment to further cut down on energy costs. 

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