In a paper recently published in Science Advances, researchers from the lab of Asst. Prof. Po-Chun Hsu in the Pritzker School of Molecular Engineering (UChicago PME) developed a distributed carbon nanofiber direct air capture filter that could potentially turn every home, office, school or other building into a small system working toward the global problem of airborne carbon dioxide.
A carbon nanofiber-based direct air capture filter developed by the University of Chicago Pritzker School of Molecular Engineering could turn existing building ventilation systems into carbon-capture devices while cutting homeowners’ energy costs. Through life cycle assessment, the air filter shows a carbon removal efficiency of 92.1% from cradle to grave.Photo by Elaina Eichorn
A life-cycle analysis shows that, even after factoring this extra CO2 released by everything from manufacture and transportation to maintenance and disposal, the new filter is more than 92% efficient in removing the gas from the air.
“Every building already has ventilation systems that move large volumes of air every day. By integrating our carbon-capture filters into these systems, we can remove carbon directly from the air without building new plants or using extra land,” said first author Ronghui Wu, an assistant professor at Nanyang Technological University who was a postdoctoral researcher in Hsu’s lab at the time of the research. “It’s a practical and scalable way to make carbon capture part of everyday infrastructure.”
On the largest possible level, replacing every building air filter with this new model could remove up to 596 megatonnes of carbon dioxide from the air—the equivalent of taking 130 million cars off the road for a year.
But on the individual level, every home, office or school that switch to direct air capture filters should expect lower energy bills. One study from 2024 indicated those savings could be up to about 21.6%.
“Normally, air-conditioning systems need to pull in a lot of outside air to keep indoor carbon dioxide levels low,” Wu said. “Our filter removes carbon dioxide inside the building, so the system doesn’t have to bring in as much outside air. That means less air needs to be heated or cooled, which reduces the energy consumptions in HVAC.”
Regenerated by sunlight
Current direct air capture technologies are massive, corporate-owned affairs requiring major investments in land, power and other resources. Hsu likens it to solar power—a technology once confined to utility-owned solar farms, but now a network of large farms and small rooftop panels working toward the same energy goal.
“These rooftop panels are possible because sunlight is more or less uniform. The CO2 from air is similar,” Hsu said. “We propose, using experiment and computation to demonstrate, that indeed we could retrofit our buildings to be part of the decarbonization effort.”
Creating a practical, real-world filter is a balancing act. The UChicago PME team had to ensure the filter removes more carbon from the air than the amount added by manufacturing, transporting, installing, maintaining and eventually disposing of it.
The team’s carbon nanofiber–based polyethylenimine material would create a reusable filter that could slot into existing HVAC systems, similar to the air-purifying high efficiency particulate arresting (HEPA) filters. Unlike HEPA filters, which head to landfills as garbage every six months to a year, the carbon-capture filters would have the carbon removed regularly and be returned to service.
Hsu and Wu envision an ecosystem where municipal waste management systems haul off the filters weekly with the garbage and recycling.
“They would have these saturated filters from household ventilation systems and commercial buildings, then replace them with new ones,” Hsu said. “They’d ship the saturated one to a centralized facility to dissolve the CO2 or make it into highly concentrated CO2 to capture or, even better, convert to high-value chemicals or fuel.”
The new material was specifically designed to show excellent solar absorptivity. This means the carbon can be removed from a saturated filter through solar thermal methods—including literally leaving the filter out under the sun.
“It has to be able to regenerate using renewable energy,” Hsu said. “The most common way to regenerate CO2 with solvent, is by heating it up. If you burn fossil fuels to heat up the solvent, then you will probably end up emitting more carbon dioxide than you capture.”
While the global benefits would rise as more places adopt the filter, lower energy bills aren’t the only benefits an individual would see from installing a direct air capture filter.
“This kind of air filter can also improve indoor air quality, especially in places like classrooms and offices where many people share the same space,” Wu said. “By keeping indoor carbon dioxide levels low, it helps people stay more alert, focused and healthy.”
