A low-cost method can remove Co2 from the air using cold temperatures and common materials

Researchers at Georgia Tech’s Faculty of Chemistry and Biomolecular Engineering (CHBE) have developed a promising approach to removing carbon dioxide (CO₂) from the atmosphere to help mitigate global warming.

While promising technologies for direct air capture (DAC) have emerged over the past decade, high capital and energy costs have hindered the implementation of DACs.

However, in a new study published in Energy & Environmental Science, the research team demonstrated technology for more efficient and affordable capture of extremely cold air and widely available porous adsorbent materials, expanding the opportunities for future deployment of DACs.

It’s already using available energy

A research team, including members of the Oak Ridge National Laboratory in Tennessee and the Chonbuk National University in Korea, hired a method of combining DACs to readjust liquefied natural gas (LNG), a common industrial process that produces extremely cold temperatures.

LNG is natural gas that is cooled to liquid for transportation, so it must be returned to the gas before use. That warming process often uses seawater as a source of heat, wastes cold energy embodied in essentially liquefied natural gas.

Instead, by using the cold energy of LNG to cool the air, researchers at Georgia Tech have created a great environment for capturing CO2 using a material known as “physorbents,” a porous solid that absorbs gas.

Most DAC systems currently in use employ amine-based materials that chemically bond CO2 from air, but provide relatively limited pore space for capture, degrades over time and requires considerable energy to operate effectively. However, physics offers longer lifespans and faster core takes, but often struggles in warm, humid conditions.

Research studies showed that almost all water vapor condenses from the air when air is cooled close to the DAC’s cell-forming temperature. This allows physisorbents to achieve higher CO₂ capture performance without the need for an expensive water removal step.

“This is an exciting step,” said Professor Ryan Lively of Chbe@GT. “It demonstrates that carbon can be captured at a low cost using existing infrastructure and safe, low-cost materials.”

Cost and energy savings

Economic modeling carried out by the Lively team suggests that by integrating this LNG-based approach into the DAC, the cost of capturing a metric ton of CO2 up to $70 can be reduced.

Through simulations and experiments, the team identified Zeolite 13x and Calf-20 as the main physisorbents in this DAC process. Zeolite 13X is an inexpensive and durable desiccant material used in water treatment, while Calf-20 is a metal organic framework (MOF) known for its stability and CO2 capture performance from Flue gas, but not from air, for its CO2 capture performance.

These materials exhibited strong coadsorption at -78°C (typical temperatures for LNG-DAC systems) with a volume about three times higher than those found in amine materials operating under ambient conditions. They also released captured and purified CO₂ on low energy inputs, making them practically attractive.

“Beyond high CO2 capacity, both physics exhibit important properties such as low desorption enthalpy, cost-effectiveness, scalability, and long-term stability. All of these are essential for real-world applications.”

Utilizing existing infrastructure

This study also addresses important DAC: location concerns. Traditional systems are often ideal for dry, cool environments. However, by leveraging existing LNG infrastructure, nearly encrypted DACs can be deployed in temperate and humid coastal regions, significantly expanding the geographical scope of carbon removal.

“The LNG regasification system is currently an undeveloped cold energy source, with terminals operating on a large scale in coastal regions around the world,” Lively said. “Even a portion of their cold energy could potentially capture more than 100 million tons of CO2 per year by 2050.”

As governments and industries face increasingly pressure to achieve net-zero emissions targets, solutions like LNG-coupled near-replica DACs offer a promising path forward. The team’s next steps include continuous improvements to materials and system designs to ensure performance and durability at a larger scale.

“This is an exciting example of how rethinking energy flows with existing infrastructure can lead to lower cost savings in carbon emissions,” Lively says.

This study also demonstrated that an extended range of materials can be adopted in DACs. Although only a small subset of materials available at ambient temperatures are available, the number of viable increases significantly at almost intrinsic temperatures.

“Many physicists who were previously rejected for the DAC suddenly become feasible when they lower the temperature,” says Professor Matthew Realff, a co-author of the study and professor at Chbe@GT. “This will unlock a whole new design space for carbon capture materials.”