Study demonstrates low-cost method to remove CO₂ from air using cold temperatures, common materials

(Press-News.org) Researchers at Georgia Tech’s School of Chemical and Biomolecular Engineering (ChBE) have developed a promising approach for 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 DAC implementation.

However, in a new study published in Energy & Environmental Science, the research team demonstrated techniques for capturing CO₂ more efficiently and affordably using extremely cold air and widely available porous sorbent materials, expanding future deployment opportunities for DAC.

Harnessing Already Available Energy

The research team – including members from Oak Ridge National Laboratory in Tennessee and Jeonbuk National University and Chonnam National University in South Korea – employed a method combining DAC with the regasification of liquefied natural gas (LNG), a common industrial process that produces extremely cold temperatures.

LNG, which is a natural gas cooled into a liquid for shipping, must be warmed back into a gas before use. That warming process often uses seawater as the source of the heat and essentially wastes the low temperature energy embodied in the liquified natural gas. 

Instead, by using the cold energy from LNG to chill the air, Georgia Tech researchers created a superior environment for capturing CO₂ using materials known as “physisorbents,” which are porous solids that soak up gases.

Most DAC systems in use today employ amine-based materials that chemically bind CO2 from the air, but they offer relatively limited pore space for capture, degrade over time, and require substantial energy to operate effectively. Physisorbents, however, offer longer lifespans and faster CO₂ uptake but often struggle in warm, humid conditions.

The research study showed that when air is cooled to near-cryogenic temperatures for DAC, almost all of the water vapor condenses out of the air. This enables physisorbents to achieve higher CO₂ capture performance without the need for expensive water-removal steps.

“This is an exciting step forward,” said Professor Ryan Lively of ChBE@GT. “We’re showing that you can capture carbon at low costs using existing infrastructure and safe, low-cost materials.”

Cost and Energy Savings

The economic modeling conducted by Lively’s team suggests that integrating this LNG-based approach into DAC could reduce the cost of capturing one metric ton of CO₂ to as low as $70, approximately a threefold decrease from current DAC methods, which often exceed $200 per ton.

Through simulations and experiments, the team identified Zeolite 13X and CALF-20 as leading physisorbents for 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.

These materials showed strong CO₂ adsorption at -78°C (a representative temperature for the LNG-DAC system) with capacities approximately three times higher than those found in amine materials that operate at ambient conditions. They also released the captured and purified CO₂ with low energy input, making them attractive for practical use.

“Beyond their high CO2 capacities, both physisorbents exhibit critical characteristics such as low desorption enthalpy, cost efficiency, scalability, and long-term stability, all of which are essential for real-world applications,” said lead author Seo-Yul Kim, a postdoctoral researcher in the Lively Lab.

Leveraging Existing Infrastructure

The study also addresses a key concern for DAC: location. Traditional systems are often best suited for dry, cool environments. But by leveraging existing LNG infrastructure, near-cryogenic DAC could be deployed in temperate and even humid coastal regions, greatly expanding the geographic scope of carbon removal.

“LNG regasification systems are currently an untapped source of cold energy, with terminals operating at a large scale in coastal areas around the world,” Lively said. “By harnessing even just a portion of their cold energy, we could potentially capture over 100 million metric tons of CO₂ per year by 2050.”

As governments and industries face increasing pressure to meet net-zero emissions goals, solutions like LNG-coupled near-cryogenic DAC offer a promising path forward. The next steps for the team include continued refinement of materials and system designs to ensure performance and durability at larger scales.

“This is an exciting example of how rethinking energy flows in our existing infrastructure can lead to low-cost reductions in carbon footprint,” Lively said.

The study also demonstrated that an expanded range of materials could be employed for DAC. While only a small subset of materials can be used at ambient temperatures, the number that are viable grows substantially at near-cryogenic temperatures.

“Many physisorbents that were previously dismissed for DAC suddenly become viable when you drop the temperature,” said Professor Matthew Realff, co-author of the study and professor at ChBE@GT. “This unlocks a whole new design space for carbon capture materials.”

Citation: Seo-Yul Kim, Akriti Sarswat, Sunghyun Cho, MinGyu Song, Jinsu Kim, Matthew J. Realff, David S. Sholl, and Ryan P. Lively, “Near-Cryogenic Direct Air Capture using Adsorbents,” Energy & Environmental Science, 2025.

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