Scientists Unveil Cheaper, Smarter Way To Capture Carbon Dioxide

By repurposing the cold energy from LNG processing, scientists have developed a new, cost-efficient technique to trap carbon dioxide from the air using advanced sorbent materials.

Scientists at Georgia Tech’s School of Chemical and Biomolecular Engineering (ChBE) have introduced a new method aimed at reducing carbon dioxide (CO₂) levels in the atmosphere, a key strategy for addressing climate change.

Although various direct air capture (DAC) technologies have emerged in recent years, their widespread use has been limited due to high costs and energy demands.

In a recently published study in Energy & Environmental Science, the Georgia Tech team unveiled a more cost-effective and energy-efficient way to capture CO₂ by using very cold air and commonly available porous sorbent materials, opening the door for broader application of DAC in the future.

Harnessing Already Available Energy

The approach, developed in collaboration with researchers from Oak Ridge National Laboratory in Tennessee and from Jeonbuk National University and Chonnam National University in South Korea, involves integrating DAC with the regasification process of liquefied natural gas (LNG). This industrial step, which turns LNG back into gas for use, generates extremely low temperatures that can be repurposed for efficient CO₂ capture.

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.”

Reference: “Near-cryogenic direct air capture using adsorbents” by Seo-Yul Kim, Akriti Sarswat, Sunghyun Cho, MinGyu Song, Jinsu Kim, Matthew J. Realff, David S. Sholl and Ryan P. Lively, 24 June 2025, Energy & Environmental Science.
DOI: 10.1039/D5EE01473E

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