In a significant advancement for climate change mitigation, researchers at the Georgia Institute of Technology have unveiled a novel method for capturing carbon dioxide (CO₂) that leverages the cold energy released during liquefied natural gas (LNG) processing. This innovative approach promises a more cost-effective and energy-efficient solution for reducing greenhouse gas emissions, potentially transforming the landscape of carbon capture technologies.
The research, conducted in collaboration with Oak Ridge National Laboratory and institutions in South Korea, focuses on integrating direct air capture (DAC) systems with the regasification process of LNG. Typically, LNG is transported in a liquefied state and must be reheated to return to a gaseous form for use. This regasification process releases substantial amounts of cold energy, which is often dissipated into the environment. The Georgia Tech team proposes harnessing this otherwise wasted cold energy to enhance the efficiency of CO₂ capture from the atmosphere.
Central to this method is the use of “physisorbents,” porous materials that physically adsorb gases. Unlike traditional amine-based sorbents that chemically bind CO₂ and require significant energy for regeneration, physisorbents operate effectively at low temperatures and offer longer lifespans. However, their performance has been limited in warm, humid conditions due to moisture interference. By cooling the air to near-cryogenic temperatures using LNG’s cold energy, water vapor condenses out, creating optimal conditions for physisorbents to function efficiently.
The study identified materials such as Zeolite 13X and CALF-20 as particularly effective physisorbents under these conditions. Zeolite 13X, commonly used in water treatment, and CALF-20, a metal-organic framework known for flue gas CO₂ capture, demonstrated CO₂ adsorption capacities approximately three times higher than amine-based systems at ambient temperatures. Moreover, these materials released the captured CO₂ with minimal energy input, enhancing the overall energy efficiency of the process.
Economic analyses suggest that this LNG-integrated DAC approach could reduce the cost of capturing one metric ton of CO₂ to as low as $70, a significant decrease from the current estimates exceeding $200 per ton for conventional DAC methods. This cost reduction could make large-scale carbon capture more financially viable and accelerate its adoption in various industries.
An additional advantage of this technique is its potential applicability in coastal and humid regions, where traditional DAC systems face challenges due to high moisture levels. By utilizing existing LNG infrastructure, particularly at coastal terminals, this method could expand the geographical scope of effective carbon capture operations.
Professor Ryan Lively of Georgia Tech’s School of Chemical and Biomolecular Engineering emphasized the significance of this development, stating, “We’re showing that you can capture carbon at low costs using existing infrastructure and safe, low-cost materials.” Co-author Professor Matthew Realff added, “Many physisorbents that were previously dismissed for DAC suddenly become viable when you drop the temperature. This unlocks a whole new design space for carbon capture materials.”
The research team plans to continue refining the materials and system designs to ensure performance and durability at larger scales. Their goal is to facilitate the broader commercial adoption of this technology, contributing to global efforts to reduce atmospheric CO₂ levels and combat climate change.
This study represents a promising step toward more sustainable and cost-effective carbon capture solutions, highlighting the potential of innovative approaches that repurpose existing industrial processes for environmental benefit.