Pneumatic tube inspired DAC system could make carbon capture more affordable

A seemingly ordinary errand to deposit a check at a bank drive-through turned into a remarkable breakthrough reminiscent of stories from books and movies. Researchers at Georgia Tech were working on a novel method to simplify traditional direct air capture (DAC) systems. Their innovative approach involved using the natural flow of ambient wind to draw air across a new type of coated carbon fiber, effectively capturing CO2 without the need for loud fans commonly used in existing systems. Additionally, the carbon fiber strands could be efficiently heated to release the captured carbon dioxide with minimal heat loss, increasing overall efficiency.

However, the researchers faced a challenge in deploying these sorbent-coated carbon fibers for optimal effectiveness. It was during a trip to the bank, where they encountered the old-fashioned pneumatic tubes used to transport documents, that inspiration struck. Ryan Lively, a professor at Georgia Tech’s School of Chemical and Biomolecular Engineering, had a “light bulb moment” and realized that the fibers could be placed in a canister similar to those used in bank teller tubes.

Taking inspiration from the pneumatic tubes, the team incorporated the design into their system and began testing. They discovered that their approach could produce carbon dioxide of sufficient purity for underground sequestration while eliminating many of the significant upfront costs associated with traditional DAC systems. The details of their design and methodology were published in the journal Joule on June 12.

Won Hee Lee, the first author of the paper and a former postdoctoral scholar in Lively’s lab, expressed the significance of their work, stating, “This work not only conceptualized a new generation of DAC systems but also demonstrated practical operations of our invention to some extent.” Lee further emphasized that scaling up the module was the next crucial step, considering that all the system’s components are commercially available and fabrication is relatively straightforward.

The team has conducted a theoretical scale-up of their system, using experimental data to project the economic feasibility of a practical implementation. Their analysis revealed that their system could capture CO2 at a cost of $150 to $200 per ton, significantly lower than the projected costs of other commercial systems, which range from $300 to $600 per ton.

A simpler approach

Researchers at Georgia Tech had an “aha” moment while on a simple errand to deposit a check at a bank drive-through. They had been working on simplifying direct air capture (DAC) systems by using ambient wind flow to draw air across sorbent-coated carbon fibers, eliminating the need for loud fans. They struggled with deployment until they saw the pneumatic tubes used in the bank drive-through and realized they could place the fibers in a similar canister. With the pneumatic tube-inspired modules, they tested their system and successfully produced carbon dioxide with sufficient purity for underground sequestration, while reducing upfront costs. They published their findings in the journal Joule.

The team plans to scale up the module, as all the system’s components are commercially available and fabrication is relatively easy. The projected economics of the practical system suggest that it could capture CO2 for $150 to $200 per ton, much lower than the estimated costs of other commercial systems. The researchers’ design also offers several advancements, including inside-out heating of carbon fiber strands for fast and even heat distribution, as well as a simplified system architecture with fewer components.

The carbon fiber strands used in the system have suitable properties, are readily available, sustainably manufactured, and cost-effective. The team aims to improve the purity of the captured carbon dioxide to 99% for productive reuses such as making chemicals or fuels. They are working with the Georgia Tech Research Institute to refine and automate the system and plan to install a test system on a campus building.

Overall, their innovative approach combining ambient wind flow and inside-out heating has the potential to make direct air capture cheaper, more efficient, and environmentally friendly, contributing to efforts in addressing climate change.

Source: Georgia Institute of Technology

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