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Direct air capture is difficult due to the low concentration of carbon dioxide (CO2), which requires large amounts of air to be circulated, where dust particles, water and other gases interfere with the capture process. Regenerating material to release the CO2 is costly, so it requires low energy input to make capture technologies cost effective. This technology is a porous carbon fiber mat for which an electrical current allows easy desorption of captured carbon, allowing for configuration in air handling units without pressure drop issues. Carbon fiber mats, however, have minimal chemical functionality that allow for carbon capture, and thus must be post-modified for desirable synthetic procedures. Plasma techniques applied to the mat surface changes the chemical functional groups which makes this possible for proper post-chemical functionalization. 

Description

Technologies for direct air capture have several challenges. They require large amounts of air, where dust, water and other gases can interfere with the process. Also, regeneration is costly and it requires high energy input as a result. The technology here uses modified plasma treated porous carbon fiber for carbon capture, which in turn can utilize electrical resistance heating for desorption. The plasma changes the chemical functionality on the surface of the fibers, which then are tethered with sorbents, minimizing leaching of sorbents that normally occur with untethered sorbents on surfaces. The plasma conditions oxidize specific functional groups of the porous carbon fibers giving ideal linkages for post-synthetic functionalization of carbon active sites, such as amines, for capture. An electrical current – provided by non-fossil fuel sources – allows easy desorption of captured carbon, instead of direct thermal treatment. Thermal treatment requires heating of materials and their containers which is expensive, and cost intensive. It also has implications of having to remove materials from their containment to be heat treated, thus an added expense in downtime and labor. At the end of the process, recycling of carbon is possible with application of electrical current through resistive heating, and it requires less energy and thus lower cost. This technology becomes useful as HVAC filters that are less costly, energy efficient, and that help to capture carbon from the air as units are already in place. 

Applications and Industries

• HVAC industry 
• Commercial and residential construction 

Benefits

• Overcome pressure drop 
• Low-cost, less labor intensive, energy efficient 
• Recyclable CO2 
• Use of renewable electricity 

Contact 

To learn more about this technology, email partnerships@ornl.gov or call 865-574-1051.