Direct CO2 Air Capture Using Acid-Base Ion-Exchange and Low-Grade Heat

Scientists believe anthropogenic CO2 emissions are the primary driver of global climate change, leading to many adverse outcomes for humanity. Technologies reducing current CO2 emissions and lowering atmospheric CO2 are needed to prevent future climate-induced destruction. The technology to scrub exhaust gases from fossil power plants is well-established, and fossil plants and natural gas, ethanol, oil, and fertilizer producers have implemented technology to capture emissions from exhaust streams. New technologies to scrub CO2 directly from ambient air are under development. Known as direct air capture (DAC), this technology is challenging due to the low CO2 concentration in air, resulting in high required CO2 absorber airflow rates. In addition, large quantities of high-temperature heat are typically required to regenerate the CO2 sorbents. Advanced Cooling Technologies, Inc. (ACT) and Lehigh University (LU) propose the development of a novel DAC system that can utilize a low-grade heat source (industrial waste heat or geothermal) to regenerate the CO2 scrubbing medium. The proposed system can utilize waste heat at temperatures as low as 80°C and has minimal electrical loads. This system uses commonly-available CO2-selective adsorbent materials, which reduces costs and helps alleviate supply constraints. The system design and layout allow it to scale easily and maintain a small footprint. The project team has successfully demonstrated this CO2 capture technology at the bench scale showing that the CO2 selective materials adsorbed CO2 very well even at the low CO2 concentrations of ambient air. ACT and LU will model, design, fabricate, and experimentally test a complete lab-scale DAC system during the proposed Phase I program. System modeling will be used to design the lab-scale and future full-scale systems, and experimental test results will be compared against DAC systems deployed around the world today. The findings of the Phase I work will allow the team to refine the proposed DAC capture system design to maximize CO2 capture per volume of adsorbent and energy consumption per mass of CO2 captured. The technical advantages of the proposed DAC technology allow for its use at both industrial scales and the much smaller grassroots level. The proposed concept would be easily adopted at an industrial scale since most plants are familiar with similar chemical systems for water treatment. Waste heat in the 100°C range is readily available at industrial plants and other applications such as geothermal sources and agricultural operations such as grain drying. The team also envisions a highly-distributed deployment for their system with small-scale installations across local communities at schools, churches, non-government organizations, and wastewater treatment plants.