As atmospheric CO₂ levels need to be reduced, direct air capture (DAC) technologies have emerged as a promising solution. Among these, industrial DAC systems based on liquid sorbents are gaining significant attention for their potential to remove CO₂ directly from ambient air at scale.
Liquid sorbent-based DAC technologies utilize chemical processes to selectively extract CO₂ from the atmosphere. These systems typically employ aqueous solutions of strong bases, such as potassium hydroxide (KOH), sodium hydroxide (NaOH), or calcium hydroxide (Ca(OH)₂), to selectively and efficiently absorb CO₂ from ambient air. As air passes through these liquid solvents, CO₂ is absorbed, forming carbonate or bicarbonate compounds.
However, the methods of regenerating aqueous alkaline solutions make the existing industrial DAC technologies distinct. The liquid sorbent regeneration also determines how atmospheric CO₂ is sequestered, which is one of the most important concerns in DAC technologies. Here, we analyze our research results of DAC companies and categorize their technologies according to the methods for sequestering atmospheric CO₂:
- The concentrated stream of captured atmospheric CO₂ is stored or rescued.
- Atmospheric CO₂ is sequestered in valuable byproducts.
- Atmospheric CO₂ is sequestered in seawater.
We will present and describe these industrial DAC technologies through process flow diagrams.
(This article contains 4 diagrams and 1814 words.)