As the need to reduce atmospheric CO₂ levels becomes increasingly urgent, CO₂ removal technologies have emerged as a promising solution. Among these, industrial direct air capture (DAC) systems leveraging electrochemistry are gaining significant attention for their ability to capture CO₂ directly from ambient air while potentially producing valuable byproducts like like hydrogen, syngas, acids, and cement.
Based on our research into DAC companies, we categorize these electrochemistry-based technologies into three main types:
- Electrodialysis-based DAC
- Electrolysis-based DAC
- Electroswing-based DAC
Bipolar membrane electrodialysis (BMED) is a key technology within electrodialysis-based DAC systems. It produces acidic (e.g., HCl, H₂SO₄) and alkaline (e.g., NaOH) solutions from saline or brine. The alkaline solution serves as an efficient liquid sorbent for capturing atmospheric CO₂. Consequently, BMED has been integrated into DAC systems for this purpose. However, bipolar membranes present challenges, including high costs and significant maintenance requirements. Additionally, BMED typically exhibits high energy consumption. To address these limitations, emerging bipolar membrane-free electrodialysis technologies are being developed as a more cost-effective alternative for DAC.
In contrast to electrodialysis, water electrolysis offers the added benefit of producing valuable chemicals such as hydrogen (H₂). Electrolysis-based DAC systems capture atmospheric CO₂ while simultaneously generating byproducts like H₂ or syngas, making them attractive for applications where co-production of fuels or chemicals is desired.
Electroswing technology represents an innovative approach to DAC. It employs electrochemical redox reactions to adsorb and desorb CO₂ efficiently. This cutting-edge method has the potential to revolutionize climate change mitigation efforts.
In this work, we will analyze and present these industrial electrochemistry-based DAC technologies in detail.
(This article contains 14 diagrams and 2920 words.)