Direct Air Capture & Biogenic Removal

While point-source carbon capture offers a solution to prevent new CO₂ emissions from entering the atmosphere, it does not address the existing high concentration of CO₂ already present. To tackle this, a separate and increasingly popular technology known as Direct Air Capture (DAC) has emerged. DAC provides a corrective approach by actively removing CO₂ from the atmosphere, making it especially valuable for offsetting historical emissions and addressing sectors that are particularly difficult to decarbonize, such as transportation.

One key advantage of DAC is its geographic flexibility, it is not tied to a specific emission source and can be deployed in locations with abundant renewable energy, which is crucial given the technology’s current limitation: high energy consumption. DAC typically requires around 6–9 GJ of energy per ton of CO₂ captured [1], largely due to the low concentration of CO₂ in ambient air compared to industrial flue gases.

DAC systems commonly rely on two main approaches: chemical absorption (Liquid DAC or L-DAC) and solid adsorption (Solid DAC or S-DAC). In L-DAC, CO₂ is captured using aqueous basic solutions, such as potassium hydroxide, and then released through regeneration processes operating at high temperatures (300–900 °C) or electrolysis. In contrast, S-DAC uses solid adsorbents that work under ambient or low-pressure conditions and release CO₂ when heated to moderate temperatures (80–120 °C). Emerging technologies like Electro Swing Adsorption use electrochemical cells where solid electrodes adsorb CO₂ when negatively charged and release it when the charge is reversed. According to International Energy Agency [1] , as of now, 27 DAC facilities have been commissioned across the world. Most are small-scale demonstration plants, with only a few operating under commercial agreements for CO₂ sale or storage. It is projected that DAC deployment could reach approximately 3 Mt captured CO₂ by 2030.