How to Capture Carbon Dioxide from the Air<br />Assist. Prof. Malik Mustafa Mohammed<br /><br /> Direct Air Capture (DAC) Technology <br />The most prominent method for capturing CO₂ directly from ambient air is Direct Air Capture (DAC), a technology that employs chemical or physical processes to extract carbon dioxide. Here’s a detailed breakdown of how it works, based on current innovations: <br /> 1. Core Mechanism: Sorbent-Based Capture <br />DAC systems use sorbents (chemicals or materials) to selectively bind with CO₂ molecules in the air. Two primary approaches dominate: <br />- Liquid Sorbents: <br /> - Alkaline solutions (e.g., potassium hydroxide or amine-based liquids) react with CO₂ to form stable compounds. <br /> - Air is passed through the liquid, where CO₂ is absorbed- <br />Solid Sorbents: <br /> - Porous materials like zeolites, metal-organic frameworks (MOFs), or amine-functionalized resins trap CO₂ via physical adsorption or chemical binding. <br /> - These sorbents are often cooled to enhance CO₂ uptake and heated later to release concentrated CO₂.<br /> 2. Key Steps in the DAC Process <br />A typical DAC system follows three stages: <br />1. Capture: <br /> - Ambient air is drawn into the system using fans or blowers. <br /> - CO₂ interacts with the sorbent, either dissolving in liquid or adhering to solid surfaces.<br />2. Processing: <br /> - For liquid systems: The CO₂-rich solution is heated to release pure CO₂ gas (regenerating the sorbent for reuse). <br /> For solid systems, the material is heated or depressurized to desorb CO₂, which is then collected.<br />3. Storage/Utilization: <br /> - Captured CO₂ is compressed and transported for underground storage (sequestration) or used in industrial processes (e.g., synthetic fuels, concrete).<br /> 4. Energy Requirements <br />- DAC systems are energy-intensive, primarily for heating sorbents (to release CO₂) and powering air-moving equipment. <br />To ensure sustainability, renewable energy sources (e.g., solar, wind) are critical for powering DAC plants, thereby minimizing the carbon footprint of the process.<br />5. Emerging Innovations <br />- Thermochemical DAC: <br /> - Uses high-temperature heat (e.g., from concentrated solar power) to drive redox reactions in materials like ceria, splitting CO₂ from air without liquid solvents. <br />- Modular Systems: <br /> - Compact, scalable units are being developed for decentralized deployment in urban or industrial areas.<br /> Challenges and Considerations <br />- Cost: Current DAC technologies require significant energy input, making them expensive compared to point-source carbon capture (which targets concentrated CO₂ emissions from factories or power plants).<br />- Scalability: Widespread deployment depends on advances in sorbent materials and the integration of renewable energy. <br /><br />"Al-Mustaqbal University – The No. 1 Private University in Iraq"<br /><br /><br />