Direct air carbon capture (DACC) is a technology designed to remove carbon dioxide (CO₂) directly from the atmosphere. It works by using specialized materials to absorb or filter CO₂ from the air, which is then released in a concentrated form for storage or use.
The Process of Direct Air Carbon Capture
DACC plants operate through a cyclical process that involves several key stages:
1. Air Intake and Capture
The first step involves moving large volumes of ambient air through the system.
- Air is drawn in through a fan located inside the collector. These large fans pull vast amounts of air into the DACC facility.
- Once sucked in from ambient air, it passes through a filter located inside the collector which traps the carbon dioxide particles. This "filter" is typically a sorbent or solvent material specifically designed to chemically bond with CO₂ molecules while allowing other air components (like nitrogen and oxygen) to pass through.
2. Releasing the Captured CO₂
Once the sorbent material is saturated with CO₂, or the solvent has absorbed enough CO₂, the system enters the regeneration phase.
- The CO₂ is released from the sorbent or solvent, often by applying heat or changing the pressure. This process requires energy.
- Releasing the CO₂ creates a concentrated stream of the gas, separate from the rest of the air.
3. Processing the CO₂
After being released, the concentrated CO₂ is ready for the next step.
- The CO₂ is typically compressed and purified.
- It is then transported to a storage site or prepared for utilization.
Key Components of a DACC System
DACC facilities rely on specific components to perform the capture process:
| Component | Function |
|---|---|
| Fans | Draw ambient air into the system. |
| Collectors | House the capture materials (sorbents/solvents). |
| Sorbents/Solvents | Chemically bind with CO₂ from the air. |
| Regeneration Unit | Releases CO₂ from the capture material. |
| Processing Unit | Compresses and purifies the released CO₂. |
What Happens to the Captured CO₂?
The concentrated CO₂ captured by DACC can be handled in two main ways:
- Geological Storage: The CO₂ is injected deep underground into suitable geological formations, such as depleted oil and gas reservoirs or saline aquifers, where it is permanently stored.
- Utilization (CCU): The CO₂ can be used as a feedstock in various industrial processes, such as creating synthetic fuels, manufacturing building materials, or carbonating beverages.
Why is DACC Important?
DACC is considered a potential tool in the fight against climate change because it can remove legacy CO₂ already in the atmosphere, which is something emissions reduction alone cannot achieve. It complements other climate solutions like renewable energy and carbon capture at point sources.
