Carbon capture is a technology designed to reduce emissions of carbon dioxide (CO₂), the main greenhouse gas responsible for climate change. It aims to prevent CO₂ generated by human activities, such as burning fossil fuels, from reaching the atmosphere.

There are several carbon capture technologies, which differ according to the time at which the CO₂ is captured in the process of generating emissions and the medium from which it is extracted. Here is a summary of the main ones:

1. Capture in industrial or power plants

These technologies are applied directly at the emitting sources, such as factories or power plants.

a) Post-combustion capture

  • How it works: CO₂ is extracted from the waste gases after combustion.
  • Common technology: Use of chemical solvents, such as amines, which absorb CO₂.
  • Advantage: Can be retrofitted to existing plants.
  • Disadvantage: High energy consumption to regenerate the solvents.

b) Pre-combustion capture

  • How it works: The fuel (such as natural gas or coal) is converted into a mixture of hydrogen and CO₂ before burning.
  • The CO₂ is separated before combustion.
  • Used in: Gasification plants.
  • Advantage: More efficient than post-combustion in some cases.

c) Oxy-combustion

  • How it works: The fuel is burned with pure oxygen instead of air, producing a stream of gases with high CO₂ and water vapour.
  • The vapour condenses and the CO₂ is easily captured.
  • Advantage: Purer CO₂ stream, easier to capture.
  • Disadvantage: Costly to produce pure oxygen.

2. Direct Air Capture (DAC)

  • How it works: Extracts CO₂ directly from ambient air using chemical filters or thermal processes.
  • Advantage: Can be located anywhere.
  • Disadvantage: Much more expensive and less efficient than capturing at source.

3. Enhanced Natural Capture Technologies (Bioenergy with Carbon Capture and Storage – BECCS)

  • How it works: Plants that absorb CO₂ are grown, used as biomass to generate energy, and the CO₂ generated is captured and stored.
  • Advantage: Can generate negative emissions.
  • Disadvantage: Requires a lot of land and water.

4. Advanced capture materials

  • Examples:
    • MOFs (Metal-Organic Frameworks): Porous materials that absorb CO₂.
    • Membranes: selectively filter CO₂.
    • Solid sorbents: Materials that react chemically with CO₂.