Conventional amine scrubbing for carbon capture uses heat energy to release CO₂ during the desorption process. High-temperature treatment causes chemical changes in the amines, leading to the formation and release of toxic and carcinogenic compounds such as nitrosamines. The amine regeneration process therefore has a significant negative environmental impact. It also poses serious hazards to workers and the public in the vicinity of post-combustion capture plants that operate based on amine absorption and regeneration. Despite these drawbacks, amine-based CO₂ capture technology remains versatile and widely applied.

In recent years, electrochemical carbon capture methods have emerged as promising alternatives. These methods use electricityrather than heat or high pressureto capture and release CO₂. They often operate at room temperature and can be powered by renewable energy sources, making them attractive alternatives to conventional amine scrubbing.

Recent research efforts have led to continuous improvements in the desorption step of amine scrubbing technology. As a result, Electrochemically Mediated Amine Regeneration (EMAR) was developed to use electrical energy to release CO₂ captured from post-combustion flue gas, thereby avoiding the need for thermal regeneration of amines.

The steps involved in EMAR are

• CO₂ is absorbed from flue gas using a liquid amine (similar to traditional systems).
• Instead of using heat to release CO₂, an electrochemical cell changes the chemistry of the amine.
• A metal ion (commonly copper) binds to the amine when voltage is applied, forcing CO₂ to be released.
• Reversing the voltage regenerates the amine for reuse.

CO2-loaded amine → CO2 + Regenerated amine

So how it works?

1. CO₂ absorption

   An amine solvent (often ethylenediamine or similar amines) absorbs CO₂ from a gas stream, forming carbamate/bicarbonate species.

   2RNH2 + CO2 ⇌ RNHCOO− + RNH3+
2. Electrochemical generation of metal ions

   Instead of heating the solvent in a stripper column, an electrochemical cell is used. A metal ion, commonly copper (Cu²⁺) is generated at the anode and selectively binds to the amine more strongly than CO₂ does.

   Cu(s) → Cu2+ + 2e−
3. CO₂ release

   When the metal complexes with the carbamate, the CO₂ is displaced. Amine now prefers binding Cu²⁺ instead of CO₂, the carbamate breaks down and CO2released as a concentrated gas stream.

   RNHCOO− + RNH3+ + Cu2+ → [Cu(RNH2)2]2+ + CO2
4. Amine recovery

   At the cathode, the metal ions are reduced back tometallic copper and amine is regenerated.

   [Cu(RNH2)2]2+ + 2e− → Cu(s) + 2RNH2

   Aqueous amine + CuSO₄ will act as the electrolyte.Electricity drives a reversible metal–amine coordination cycle that replaces the thermal stripping step used in conventional amine regeneration.

Core benefits of EMAR

• Much lower energy consumption (~1–2 GJ/ton CO₂ equivalent vs ~3–4 GJ/ton CO₂ for conventional amine carbon capture)
• EMAR runs primarily on electricity rather than steam
• Smaller plant footprint
• Lower amine degradation
• Higher operational flexibility