Breathe Easier: How a New Ammonia-Based System Could Revolutionize CO2 Capture
"Scientists are exploring an innovative approach to carbon capture that combines ammonia absorption with refrigeration, potentially making the process more efficient and eco-friendly."
The urgent need to address climate change has spurred intense research into carbon capture technologies. Among the promising alternatives to traditional methods is ammonia-based CO2 capture, which offers several advantages. Unlike conventional amine absorbents, ammonia is cost-effective, boasts a high CO2 removal capacity, doesn't degrade in the presence of oxygen or sulfur dioxide, requires less energy, and can capture multiple acid gases, potentially producing valuable byproducts.
However, ammonia-based systems have their challenges. The high volatility of ammonia can lead to its escape during absorption and desorption, increasing operational costs, causing secondary pollution, and even blocking pipelines and valves due to ammonia salt crystal formation. Mitigating this ammonia escape is crucial for the widespread adoption of this technology.
Now, researchers are exploring a novel approach: integrating ammonia-based CO2 capture with absorption refrigeration. This innovative combination aims to recover escaped ammonia during desorption and produce cooling, making the entire process more efficient and environmentally sound.
Ammonia-Based Capture and Process Tradeoffs
A 2021 comparative review describes one cost-reduction approach for aqueous-ammonia carbon capture: reducing the absorber column’s size for the ammonia–carbon dioxide reaction. A 2019 study evaluated ammonia as a solvent for post-combustion CO2 capture, focusing on the thermal performance and operation of the ammonia regeneration process. Separately, the Ammonia Energy Association’s 2025 methodology document covers ammonia production processes, including electrolytic hydrogen and applying carbon capture and storage to conventional production routes.
CCS History and the Road to Low-Emission Ammonia
A 2022 review says large-scale carbon capture and storage deployment is increasingly urgent on the path to net zero, but that deployment is significantly behind its expected contribution to emissions reduction. It argues that reviewing successful CCS practices in advanced countries can help inform other countries. A 2024 history article traces CCS origins and development and describes its contemporary role in environmental strategies. A separate account identifies Casale and other synthesis-loop designs as later industrial routes, and notes that present-day low-emission ammonia can retain ammonia synthesis while changing the hydrogen source through electrolysis or pairing conventional routes with carbon capture.
The Innovative Hybrid System: Capturing Carbon and Cooling the Planet
The proposed system combines CO2 capture with ammonia absorption refrigeration to recover any escaped ammonia during desorption. The process involves several key steps:
- Absorption: Cold flue gas meets an ammonia solvent, capturing CO2.
- Regeneration: The CO2-rich stream is heated in a generator, releasing CO2 and evaporating ammonia.
- Separation: The gas stream is condensed, separating water and then using a gas-liquid separator to isolate pure ammonia.
- Cooling: The separated liquid ammonia is throttled and evaporated, producing a cooling load.
- Re-absorption: The evaporated ammonia is reabsorbed, and the lean solvent cycles back to the absorber.
Recent Directions in Capture Research
A 2024 review of aqueous ammonia-based carbon capture (AAP) focuses on current developments and enhancement technologies intended to improve absorption-rate performance. Its abstract also proposes mass-transfer enhancement mechanisms for carbon capture using NH3. Separately, Nature’s carbon-capture research page reports that membrane-based CO2 separations are expanding into a broader range of applications, prompting development of new materials and separation mechanisms. A 2025 study describes an assessment of blue-ammonia production incorporating carbon capture and utilization through a life-cycle assessment approach.
Costs, Performance, and Scale Challenges
A March 2026 article argues that carbon capture faces high costs, poor results, and major scale challenges compared with renewables. A 2025 overview lists energy needs, leakage risks, high costs, public concerns, and performance among the limitations of CCS. Zero Carbon Analytics’ February 2024 briefing addresses both problems and potential for CCS, but the available description does not specify particular findings or figures.
The Future of Carbon Capture: A Chillingly Efficient Solution?
This novel ammonia-based CO2 capture process offers a promising route to reduce industrial emissions and generate cooling. By combining CO2 regeneration and ammonia evaporation, the system can effectively control ammonia escape and reduce regeneration energy consumption. Further research into absorption, crystallization, and the integration performance of CO2 regeneration and NH3 evaporation will pave the way for detailed experimental studies and real-world applications.