CO2 mitigation via capture and chemical conversion in seawater.

Area of Science:

• Environmental Science
• Chemical Engineering
• Oceanography

Background:

• Rising atmospheric carbon dioxide (CO2) levels drive climate change and ocean acidification.
• Existing CO2 capture technologies can be energy-intensive and costly.
• Natural processes like mineral weathering sequester CO2 over geological timescales.

Purpose of the Study:

• To evaluate the efficacy of a lab-scale seawater/mineral carbonate gas scrubber for CO2 capture.
• To assess the stability of captured carbon in solution.
• To explore the potential of this method for point-source CO2 mitigation and ocean carbon sequestration.

Main Methods:

• Utilized a lab-scale gas scrubber with seawater and mineral carbonate.
• Simulated flue gas streams containing CO2 were passed through the scrubber.
• Analyzed the capture efficiency and the form of the sequestered carbon (calcium bicarbonate).
• Assessed carbon retention in solution after equilibration with air.

Main Results:

• Achieved up to 97% CO2 removal from simulated flue gas at ambient conditions.
• A significant portion of captured carbon was converted to dissolved calcium bicarbonate.
• Up to 85% of captured carbon remained in solution after air equilibration, indicating stability.
• The process generates an alkaline solution.

Conclusions:

• Seawater/mineral carbonate scrubbing is a potentially simple and effective method for point-source CO2 capture.
• This low-tech approach is suitable for retrofitting power plants and deployment in developing nations.
• The resulting alkaline solution could benefit marine ecosystems and utilize ocean's carbon sequestration potential.
• The method accelerates natural CO2 sequestration processes.