Effective Precipitate Cleaning with a Reversible Flow Cell Sustains Stable Energy Intensity for Oceanic CO₂ Removal.

Area of Science:

• Environmental Science
• Electrochemistry
• Chemical Engineering

Background:

• Oceans absorb significant anthropogenic CO2 emissions, leading to acidification.
• Efficient and scalable CO2 removal technologies are critical for climate change mitigation.
• Electrochemical methods offer potential for direct ocean carbon capture.

Purpose of the Study:

• To experimentally demonstrate a novel CO2 removal method from ocean water.
• To optimize flow channel design for enhanced mass transfer and reduced pressure drop.
• To validate the self-cleaning capabilities of the proposed system.

Main Methods:

• Utilizing a combination of H2 and redox salt looping in electrochemical flow cells to induce pH swings.
• Employing model-driven design optimization for 3-D printed electrolyte flow channels.
• Investigating the effect of a ridged flow channel with angled fins on boundary layer thickness and pressure drop.
• Assessing electrode surface fouling removal over multiple acidification/basification cycles.

Main Results:

• A ridged flow channel design reduced redox salt concentration boundary layer thickness by up to 35% with a pressure drop under 415 Pa.
• Demonstrated 86% removal of electrode fouling over 4 cycles, maintaining constant electrochemical energy intensity.
• Successful lab-scale, proof-of-concept validation of the CO2 removal and self-cleaning process.

Conclusions:

• The novel method shows promise for efficient oceanic carbon removal and utilization.
• The optimized flow channel design and intrinsic cleaning capabilities enhance system scalability and reduce downtime.
• Further research can build upon these findings to improve large-scale ocean carbon capture systems.