Indirect air CO₂ capture and refinement based on OTEC seawater outgassing

Area of Science:

• Environmental Science
• Chemical Engineering
• Oceanography

Background:

• Atmospheric CO2 dissolves in seawater, following Henry's law.
• Open-cycle ocean thermal energy conversion (OC-OTEC) utilizes large volumes of seawater for electricity generation.
• CO2 and other gases are extracted during OC-OTEC's vacuum compression process.

Purpose of the Study:

• To propose a low-cost method for capturing and purifying CO2 from ocean water indirectly from the atmosphere.
• To evaluate the potential of utilizing waste gas streams from OC-OTEC for CO2 capture.
• To estimate the economic feasibility of the proposed CO2 capture and purification process.

Main Methods:

• Leveraging the CO2 dissolved in seawater within the OC-OTEC process.
• Refining non-condensable gases (containing CO2) from OC-OTEC using a water absorption process.
• Calculating levelized CO2 capture and purification costs based on literature and process design.

Main Results:

• Non-condensable gases from OC-OTEC's cold water intake contain up to 14% CO2.
• A water absorption process can refine these gases to 80-90% CO2 purity.
• Estimated levelized CO2 capture and purification costs range from 15 to 35 euros per ton.

Conclusions:

• The proposed method offers a cost-effective approach to CO2 capture and purification.
• Waste gas streams from OC-OTEC represent a viable source for CO2 recovery.
• This technology has the potential to contribute to carbon mitigation strategies.