Dual-Pathway Ocean CO2 Capture System
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Solution Overview
Problem
Current methods for capturing CO2 from ocean water are costly and inefficient, particularly due to high oceanwater intake and pretreatment costs, and the limited scalability of land-based systems, which makes it challenging to meet the target of < $100/t-CO2 for large-scale carbon removal.
Innovation Solution
A dual-pathway system that uses an off-shore, floating platform to process ocean water through an acid-base generator, electrodialyzer, and membrane contactors to generate both acidified and alkaline streams for CO2 capture, minimizing oceanwater intake and energy consumption by operating at high current densities and using catalyst-bonded membrane contactors for efficient CO2 removal from slightly acidified water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional CO2 capture methods are used from ocean water, then CO2 removal is achieved, but the cost is high and scalability is limited
Solution Approach 1:
The system divides CO2 capture into two separate pathways: an acidic pathway using HCl to convert bicarbonate to CO2, and an alkaline pathway using NaOH to precipitate carbonate minerals. This segmentation allows each pathway to be optimized independently, reducing overall cost and improving scalability compared to conventional single-method approaches.
Solution Approach 2:
The electrodialyzer with bipolar membranes serves multiple functions: it generates both HCl and NaOH from seawater, acts as a purification apparatus, and provides the chemical basis for both acidic and alkaline CO2 removal pathways. This multi-functionality reduces system complexity and cost while enabling scalable deployment.
2Productivity
If large volumes of ocean water are processed, then CO2 capture capacity increases, but energy consumption and processing costs increase
Solution Approach 1:
The system changes the pH parameter of seawater through controlled acidification (adding HCl) and alkalization (adding NaOH) to drive CO2 release and carbonate precipitation. By adjusting pH rather than processing large volumes of water, the system achieves high CO2 capture capacity with reduced energy consumption for water handling.
Solution Approach 2:
Instead of processing entire volumes of seawater through energy-intensive filtration and treatment, the system takes a small portion, modifies its chemical properties (pH), and uses this modified portion to treat larger volumes by injection. This copying approach dramatically reduces energy consumption while maintaining high capture capacity.
3Productivity
If traditional electrodialysis is used to generate acid and base, then CO2 removal is achieved, but the system requires excessive purification and operates at low efficiency
Solution Approach 1:
The bipolar membrane electrodialyzer generates both HCl and NaOH simultaneously from seawater through electrochemical reactions at the bipolar membranes. The system is self-sufficient, producing its own acid and base reagents without requiring external purification infrastructure. This self-service capability reduces device complexity and improves operational efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system significantly reduces costs by minimizing oceanwater processing and energy use, achieving efficient CO2 capture and meeting the < $100/t-CO2 target, while maintaining environmental standards by releasing decarbonized water back into the ocean with similar pH and salinity.
Implementation Method 1
at least one electrodialyzer in fluid communication with the purification apparatus and incorporated a bipolar membrane configured to convert the feedstock of NaCl into a HCl feedstock and a NaOH feedstock
Implementation Method 2
electrodialyzer...configured to convert the feedstock of NaCl into a HCl feedstock and a NaOH feedstock
Implementation Method 3
an acidification element in fluid communication with the HCl feedstock and configured to produce an acidified oceanwater feedstock...converts the bicarbonate in the ocean water to CO2
Implementation Method 4
a catalyst-bonded membrane contactor in fluid communication with the acidification element and a vacuum system to extract gaseous CO2 from the acidified oceanwater feedstock
Implementation Method 5
an alkaline CO2 removal system in fluid communication with a source of fluid entrained CO2 and in further fluid communication with the NaOH feedstock and configured to produce a CO2 lean effluent and a carbonate
Data Source
AI summary
A dual-pathway system for CO2 capture in both acidified and basified streams is provided. The system may be embodied in an off-shore stand-alone facility to allow for the operation of oceanic CO2 capture to be more efficient and cost effective. Systems maintain high environmental standards by containing all intermediate acidic and alkaline solutions in a closed system so that the effluent discharged back into the ocean is at the similar pH and salinity as the feed oceanwater, with only CO2 removed. Acid and base produced by an electrodialyzer unit is used to achieve oceanwater decarbonization via gaseous CO2 removal and solid CaCO3 precipitates removal. The system is configured to require the processing of a very small fraction of the total oceanwater intake for the acid-base generation process.