Ocean Alkalinity Enhancement Using Bipolar Electrodialysis
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Solution Overview
Problem
Current negative emissions technologies (NETs) for reducing atmospheric CO2 and mitigating ocean acidification face challenges such as economic sustainability, measurability, permanence, additionality, toxicity, safety, and scalability, particularly with Mineral Ocean Alkalinity Enhancement approaches.
Innovation Solution
An electrochemical ocean alkalinity enhancement (OAE) system that generates a base solution containing fully dissolved NaOH molecules and supplies it to the ocean, increasing seawater alkalinity and enhancing its ability to absorb atmospheric CO2. The system includes a base-generating device using bipolar electrodialysis and a control circuit that ensures safe and efficient operation, including monitoring low/zero-carbon electricity availability and environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solid alkaline substances (e.g., crushed minerals such as olivine or lime) are added to seawater to enhance the ocean's ability to absorb atmospheric CO2, then the ocean's carbon sink function is enhanced, but dissolution kinetics issues arise and the process is slow and inefficient
Solution Approach 1:
The patent changes the physical state of the alkaline substance from solid to fully dissolved molecular form (NaOH). This parameter change eliminates dissolution kinetics limitations and enables rapid, complete mixing with seawater, dramatically increasing the rate at which ocean alkalinity can be enhanced and CO2 can be absorbed.
Solution Approach 2:
The patent replaces mechanical crushing and gradual dissolution processes with an electrochemical system (bipolar electrodialysis) that directly generates fully dissolved NaOH molecules. This substitution of the underlying mechanism eliminates the time-consuming dissolution step entirely while maintaining the beneficial effect of increased ocean alkalinity.
2Quantity of substance
If Mineral Ocean Alkalinity Enhancement approaches are deployed at scale, then significant CO2 removal capacity is achieved, but economic sustainability and scalability challenges arise
Solution Approach 1:
The bipolar electrodialysis system generates both the base (NaOH) and acid (HCl) substances needed for ocean alkalinity enhancement from seawater itself, without requiring external inputs of chemical precursors or energy-intensive importation of solid minerals. This self-service capability improves economic sustainability and simplifies scaling.
Solution Approach 2:
The patent transforms the input material from solid minerals requiring crushing and dissolution to fully dissolved molecular NaOH generated in-situ. This parameter change enables precise control of alkalinity addition rates and simplifies the logistics of deployment and scaling across different ocean locations.
3Productivity
If base substance is supplied to increase seawater pH rapidly, then CO2 absorption capacity is enhanced, but safety risks to marine life increase
Solution Approach 1:
The patent incorporates a control circuit that continuously monitors seawater pH and other parameters, using feedback control to adjust the rate of base substance supply. This ensures that alkalinity enhancement proceeds at optimal rates that maximize CO2 absorption capacity while maintaining pH levels within safety thresholds for marine life.
Solution Approach 2:
The patent changes the form of base substance from solid particles with unpredictable dissolution rates to fully dissolved molecular NaOH with controlled, uniform release. This parameter change enables precise dosing and rapid equilibration, allowing safe, controlled enhancement of seawater pH without creating localized hotspots that could harm marine organisms.
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 OAE system effectively reduces atmospheric CO2 and mitigates ocean acidification by increasing ocean alkalinity, avoiding dissolution kinetics issues of conventional approaches, and ensuring long-term permanence of CO2 capture, with the potential to scale to significant CO2 removal levels.
Implementation Method 1
a base-generating device that electrochemically processes an externally supplied feedstock (saline) solution to generate a base solution comprising fully dissolved NaOH molecules
Implementation Method 2
supplying the ocean alkalinity product to ocean seawater at a designated outfall location, whereby the base substance diffuses (disperses) into the surrounding seawater
Data Source
AI summary
An ocean alkalinity enhancement (OAE) system that reduces atmospheric CO2 and mitigates ocean acidification by electrochemically processing feedstock solution (e.g., seawater or brine) to generate an alkalinity product that is then supplied to the ocean. The OAE system includes a base-generating device and a control circuit disposed within a modular system housing deployed near a salt feedstock. The base-generating device (e.g., a bipolar electrodialysis (BPED) system) generates a base substance that is then tested and processed (e.g., mixed/diluted with processed feedstock solution, seawater or another saltwater solution and/or reacted with CO2) to generate the ocean alkalinity product. The control circuit controls the base-generating device such that the alkalinity product is supplied to the ocean only when supplying the alkalinity product will not endanger sea life. Modified BPED systems include features that facilitate autonomous system operations including enhanced maintenance cycle operations and a reduced reliance on external fresh water sources.