Integrated Divalent Ion Precipitation in Bipolar Electrodialysis Reactors
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Solution Overview
Problem
Existing electrochemical ocean alkalinity enhancement (OAE) systems face high operational costs due to the energy consumption and maintenance requirements of bipolar electrodialysis devices (BPEDs), particularly in 3-chamber configurations, which hinder their widespread adoption as a cost-effective Negative Emissions Technology (NET) for reducing atmospheric CO2 and mitigating ocean acidification.
Innovation Solution
A method and system for removing divalent ions from seawater feedstock before electrochemical processing, using a chemical precipitator to increase pH and precipitate insoluble solids, followed by a 2-chamber ion exchange stack arrangement to reduce maintenance and energy costs, thereby enhancing the efficiency and reducing the levelized cost of producing base and acid substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bipolar electrodialysis devices (BPEDs) are used to generate base and acid products, then the ability to reduce atmospheric CO2 and mitigate ocean acidification is improved, but operational costs increase due to high energy consumption and maintenance requirements
Solution Approach 1:
The patent applies preliminary action by removing divalent ions from the feedstock solution before it enters the bipolar electrodialysis device. This pre-treatment step prevents scaling and fouling of membranes during operation, thereby reducing maintenance requirements and energy consumption while maintaining the device's effectiveness in CO2 reduction and ocean acidification mitigation
2Productivity
If 3-chamber BPED configuration is used, then base and acid product generation capability is improved, but maintenance frequency and energy consumption increase
Solution Approach 1:
The patent implements preliminary action by pre-removing divalent ions that cause scaling, thereby extending the duration between maintenance operations for the 3-chamber BPED configuration while preserving its high productivity for base and acid generation
3Device complexity
If divalent ions are not removed from feedstock, then system simplicity is maintained, but scaling and fouling of membranes occur increasing maintenance requirements
Solution Approach 1:
The patent applies segmentation by separating the ion removal process into two distinct stages: (1) a preliminary divalent ion removal step using precipitation or selective membranes, and (2) the main bipolar electrodialysis process. This segmentation prevents scaling in the BPED while maintaining overall system simplicity through modular design
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 proposed method significantly reduces operational costs by minimizing the need for frequent maintenance and energy consumption, making OAE systems more economically viable and effective in capturing atmospheric CO2 and mitigating ocean acidification.
Implementation Method 1
utilizing a portion of the base product to increase a pH level of the aqueous salt feedstock solution above a precipitation level of the divalent ions, thereby causing the precipitated divalent ions to form insoluble solids
Implementation Method 2
bipolar electrodialysis to generate base and/or acid products by electrochemically processing salt
Implementation Method 3
2-chamber ion exchange stack arrangement
Data Source
AI summary
A system utilizes an electrochemical reactor to convert salt into acid and base products. The salt is sourced from seawater, brine or another aqueous salt feedstock solution that typically also includes divalent ions. A small (slipstream) portion of the base product generated by the electrochemical reactor is fed back to a chemical precipitator where it is utilized to increase a pH level of the aqueous salt feedstock solution above a precipitation level of at least some the divalent ions, thereby causing precipitation of the divalent ions into insoluble solids. The insoluble solids are then filtered or otherwise separated/removed from the remaining supernatant solution (i.e., the aqueous salt/base solution formed by a mixture of the residual aqueous salt feedstock solution and base product). The supernatant solution is then supplied to the electrochemical reactor for conversion of its salt into additional acid and base product.