Desalination via Concentration Difference Energy
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Solution Overview
Problem
Current desalination methods, such as reverse osmosis, multiple effect distillation, and electrodialysis, face challenges with high energy consumption, performance issues with warm seawater, and inefficiencies due to voltage gradients and ion migration, limiting their effectiveness in providing freshwater for populations lacking access.
Innovation Solution
A desalination apparatus and method utilizing a plurality of drive cells with ion exchange membranes to generate a drive voltage from concentration differences between diluent and concentrate solutions, allowing for energy-efficient desalination without external power sources, reducing ion migration losses, and maintaining performance across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse osmosis is used for desalination, then desalination can be achieved, but energy consumption increases and performance deteriorates when temperature exceeds 30°C
Solution Approach 1:
The patent replaces the mechanical pressure-driven reverse osmosis system with an electrochemical system using ion exchange membranes and applied voltage. This substitution eliminates the mechanical compression requirements and allows desalination to proceed effectively at higher temperatures where reverse osmosis fails, while reducing overall energy consumption through more efficient ion transport mechanisms.
Solution Approach 2:
The patent changes the operating parameters by applying voltage across ion exchange membranes rather than applying mechanical pressure. This parameter change enables the system to maintain effective desalination performance at temperatures above 30°C, overcoming the temperature limitation of reverse osmosis while consuming less energy through the electrochemical mechanism.
2Reliability
If electrodialysis is used for desalination, then desalination can be achieved, but energy consumption increases and ion migration losses occur
Solution Approach 1:
The patent extracts and eliminates the need for external DC power sources and rectifiers by utilizing the natural concentration difference between feed and product streams. The system harnesses the inherent electrochemical potential from the saltwater concentration gradient to drive ion transport through ion exchange membranes, removing the energy loss associated with external power conversion and reduction.
Solution Approach 2:
The system performs self-service by using the saltwater concentration difference itself as the energy source. The feed solution's higher salt concentration naturally provides the electrochemical potential needed to drive desalination, eliminating the need for external energy input and associated losses from power conversion hardware.
3Reliability
If electrodialysis is used for desalination, then desalination can be achieved, but voltage gradients cause ion migration through manifolding reducing efficiency
Solution Approach 1:
The patent segments the ion transport process into discrete compartments using alternating cation-exchange and anion-exchange membranes. This segmentation creates a structured pathway that prevents voltage gradients from causing unwanted ion migration through manifolding, as each membrane layer selectively transports ions in controlled directions through the segmented structure.
Solution Approach 2:
The patent introduces ion exchange membranes as intermediary elements between the feed solution and product solution. These membranes act as selective mediators that facilitate controlled ion transport while blocking the pathways that would otherwise allow voltage-gradient-driven ion migration through the manifolding structure, thereby maintaining desalination efficiency.
4Reliability
If multiple effect distillation is used for desalination, then desalination can be achieved, but thermal energy consumption increases
Solution Approach 1:
The patent replaces the thermal-based distillation process with an electrochemical process using ion exchange membranes and applied voltage. This substitution eliminates the need for continuous thermal energy input to drive evaporation and condensation cycles, achieving desalination through electrochemical ion transport that consumes significantly less energy.
Solution Approach 2:
The patent avoids relying on phase transitions (evaporation and condensation) that consume large amounts of thermal energy. Instead, it uses ion exchange membranes to directly separate ions from water through electrochemical potential differences, eliminating the need for phase change cycles and associated thermal energy consumption.
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 solution enables energy-efficient desalination of saltwater using readily accessible low-temperature energy, reducing capital costs, and improving efficiency by minimizing ion migration and pre-treatment requirements, while maintaining performance with warm seawater.
Implementation Method 1
a plurality of drive cells for generating a drive voltage, each drive cell having a diluent chamber for containing a diluent of a first ionic concentration, a concentrate chamber for containing a concentrate of a second ionic concentration that is greater than the first ionic concentration, one of a cation or anion exchange membrane forming a shared boundary between and in ionic communication with the diluent and concentrate chambers
Implementation Method 2
utilizing the energy difference that exists between two solutions of different solute concentrations that are separated by an ion exchange membrane
Data Source
AI summary
A method and apparatus for desalinating saltwater using concentration difference energy is disclosed. In order to desalinate saltwater that is contained within a product chamber, a drive cell is used to generate a drive voltage. The product chamber has a desalination voltage such that when a sufficient voltage is applied to the product chamber, anions and cations migrate out of the product chamber, thereby desalinating the water. The sufficient voltage, which includes the drive voltage and which is equal to or greater than the desalination voltage, is applied to the product chamber, consequently effecting desalination. Beneficially, concentration difference energy can be generated using a concentrated solution, which can be generated using, for example, solar energy.