Electrodialysis Current and Flow Control for Variable Renewable Power
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Solution Overview
Problem
Existing desalination technologies face challenges with high energy consumption, brine production, and reliance on energy storage, making them unsuitable for resource-constrained regions and developing economies, particularly in arid areas where groundwater salinization is prevalent.
Innovation Solution
An electrodialysis system controller that matches power usage to available renewable energy sources, using a cascade control system with inner current and outer flow control loops to maximize desalination rate while minimizing energy storage needs, by dynamically adjusting current and fluid flow rates based on real-time power availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional desalination technologies (reverse osmosis) are used, then desalination can be achieved, but energy consumption is high and brine production is large
Solution Approach 1:
The system dynamically changes operating parameters (current, flow rate) based on available power to optimize the balance between energy consumption and desalination productivity. By adjusting parameters in real-time rather than operating at fixed conditions, the system achieves high efficiency across varying power availability.
Solution Approach 2:
The patent implements a dynamic control system that continuously adapts operating conditions to match available renewable power. The controller adjusts current and flow rate dynamically, allowing the system to operate efficiently whether power is abundant or limited, thereby resolving the contradiction between energy loss and productivity.
2Use of energy by moving object
If renewable energy sources are used for desalination, then operating expenses are reduced, but power availability varies erratically
Solution Approach 1:
The system employs feedback control where the controller continuously monitors available power and adjusts operating parameters accordingly. This closed-loop control ensures reliable operation by adapting to power fluctuations in real-time, maintaining desalination efficiency despite variable renewable energy input.
Solution Approach 2:
The dynamic adjustment of current and flow rate based on real-time power availability allows the system to reliably operate with erratic renewable energy sources. The controller's ability to rapidly respond to power changes ensures continuous, reliable desalination performance.
3Reliability
If batteries are added to ensure consistent power supply, then power reliability is improved, but system complexity and capital expenditure increase
Solution Approach 1:
The patent extracts or removes the battery component from the system by implementing a controller that directly manages power fluctuations through dynamic parameter adjustment. This approach achieves power reliability without adding the complexity and cost of energy storage hardware.
Solution Approach 2:
The system serves its own power regulation needs through intelligent control algorithms that balance desalination performance with available power. The controller acts as a self-regulating mechanism, eliminating the need for external battery systems while maintaining reliable operation.
4Productivity
If higher current is applied to increase desalination rate, then productivity is improved, but water splitting occurs which reduces efficiency
Solution Approach 1:
The controller uses feedback from flow rate and concentration measurements to adjust current levels, maintaining operation near the optimal point where high productivity is achieved without excessive water splitting. This real-time monitoring and adjustment prevents energy waste while maximizing desalination rate.
Solution Approach 2:
The system dynamically changes current and flow rate parameters to maintain optimal operating conditions. By coordinating parameter changes rather than independently increasing current, the system achieves high productivity while avoiding the inefficiencies of water splitting.
5Loss of energy
If flow rate is increased to improve heat dissipation and prevent water splitting, then energy efficiency is improved, but power consumption increases
Solution Approach 1:
The system coordinates changes in both flow rate and current as coupled parameters rather than independent variables. By simultaneously optimizing both parameters based on available power and operational conditions, the system achieves efficient heat dissipation and prevents water splitting without unnecessarily increasing power consumption.
Solution Approach 2:
The dynamic control system adjusts flow rate and current in coordination with each other and with available power levels. This coupled dynamic adjustment ensures that flow rate increases only when necessary and when power is available, optimizing the balance between energy efficiency and power 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
This approach increases desalination efficiency, reduces energy storage requirements, and enables sustainable, low-operating expense desalination, particularly in regions with variable renewable energy sources, thereby enhancing the adoption of desalination systems in developing economies and large-scale industrial applications.
Implementation Method 1
One current desalination technology is electrodialysis reversal (EDR) in which ions move across ion exchange membranes. When these ion exchange membranes are arranged in an alternating manner, channels of diluate and concentrate are formed between them.
Implementation Method 2
A production rate of desalinated water depends on the voltage applied to the membranes and a rate at which water flows through the channels.
Implementation Method 3
there are nontrivial constraints on the flow rate and voltage applied, which avoid water splitting
Data Source
AI summary
An electrodialysis system controller is configured to be coupled to a power supply, and powered devices that include a pump, and an electrodialysis unit. The controller receives inputs including an input indicative of a flow rate through the electrodialysis unit, an input indicative of a concentration level of fluid in the electrodialysis unit, and an input indicative of a power differential (e.g., indicating a degree to which a power usage by the powered devices differs from available power of the power source), and provides outputs for controlling the powered devices, including an output for causing a variable current level to be applied in the electrodialysis unit, and an output for causing a variable fluid flow rate through the electrodialysis unit. The controller is configured to match the power usage to the available power, for example, to keep the power differential as small as possible, while maximizing the theoretical desalination rate of the electrodialysis system.