Salinity Gradient Energy Storage for Flexible RO Desalination
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Solution Overview
Problem
Current desalination technologies, particularly reverse osmosis (RO), are challenged by the intermittency of renewable energy sources, leading to increased reliance on fossil fuels, high energy consumption, and capital costs due to the inability to adapt to wide daily electricity price fluctuations and variable load demands.
Innovation Solution
A novel desalination system that splits the RO process into two steps, using batch reverse osmosis and pressure retarded osmosis, storing energy via reservoirs of different salinities to match energy availability and demand, allowing for demand response capabilities without significant capital cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reverse osmosis desalination is implemented to meet growing water demand, then clean water production capability is improved, but energy consumption and operational expenses increase significantly
Solution Approach 1:
The system performs preliminary energy storage during off-peak hours when electricity is cheaper and more abundant. Energy is stored by creating salinity gradients in reservoirs during low-demand periods, then this stored energy is utilized during peak hours to reduce the energy burden on the RO desalination process, effectively shifting energy consumption to more favorable times.
Solution Approach 2:
The system uses its own waste brine product as the energy storage medium. By utilizing the salinity difference between concentrated brine and feed water, the system creates an internal energy storage mechanism that serves the desalination process itself, eliminating the need for external energy storage infrastructure.
2Loss of energy
If renewable energy sources are coupled with reverse osmosis to decrease carbon footprint, then environmental sustainability is improved, but the system becomes sensitive to energy intermittency and price fluctuations
Solution Approach 1:
The system dynamically adjusts its operation based on real-time energy availability and price signals. When renewable energy is abundant and cheap, the system charges the energy storage reservoirs; when renewable energy is scarce or expensive, the system discharges stored energy to maintain RO operation, creating a flexible response to variable energy conditions.
Solution Approach 2:
The system changes its operational parameters based on energy conditions. By adjusting the salinity gradient storage levels and RO processing rates in response to energy price and availability changes, the system optimizes performance under varying renewable energy inputs while maintaining reliability.
3Stability of the object's composition
If conventional power generation systems are used to follow variable load, then energy supply stability is improved, but the system cannot adapt to wide daily electricity price fluctuations and intermittent renewable energy
Solution Approach 1:
The system employs periodic charging and discharging cycles of the energy storage reservoirs to match daily energy price patterns. Energy is stored during off-peak periods when prices are low and discharged during peak periods when prices are high, creating a periodic response that adapts to daily electricity price fluctuations while maintaining stable desalination operation.
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
Enables energy-efficient desalination by varying power requirements to match energy supply, reducing energy consumption by up to 25% and eliminating the need for expensive energy storage technologies, while maintaining desalination capacity.
Implementation Method 1
Reverse osmosis (RO) is the most energy-efficient and widespread technology for water desalination
Implementation Method 2
Energy is stored via reservoirs of different salinities
Implementation Method 3
pressure retarded osmosis
Data Source
AI summary
A method of desalinating water, including the steps of when electricity costs between a first predetermined price and a second predetermined price, fill water is pumped into a reverse osmosis desalination unit to yield desalinated permeate and saltwater having a first salinity, when electricity costs less than the first predetermined price, fill water is pumped into a reverse osmosis desalination unit to yield desalinated permeate and saltwater having a second salinity, and when electricity costs greater than the second predetermined price, pure water is flowed into a reverse osmosis unit to yield pressurized saltwater which is run through a turbine to generate electricity. The first salinity is lower than the second salinity.