Watts and Drops: Co-Scheduling Power and Water in Desalination Plants

2025-09-23

AI Summary

This study addresses the operational optimization of renewable energy–driven hybrid thermal–membrane desalination plants, aiming to maximize net revenue through coordinated water–electricity scheduling. To account for wind–solar generation volatility, two-way electricity market participation, multi-technology coupling, grid interactions, and forecast uncertainty, we formulate a stochastic programming model. Theoretical analysis reveals a threshold-type monotonic relationship between freshwater production and renewable power generation, enabling derivation of an analytically tractable optimal scheduling policy. This policy jointly ensures freshwater supply stability and responsive participation in electricity markets. Under guaranteed water security constraints, it significantly improves on-site renewable energy utilization and plant profitability. The resulting interpretable, implementable coordination framework advances green-power–driven desalination systems.

Technology Category

• Planning, Routing, and Scheduling: Mixed Discrete/Continuous Planning
• Search and Optimization: Mixed Discrete/Continuous Search
• Constraint Satisfaction and Optimization: Mixed Discrete/Continuous Optimization

Application Category

• Economics, Online Markets and Human Computation: Cost models of using LLMs in production systems
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

We develop a mathematical framework to jointly schedule water and electricity in a profit-maximizing renewable colocated water desalination plant that integrates both thermal and membrane based technologies. The price-taking desalination plant sells desalinated water to a water utility at a given price and engages in bidirectional electricity transactions with the grid, purchasing or selling power based on its net electricity demand. We show that the optimal scheduling policy depends on the plant's internal renewable generation and follows a simple threshold structure. Under the optimal policy, thermal based water output decreases monotonically with renewable output, while membrane based water output increases monotonically. We characterize the structure and intuition behind the threshold policy and examine key special properties.

Problem

• Jointly scheduling water and electricity in renewable desalination plants
• Optimizing bidirectional electricity transactions with the power grid
• Developing threshold-based policy for thermal and membrane technologies

Innovation

• Mathematical framework for joint water-electricity scheduling
• Bidirectional electricity transactions with the power grid
• Threshold-based policy coordinating thermal and membrane technologies