As global water shortages worsen, engineers at Rice University have developed a new solar-powered desalination system that could revolutionize access to clean drinking water. Known as Solar Thermal Resonant Energy Exchange Desalination (STREED), the system provides a decentralized, low-maintenance alternative to traditional desalination technologies and is designed to function efficiently with or without continuous sunlight.

Desalination—the process of removing salt and impurities from water—is widely used in coastal regions, but current systems rely heavily on expensive infrastructure and filtration membranes that are prone to fouling and degradation. These setups are often ill-suited for remote or off-grid communities, where access to power and maintenance resources is limited.

STREED addresses these issues by using solar energy to drive a heat exchange process between two fluid streams: one carrying heated saline water and the other air. This method draws from principles seen in oscillating systems like pendulums or electrical circuits, where energy naturally cycles between states at resonant frequencies. By allowing heat to oscillate efficiently between water and air, STREED is able to conserve energy and continue producing fresh water even during periods of low sunlight.

Unlike reverse osmosis systems, which rely on delicate membranes and struggle with highly saline water, STREED uses air as a natural separator. Salty or polluted water flows through a heated channel, where it evaporates. Adjacent air captures the water vapor, which then condenses in a separate chamber, leaving salts and impurities behind. This membrane-free approach reduces maintenance needs and increases durability.

The system is built from non-degradable, inexpensive materials and can be produced using low-cost 3D printing, making it well-suited for scalable production and deployment in a wide range of settings. It is designed to be modular and adaptable, particularly for use in remote, off-grid areas where conventional systems are not feasible.

Initial field tests in San Marcos, Texas, showed that the prototype could produce up to 0.75 liters of fresh water per hour. Simulations using solar data from various U.S. cities—including cloudy locations like Portland, Oregon, and sunnier areas like Albuquerque, New Mexico—demonstrated that STREED maintains high energy-to-water efficiency regardless of solar intensity, outperforming static-flow systems by 77% during a typical week.

In addition to its innovative design, STREED features an internal control system that adjusts fluid flow based on sunlight levels. This ensures optimal performance throughout the day without requiring external energy storage, further reducing complexity and cost.

The research, published in Nature Water in April 2025, highlights the potential of STREED to provide sustainable, off-grid freshwater solutions. Funded by agencies including the National Science Foundation, the U.S. Army, and the Heritage Medical Research Institute, this development reflects a growing effort to make advanced water purification accessible and reliable in the face of a global water crisis.

By Impact Lab