Researchers from Stanford University and collaborating institutions have developed a more durable hydrogel that can harvest potable water from the atmosphere using only sunlight, potentially offering a new solution for water-scarce regions. The breakthrough addresses a longstanding challenge that has limited the practical use of atmospheric water-harvesting technologies: the rapid degradation of hydrogels used to absorb and release moisture.
Hydrogels are materials composed of absorbent polymers and salts that capture water vapor from the air during cooler periods and release it when heated. In previous field tests conducted in Chile’s Atacama Desert, one of the driest places on Earth, researchers demonstrated that a hydrogel made from lithium chloride and polyacrylamide could effectively collect moisture overnight. When heated by sunlight absorbed through a black-coated aluminum surface, the gel released water vapor that could be condensed and collected as drinking water. The material was capable of holding two to four times its weight in water.
Despite its effectiveness, the original hydrogel degraded after only about 30 operating cycles, creating concerns about both performance and water quality. Through extensive laboratory investigations, the researchers discovered that metal surfaces used in the system released ions that generated reactive radicals. These radicals attacked the polymer structure, causing the gel to break down and potentially contaminate collected water.
The team solved the problem by applying an anti-corrosion coating to the metal components. This simple modification dramatically improved durability. In testing, the hydrogel remained stable for more than eight months under extreme temperatures and successfully completed over 190 water-harvesting cycles without significant degradation.
The improved lifespan substantially enhances the technology’s economic potential. Researchers estimate that future systems could produce water for as little as one cent per liter, making atmospheric water harvesting competitive with conventional water sources. Current prototypes can generate up to two liters of water per day from a panel approximately the size of a bath towel, and researchers are working to increase output to five liters daily.
Because the system is solar-powered, operates off-grid, and requires minimal infrastructure, it could provide a sustainable source of drinking water for remote communities, disaster-response efforts, and arid regions where traditional water supplies are limited.