A collaboration of researchers from multiple universities in the US has successfully demonstrated the use of adsorbent fins to harvest water from the air. This innovative approach is more efficient than previous water harvesting technologies and could help secure water supplies in dry and arid regions, according to a press release.

As the planet warms and climatic conditions become more extreme, access to clean water is expected to trouble millions of people. Traditionally, our water supplies have been dependent on the availability of local water bodies. However, advances in technology now make it possible to extract water from the air.

Estimates suggest that trillions of liters of fresh water are available in the Earth’s atmosphere as water vapor. The challenge lies in finding an efficient method to convert this water vapor into liquid form for local use.

In areas where fog or dew is common, it is relatively easier to cool the air and access fresh water. Researchers at the Massachusetts Institute of Technology, the University of Tennessee Knoxville, and the Georgia Institute of Technology have designed a new humidity harvester specifically for drier areas.

Previous efforts have shown that harvesting humidity in relatively dry regions requires special materials. Various materials, ranging from temperature-responsive hydrogels to metal-organic frameworks, have been used for this purpose. Crystalline aluminosilicates, also known as zeolites, are particularly effective at absorbing moisture from the air, even when humidity is low. The extraction of water is relatively simple, requiring only the application of heat.

The US-based researchers suggest that for this technology to be deployed in the real world, the setup needs to be small, compact, and ideally connected to a device that produces heat as a by-product. To design their compact water harvester, the researchers used a novel fin design for water adsorption. They created this fin structure by sandwiching thin copper sheets between copper foam coated in a zeolite material.

To demonstrate their technology, the team built a harvester device with ten small fins placed next to each other, no wider than two millimeters apart. The setup was placed on a base copper plate and tested in an environment with 10 percent relative humidity, similar to desert air.

The team found that the fins were saturated with water within an hour. They could harvest the water by increasing the temperature to 363 degrees Fahrenheit (183 degrees Celsius). Extrapolating these 24 collection-release cycles, the researchers found that the device could collect up to 1.3 liters of water per day in an environment with 30 percent relative humidity. This is up to five times more than the water that can be harvested from similarly built devices, according to the press release.

The researchers suggest integrating the device into existing infrastructure, such as buildings or vehicles that produce waste heat, to develop a cost-effective solution for harvesting fresh water. Such a system would be highly beneficial in arid regions, as it can quicken the pace of water harvesting.

By Impact Lab