Device Extracts Water from the Air Using Nothing More than Gravity

A team of international researchers, led by KAUST Professor Qiaoqiang Gan, has designed a device that can potentially run with no electricity and extract water from the air with the help of nothing but gravity.

Water is perhaps Earth's most valuable resource. Despite covering 70% of our planet, freshwater, the water we use to drink, bathe, or irrigate our farmlands, is scarce. Only 3% of the world's water is freshwater, and two-thirds of that 3% dwells in frozen glaciers or is otherwise unavailable for use.

The result of water scarcity is a problem that is reflected all over the world. Close to 1.1 billion people lack access to water on a global scale. A total of 2.7 billion people in the world suffer from the scarcity of water for at least one month of the year.

Water shortage also leads to many other problems, such as inadequate sanitation, a problem for 2.4 billion people who get vulnerable and exposed to diseases like cholera and typhoid, and many other fatal diarrheal diseases.

The growing population and the ever-expanding demand for water have always been at loggerheads. The more populated our planet has become, the more stressed its water systems have become.

Rising pollution levels have taken a toll on the planet's rivers, lakes, and aquifers. What appears even more distressing is that over half of the world's wetlands have disappeared.

If the scientific community fails to evolve with time and offer solutions to combat the menace of disappearing water, our agriculture systems won't have enough water soon, leading to food insecurity and much more.

Fortunately, the scientific community is up to the challenge worldwide. Today, we shall discuss one such breakthrough solution in the coming segment and then delve deeper.

Device Extracts Water from the Air Using Nothing More than Gravity

A team of international researchers, led by KAUST Professor Qiaoqiang Gan, has designed a device that can potentially run with no electricity and extract water from the air with the help of nothing but gravity. The device, already free from the need for a costly energy supply, can be made with cheap and readily available materials.

The experiment paper, titled ‘Lubricated Surface in a Vertical Double-Sided Architecture for Radiative Cooling and Atmospheric Water Harvesting', seeks to make atmospheric water harvesting more efficient.

The water harvesting process improves significantly in radiative cooling. Radiative cooling works by significantly lowering condenser temperatures below ambient levels and making atmospheric water harvesting possible without additional energy.

One issue that radiative cooling systems face is the challenge of traditional sky-facing condensers having low cooling power density, and water droplets remaining pinned on the surface, requiring active condensate collection.

The research has proposed a solution to this problem: a lubricated surface (LS) coating—consisting of highly scalable polydimethylsiloxane elastomer lubricated with silicone oil applied on the condenser side in a vertical double-sided architecture.

The benefits of the design are several. For one, it effectively doubles the local cooling power.

Secondly, it eliminates contact-line pinning, enabling passive, gravity-driven collection of water. The result is pumped up AWH capacity from a 0 × 30 cm2 sample in outdoor environments, which was under no artificial flow of humidified air.

The passive water collection rate of the lubricated surface (LS) coating reached 21 g m−2 h−1, double that on a superhydrophobic surface, 10 g m−2 h−1. The performance was even better in an indoor setting, where the system could achieve a condensation rate of up to 87% of the theoretical limit with up to 90% of the total condensate passively collected.

Benefits of Atmospheric Water Harvesting Done Correctly

The atmosphere has six times more water than all the earth's rivers' freshwater combined. According to Professor Gan:

“This water can be collected by atmospheric water harvesting technologies.”

And when the process is done efficiently with the solution mentioned above, it becomes all the more profitable for its adopters. While elaborating on the benefits of the system, Professor Dan Daniel, one of the post-doctorates in Professor Gan's research group, had the following to say,

“The system doesn't consume any electricity, leading to energy savings. Moreover, it doesn't rely on any mechanical parts like compressors or fans, reducing the maintenance over traditional systems, leading to further savings.”

To Dan Daniel's observations, another post-doctorate of the team, Shakeel Ahmad, added:

“Our coating effectively eliminated pinning, enabling true passive water collection driven by water.”

Altogether, the system enhances the quality of atmospheric water harvesting by a significant margin, making AWH a true blue solution in this world of increasingly scarce water resources.

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Advances in Atmospheric Water Harvesting Systems

In October 2023, an article published in the scientific journal named Energy conducted a comprehensive review of techniques, performance, renewable energy solutions, and feasibility relating to the method of AWH. The review highlighted Atmospheric Water Harvesting as something that could be