Palm device drinks Death Valley's air

A portable water harvester, no larger than two hands, managed to extract potable water from the arid air of Death Valley National Park in California, relying solely on sunlight and utilizing no battery, plug, or moving parts. The research, revealed by a Times of India report, was spearheaded by Omar Yaghi, a University of California, Berkeley chemist who received the 2025 Nobel Prize in Chemistry, along with Susumu Kitagawa and Richard Robson, for their work on metal-organic frameworks, or MOFs, which drive the technology.

The harvester utilizes MOF-303, an aluminum-based metal-organic framework, an intricate crystalline substance refined over years by Yaghi's team. This material soaks up water molecules from the air during the cooler nights in Death Valley, when humidity is typically higher, and subsequently releases them as heat from the sun warms it during the day. The vapor condenses onto a cooler surface within the device, dripping into a container.

In the test, the device managed to produce up to 210 grams of water per kilogram of MOF-303 in a 24-hour cycle, the highest output ever recorded at that site, according to the release. However, the same device in Berkeley, where the air is milder and more humid, only yielded up to 285 grams per kilogram per day, though its average daily output dropped on some days.

The findings were published in a 2023 Nature Water paper by Woochul Song, Zhiling Zheng, Ali Alawadhi, and Yaghi, and they mark roughly double the output of an earlier version of the harvester.

This was a continuation of Yaghi's earlier work, with the Death Valley device being a refinement of a 2017 collaboration between Yaghi's team and mechanical engineers at MIT, which used a zirconium-based material called MOF-801. The initial study, published in Science, demonstrated that a solar-driven harvester could generate meaningful water even in low humidity conditions of 20 to 30 percent, producing about 2.8 liters of water per kilogram of MOF daily.

The report added that replacing MOF-801, which costs $160 per kilogram, with MOF-303, which costs only $3 per kilogram, significantly reduced the harvester's cost of production. The higher yield, however, came from MOF-303's chemistry rather than its lower cost.

Desert air poses a greater challenge compared to typical air humidity since dehumidifiers only cool air below its dew point to pull water. Desert air is trickier because, when humidity falls below 20 percent, the dew point can drop below freezing, requiring a far greater energy input for condensation to occur. MOFs overcome this issue because their pores absorb water molecules even at very low humidity, and heat alone is sufficient to release them.