How atmospheric water harvesting can be scaled

Water scarcity is a huge global issue. More than 2 billion people lack access to safe drinking water—a situation set to worsen due to climate change, which fuels longer and more severe droughts. As reservoirs shrink, groundwater dries up and rainy seasons become more erratic. Some believe one answer to this crisis lies in the reservoirs of moisture in our skies.

The question is: How close are we to turning air into a dependable water source, and when does it make sense to do so? An article published in Joule explores how atmospheric water harvesting could move from laboratory prototypes to commercial systems by linking thermodynamic limits with a survey of existing products and customer needs. The analysis highlights the gap between what physics makes possible and what the market demands.

Energy paid

Atmospheric water harvesting follows two main routes. Condensation systems cool air to its dew point and collect liquid water. Sorption systems capture vapor in a sorbent and release it with heat. The study builds first-principles models for both routes and calculates the minimum energy required across climates and heat source temperatures. That baseline frames realistic targets for device performance.

Condensation is straightforward but sensitive to climate. At high humidity, conventional refrigeration hardware can deliver continuous, high-volume output. As air gets drier, the energy penalty rises. More input goes to sensible heat, which cools the entire air stream, rather than to the latent heat of condensation. At about 30% relative humidity, the sensible share can approach half of the total, which lowers efficiency and raises cost. In very dry air, dew points can fall below 0°C, frost can form on coils and both heat transfer and water production drop.

Sorption changes the balance. Because the sorbent selects water molecules from the air, the sensible heat fraction is typically lower, often under 30% in dry conditions in the authors’ calculations. Practical performance still depends on a suitable heat source for regeneration and on tight coupling between the sorbent and the heat and mass flows inside the device.

The market scan covers more than 100 participants, their reported energy use and daily output, and financing milestones. Condensation products dominate shipments today, supported by mature heat-pump supply chains and dehumidifier experience. Several vendors list units above 1,000 L per day, yet measured energy use often sits well above the theoretical floor.

The gap stems from multiple irreversibilities and from air-conditioner-style layouts that under-recover heat and moisture and mismatch components. Sorption products are earlier in scale up. Many devices produce under 10 L per day and use non-uniform energy accounting, but investment and technical progress are fast, with strong links to universities and materials advances such as metal-organic frameworks, graphene, and salt-based composites.

How to close the gap to commercialization

A unified platform offers a path to scale. We propose using a heat pump as a common energy backbone. The cold side supplies either direct condensation or enhanced adsorption during uptake, and the hot side drives desorption. A four-way valve alternates beds between adsorption and regeneration for near-continuous operation. Efficiency can improve with multistage heat pumps, tighter sorbent heat-exchanger integration, recovery of condensation heat and selective use of ambient energy.

Economics complete the picture. The analysis uses levelized cost of water and payback period and compares distributed AWH with trucking as distance grows. Longer haul distances improve AWH competitiveness. Priority use cases include emergency and military response, mobile and vehicle-mounted supply, urban bottled-water and beverage replacement, distributed supply for high-rise or modular buildings, and supplemental capacity alongside seawater desalination in some regions.

Progress depends on scenario-first design. Select a target climate, a target customer and a target energy source, then tune materials and systems to that triangle. Standardized energy metrics enable fair comparisons. Closed heat and moisture loops reduce losses and move performance closer to thermodynamic limits. A heat-pump backbone that serves both condensation and sorption on one platform can shorten the path from prototypes to market.

The message we hope readers take away is that better materials or bigger compressors alone will not carry AWH to scale. What closes the gap is alignment: climate conditions with service requirements and energy supply measured against transparent thermodynamic limits and reported on standardized energy bases. If the community coalesces around that yardstick—and if builders embrace heat-pump-centered, climate-adaptive platforms—we believe AWH can move quickly from impressive demonstrations to bankable infrastructure.

This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate.

He Shan is a research fellow at the National University of Singapore (NUS). He earned his joint Ph.D. degree in 2025 under the supervision of Prof. Ruzhu Wang at Shanghai Jiao Tong University (SJTU) and NUS. Prior to that, he received his B.S. degree from Chongqing University in 2019. His research focuses on hydrogel-based atmospheric water harvesting and energy management.