Passive and active water harvesting using metal-organic frameworks

Overview

Water harvesting using reticular chemistry offers an energy-efficient solution for generating potable water directly from atmospheric humidity. The technology leverages metal-organic frameworks (MOFs)—ultra-high porosity adsorbents precisely engineered at the molecular level to capture water vapor from air and release it as liquid water using minimal energy input. Designed for rooftop deployment at industrial facilities, these harvesters can operate passively using only ambient sunlight or actively by harnessing available waste heat sources to cycle the system repeatedly for increased water yield.

This approach addresses water scarcity by tapping an abundant and underutilized resource—atmospheric moisture—even in arid environments. Field validation in some of the driest locations in the United States has demonstrated reliable water capture at relative humidity levels far below those required by conventional atmospheric water generation technologies.

Technical specifications

• Core material: Metal-organic frameworks (MOFs), a class of reticular (precisely designed porous) materials with ultra-high surface area and tunable pore chemistry.
• Capture threshold: Harvests water at relative humidity as low as 7%, enabling operation in desert climates and across diverse geographic conditions.
• Passive operation: Requires no external energy input aside from ambient sunlight; water release is driven by solar heating.
• Active operation: Can be cycled multiple times using waste heat or low-grade thermal energy available at industrial sites, increasing total daily water yield.
• Pore environment design: MOF structures are engineered with a precise balance between hydrophobic and hydrophilic pore environments, allowing efficient water uptake from dry air and easy release with minimal energy.
• Validated performance metrics:
  • 200–300 mL of water collected per device in Arizona desert field trials.
  • 1.3 L of water per kilogram of MOF per day at 32% relative humidity and 27 °C using an electrically powered device.
  • 0.7–1.0 L of water per kilogram of MOF per day in the Mojave Desert at extreme conditions of 10% relative humidity and 27 °C.
• Deployment format: Roof-top-mounted devices suitable for integration with existing industrial infrastructure.

Technology readiness level

The technology has progressed beyond laboratory validation through multiple field-tested prototypes. Three MOF-based water harvesting devices have been built and evaluated in real-world desert environments, including Phoenix, Arizona and the Mojave Desert in California. Results confirm that MOFs can be designed to capture water under extremely low humidity conditions and release it with minimal energy input. The next phase of work involves building a demonstration passive harvester powered solely by ambient sunlight and collaborating with industrial partners to identify waste heat and cooling sources for an active, cyclable system. Feasibility analysis will balance water yield against energy costs to determine the optimal configuration for commercial-scale deployment.