Water-Harvesting Paint: A Cool Solution for Drought

Researchers at the University of Sydney and start-up Dewpoint Innovations have unveiled a groundbreaking nanoengineered polymer coating that can naturally cool buildings and extract water directly from the atmosphere without the need for energy input. This innovative technology has the potential to address global water scarcity issues and contribute to reducing the energy consumption of buildings.

The Science Behind the Innovation

A research team led by Professor Chiara Neto has developed a porous polymer coating that reflects up to 97% of sunlight and emits heat into the air, keeping surfaces up to 6° cooler than the surrounding environment even in direct sunlight. This cooling effect creates optimal conditions for atmospheric water vapor to condense into droplets on the cooler surface, similar to how steam condenses on a mirror.

Professor Neto emphasized the far-reaching implications of this technology, stating, “This advancement not only enhances the field of cool roof coatings but also introduces a sustainable, cost-effective, and decentralized approach to obtaining fresh water—a critical necessity in the face of climate change and escalating water scarcity.”

During a six-month outdoor study conducted on the roof of the Sydney Nanoscience Hub, the coating demonstrated the ability to collect dew for over 32% of the year, offering a reliable and predictable water supply even during rainless periods. Under optimal conditions, the coatings can harvest up to 390 mL of water per square meter daily, sufficient to meet the daily drinking requirements of an individual.

Environmental Benefits and Applications

Unlike conventional white paints, the porous coatings, composed of polyvinylidene fluoride-co-hexafluoropropene (PVDF-HFP), eliminate the need for UV-reflective pigments like titanium dioxide. Dr. Ming Chiu, the study’s lead author and Chief Technology Officer of Dewpoint Innovations, highlighted that the design achieves high reflectivity through its internal porous structure, ensuring durability without the environmental drawbacks associated with pigment-based coatings.

These innovative coatings can contribute to reducing urban heat island effects, lowering air-conditioning energy requirements, and providing climate-resilient water sources in regions facing heightened heat and water stress. Professor Neto emphasized that dew collection is not limited to humid climates, as dew can form even in arid regions where night-time humidity levels rise. This technology aims to supplement existing water sources by providing water where and when conventional sources are insufficient.

Commercialization and Future Prospects

Dewpoint Innovations is currently developing a water-based paint formulation that can be easily applied using standard rollers or sprayers to bring this innovative technology from the lab to rooftops. Perzaan Mehta, CEO of Dewpoint Innovations, expressed enthusiasm about partnering with the University of Sydney to introduce this breakthrough in passive atmospheric water harvesting through advanced paint-based coatings.

The successful commercial translation of this technology represents a significant step towards scalable, eco-friendly solutions for water harvesting and passive cooling, with potential applications in various sectors such as built environment, agriculture, remote communities, and urban infrastructure.