Environment: Tapping into the potential of harvesting water from the air

Solar-powered atmospheric water harvesting could provide safe drinking water for approximately 1 billion people, a global assessment modelled on hypothetical devices suggests. The findings, published in Nature, could inform designs for emerging and future harvesting technology.

Approximately 2.2 billion people lack access to safe drinking water worldwide, with the highest populations located in sub-Saharan Africa, South Asia and Latin America. Atmospheric water harvesting devices have been suggested as solutions to water shortages and work in two ways. Passive water harvesting devices rely solely on weather conditions to harvest pre-condensed dew or fog. Active devices, by contrast, may employ solar energy to either condense the water following harvesting at night when humidity is higher, or work on a continuous cycle, which reduces the size of device needed. However, questions have been raised over their performance and the global potential of the devices has not been analysed.

Jackson Lord, Philipp Schmaelzle, Ashley Thomas, and colleagues present a geospatial tool for assessing the potential of atmospheric water harvesting devices to provide safe drinking water. The tool incorporates global patterns of humidity, air temperature and solar radiation and is based on hypothetical solar-powered water harvesting devices with 1–2 m2 solar collection areas. Results show that strong sunlight and humidity above 30% do in fact sufficiently coincide and support producing an average of five litres of water per day via continuous daytime operation. Deployed widely, such devices may have the potential to provide safe drinking water for approximately 1 billion people who live in these climate conditions. The authors also compared these results with the potential of existing devices and indicate that these targets are possible with emerging technologies.

The analysis is focused on safe drinking water and does not assess water for other uses such as irrigation, sanitation or cooking. The authors suggest with continued technological development their projections could be met and could inform future design to maximize global impact.