Global Potential for Harvesting Drinking Water from Air using Solar Energy

Abstract Access to safely managed drinking water (SMDW) remains a global challenge affecting 2.2 billion people [1,2]. Atmospheric Water Harvesting (AWH) can accelerate progress through decentralized production of liquid water from air [3]. A solar-driven device capable of active daytime operation can unlock design advantages through continuous cycling [4,5] and could be sized to household scale, though lower daytime humidity raises concerns about widespread suitability [6–8]. However, no methodological analysis has been conducted to characterize the global potential of daytime AWH [9] despite the favorable climatic conditions of low and middle-income countries (LMICs) in the tropical regions where two-thirds of people without SMDW services live [2]. Here we present a computing toolset built with Google Earth Engine to calculate the global potential of solar-driven AWH operating in continuous mode. By mapping time-averaged, contemporaneous occurrence of incident solar energy and available water vapor using a climate timeseries and official estimates of the geographic distribution of water service globally, we show that a significant portion of the world’s population without SMDW reside in a climate suitable for a device to serve their daily drinking water requirements. A device functional to relative humidity 30% can serve 1 billion in need by running 4-5 h/day above 600 W/m2, operational parameters which have been approached experimentally in recent prototypes using novel sorbents [10–17]. Steep gradients of AWH suitability in the Sahel of Africa indicate high sensitivity of design criteria to market serviceability. This global assessment of solar-driven AWH, unlocked by accessible high-performance geospatial computing [18] and climate data assimilated at high spatio-temporal resolution, can enable household-scale device innovation and accelerate the progress towards global goals.