Assessing global drinking water potential from electricity-free solar water evaporation device

Abstract

Universal and equitable access to affordable safely managed drinking water (SMDW) is a significant challenge and is highlighted by the United Nations’ Sustainable Development Goals-6.1. However, SMDW coverage by 2030 is estimated to reach only 81% of the global population. Solar water evaporation (SWE) represents one potential method to ensure decentralized water purification, but its potential for addressing the global SMDW challenge remains unclear. We use a condensation-enhanced strategy and develop a physics-guided machine learning model for assessing the global potential of SWE technology to meet SMDW demand for unserved populations without external electricity input. We find that a condensation-enhanced SWE device (1 m²) can supply enough drinking water (2.5 L day⁻¹) to 95.8% of the population lacking SMDW. SWE can help fulfill universal SMDW coverage by 2030 with an annual cost of 10.4 billion U.S. dollars, saving 66.7% of the current investment and fulfilling the SDG-6.1 goal.

Solar water evaporation is regarded as a promising toolset for decentralized drinking water purification. This study predicts the global drinking water supply potential via solar water evaporation, highlighting where and how to promote solar evaporation devices to fulfill the United Nations Sustainable Development Goal 6.1 with reasonable costs.