A salt-rejecting floating solar still for low-cost desalination

Abstract

Although desalination technologies have been widely adopted as a means to produce freshwater, many of them require large installations and access to advanced infrastructure. Recently, floating structures for solar evaporation have been proposed, employing the concept of interfacial solar heat localization as a high-efficiency approach to desalination. However, the challenge remains to prevent salt accumulation while simultaneously maintaining heat localization. This paper presents an experimental demonstration of a salt-rejecting evaporation structure that can operate continuously under sunlight to generate clean vapor while floating in a saline body of water such as an ocean. The evaporation structure is coupled with a low-cost polymer film condensation cover to produce freshwater at a rate of 2.5 L m⁻² day⁻¹, enough to satisfy individual drinking needs. The entire system's material cost is $3 m⁻² – over an order of magnitude lower than conventional solar stills, does not require energy infrastructure, and can provide cheap drinking water to water-stressed and disaster-stricken communities.