Capillary-driven solar-thermal water desalination using a porous selective absorber

Abstract

The desalination of seawater has the potential to address the increasing demand for potable water. Specifically, solar-thermal water desalination can generate clean water without relying significantly on fossil energy. However, the inefficient use of solar energy often limits the overall performance, which affects the rate, efficiency, and feasibility of large-scale implementation. This study shows the use of a spectrally-selective nanomaterial as an absorber to improve the performance of solar-thermal desalination. This material is designed to maximize the absorption of sunlight and minimize the loss of energy by thermal emission, which allows higher throughput and efficiencies compared to broadband absorbers. In this study, we show a 10% enhancement in the evaporation rate of water by using a selective absorber compared to a graphite absorber. We demonstrate a scalable approach involving the use of wicking materials interfaced with the spectrally-selective absorber for the desalination of saline water to get 73% of overall efficiency using a solar flux of one sun. This demonstration of an inexpensive strategy for producing clean water can potentially transform the field of solar-thermal desalination to address the rising demand for water.