Passive high-yield seawater desalination at below one sun by modular and low-cost distillation

TL;DR

This paper introduces a passive, modular, low-cost solar distillation system for seawater desalination that achieves high yields at less than one sun, promising sustainable freshwater solutions for remote and emergency use.

Contribution

The authors develop a novel passive distiller design that doubles the previous yield at less than one sun and requires no mechanical parts, enhancing affordability and scalability.

Findings

Achieved nearly 3 L/m²/h distillate flow rate at <1 sun in lab and outdoor tests.

Distiller design doubles the yield of recent passive devices.

Theoretical models indicate potential for further doubling of flow rate.

Abstract

Although seawater is abundant, desalination is energy-intensive and expensive. Using the sun as an energy source is attractive for desalinating seawater; however, the performance of state-of-the-art passive devices is unsatisfactory when operated at less than one sun ($<$ $1$ $kW$ $m^{-2}$). Here, we present a completely passive, modular, and low-cost solar thermal distiller for seawater desalination. Each distillation stage is made of two opposed hydrophilic layers separated by a hydrophobic microporous membrane, and it does not require further mechanical ancillaries. Under realistic laboratory and outdoor conditions, we obtained a distillate flow rate of almost $3$ $L$ $m^{-2}$ $h^{-1}$ from seawater at less than one sun - twice the yield of recent passive device reported in the literature. In perspective, theoretical modelling suggests that the distiller has the potential to further doubling the peak flow rate observed in the current experiments. This layout can satisfy freshwater needs in isolated and impoverished communities, as well as realize self-sufficient floating installations or provide freshwater in emergency conditions.