UC Berkeley

Seawater desalination is one of the most resilient approaches for obtaining water. However, conventional desalination technologies are also some of the most energy-intensive water treatment processes. For this reason, seawater desalination is often viewed as a last resort, and is generally only an option for large urban centers—where the costs can be spread across densely populated districts. With limited access to reliable power grids, technical and managerial expertise, essential supply chains, and financial resources, smaller communities are often the most vulnerable to the impacts of climate change.

Interfacial solar vapor generation (ISVG) is a phenomenon observed in nano-enabled materials to efficiently vaporize water at extremely high efficiencies when exposed to sunlight. Traditionally, these are porous, light-absorbing materials that float at the air-water interface where evaporation normally takes place. When irradiated by sunlight, these materials absorb that light, convert that light into heat, transfer that heat to water in its pores, and accelerate the rate of evaporation. As a result, these 2D-ISVG materials can achieve an evaporative flux of 2.00 kg m-2 h-1, which is nearly 200% higher than natural rates. While impressive, this rate is still too low for many practical applications. To increase this rate, we have developed a 3D-ISVG material that utilizes capillary action to wick water onto additional surfaces for evaporation. This enhancement has allowed us to achieve an evaporative flux of 34.7 kg m-2 h-1. Given this higher productivity, we have begun evaluating the feasibility of developing 3D-ISVG into a sustainable desalination technology for small-island communities. Specifically, we have been working with Bungin Island in Indonesia to understand how contextual factors should inform the design and implementation of this technology as a means of providing sustainable water access in a climate-impacted future.