Solar-Powered Water Purification

Water scarcity caused by pollution in the wake of natural disasters or supply system damage is a severe threat to modern society and a severe challenge to emergency response/rescue agencies. In Texas, boil water notices associated with extreme weather events have highlighted the need to provide short-term, point-of-use technologies. In other cities, concerns associated with Pb and other contaminants have driven people to consider alternative point-of-use options. Thermal processes such as vapor compression and multiple-effect distillation are enticing, but they require significant infrastructure that incorporates energy on energy recycling to make them competitive with reverse osmosis. Reverse osmosis technologies that use membranes to purify water have several limitations including high cost, energy inefficiency, potential fouling, and significant wastewater discharge. Solar-powered water purification is one of the most promising potential technologies to enable household production of distilled water at low cost and high efficiency.1,2 However, the core step of solar water purification, i.e. vapor generation, is highly energy-intensive. The mismatch of diffuse solar flux and the energy required for water vaporization (i.e. phase change enthalpy) fundamentally hinder the efficiency.