Water purification and electricity production can be achieved simultaneously in a single device using sunlight, reports a paper in Nature Communications. The findings may one day help to mitigate the shortage of energy and clean water in arid and semiarid regions.
The increasing demand for energy and clean water globally represents a challenge for sustainable development. Electricity production can require large amounts of water, and, in turn water purification plants need electricity to operate. Sunlight can be used as a sustainable and renewable energy source to fuel both solar cells and water purification devices, but both technologies have limited energy and cost efficiencies.
Peng Wang and colleagues combined two existing solar-driven technologies - photovoltaics and multi-stage membrane distillation - to simultaneously produce electricity and clean water. Membrane distillation is an advanced solar-driven process requiring relatively low temperatures to efficiently evaporate and collect water. The authors designed a three-stage membrane distillation unit mounted on the rear side of a photovoltaic panel so that the heat normally dissipated by the latter is used to evaporate water. The device maintains the efficiency of a commercial solar cell, while at the same time providing clean water at a higher production rate than most existing devices.
The integration of both functions in a single device improves energy efficiency, and the authors suggest their device could help transform electricity power plants from water consumers to fresh water producers. They hope it will potentially contribute to wastewater reuse in regions where solar irradiation is abundant and fresh water is scarce.