Using solar energy and nanoparticles to make saltwater drinkable, researchers from Yale and Rice University have developed a system that could potentially be used off-grid in remote areas or in domestic settings.
The system, known as nanophotonics-enabled solar membrane distillation (NESMD), incorporates a porous membrane with carbon black nanoparticles. The nanoparticles use sunlight energy to heat water on one side of the membrane, which filters out salt and other non-volatile contaminants while allowing water vapor to pass through it.
The technology comes from the Center for Nanotechnology-Enabled Water Treatment (NEWT), a multi-institutional engineering research center. Based at Rice, it includes Yale and several other partners from industry, government, and other universities. Funded with an $18.5 million grant from the National Science Foundation (NSF), NEWT was founded in 2015 to provide clean water to millions of people and make U.S. energy production more sustainable and cost-effective.
In the most widely used desalination process, saline water passes through a membrane and emerges, desalinated, on the other side. Known as reverse osmosis, the process is very energy-efficient, but doesn’t work well on water with very high salinity. Another commonly used type of desalination system involves thermal processes in which water is evaporated and then condensed. It’s effective, but this method uses a lot of energy due to the amount of heat required. Thermal processes are often situated near power or chemical plants that provide steam as the heat source.