Around the world, 2.2 billion people do not have reliable access to safe drinking water. The ocean contains plenty of it, but it is undrinkable because of the salt. Traditional desalination requires enormous amounts of energy and produces brine, a salty liquid that damages the sea when dumped back into it.
Researchers at the University of Rochester have developed a solar-powered desalination system that solves both problems. The system, led by Professor Chunlei Guo, turns seawater into fresh water while recovering nearly 100 percent of the dissolved salts as solid material instead of toxic liquid waste.
The device uses a metal panel etched with special lasers. This treatment makes the metal deeply black, so it absorbs sunlight efficiently, and creates a "superwicking" surface that pulls water across itself like a sponge. The panel is divided into two zones. In the active zone, sunlight heats and evaporates seawater, producing fresh vapor. As water disappears, salt crystals do not build up on the surface. Instead, the system continuously sweeps them into a separate passive zone where they collect as solid material.
The researchers tested the method with water from the Pacific, Atlantic, and Indian Oceans. In a second study, they adapted the same surface to extract lithium from salt, a valuable metal used in batteries for electric cars and phones.
Although the system currently exists only in the laboratory, it represents a significant advancement. A single sheet of black metal, powered by the sun alone, could produce drinking water, harvest salt, and recover battery metals from the same water.