New solar system turns seawater into drinkable water without harmful waste

According to the United Nations, 2.2 billion people still lack access to safe drinking water. Many regions around the world rely on seawater desalination plants, but traditional methods such as reverse osmosis and thermal distillation are extremely expensive and energy-intensive. They also require chemical treatment and generate huge amounts of concentrated brine waste. When this salty liquid is released back into the sea, it poses a serious threat to marine ecosystems due to increased salinity and oxygen depletion.

A team of researchers from the University of Rochester, led by Chunlei Guo, professor of optics and physics, has developed a completely new approach. Their system is solar-powered, requires no chemical pretreatment, and does not create any liquid brine at all. The technology is based on specially adapted solar panels made of black metal that are treated with femtosecond lasers. This microstructure allows the surface to absorb almost all sunlight and at the same time “attract” water. The lasers on the panel create an active area that pulls a thin layer of seawater across the surface. When sunlight heats the metal, the water evaporates and liquefies into clean drinking water, while dissolved salts and minerals automatically move away to passive areas of the panel, preventing the system from clogging.

The key breakthrough is that real seawater, in addition to sodium chloride, contains magnesium and calcium, which, when evaporated, form a hard, dense crust. This process is similar to the build-up of scale in a water heater. To prevent this, the scientists designed microscopic grooves in the metal and exploited a well-known physical phenomenon called the coffee stain effect. When a drop of coffee dries, it leaves a dark ring of concentrated particles at the edges. The system uses the same principle to move salt to the edges. The technology has been successfully tested with water from the Pacific, Atlantic and Indian Oceans, with the surface cleaning itself completely.

Instead of environmentally hazardous waste liquids, this process removes almost all salts in solid form. These residues can be processed into table salt or extracted into valuable raw materials such as lithium, which is essential for making batteries for electric vehicles. Although the system currently exists only in prototype form, the researchers believe it can be successfully scaled up for industrial use.