- University of Rochester scientists built laser-etched solar panels that desalinate seawater with no chemicals and no brine waste.
- The panels recover nearly all the salt as solid material.
- The system was tested successfully on water from three oceans, addressing a problem that affects 2.2 billion people.
A new kind of solar panel turns seawater into clean drinking water using only sunlight, leaving behind no toxic brine and even pulling out lithium for batteries.
The technology tackles two problems at once: the dirty waste that desalination usually produces, and a global shortage of safe water. The United Nations estimates that 2.2 billion people lack safely managed drinking water, and communities from California to the Middle East rely on desalination plants to convert ocean water to fresh.
Standard desalination comes at a cost. It is expensive, energy-hungry and dirty, spitting out brine that harms ocean life, and scale builds up inside systems and shuts them down.
The new approach, developed in the lab of optics and physics professor Chunlei Guo, sidesteps all of that. The system produces fresh water efficiently, operates without chemical pretreatment, and avoids creating brine waste. The team described the technology in the journal Light: Science & Applications, according to SciTechDaily.
At its heart is a specially engineered surface. The panels are made from black metal textured with femtosecond lasers, which gives the surface two important properties: it absorbs nearly all incoming sunlight and strongly attracts water, a characteristic known as superwicking. A thin film of seawater is drawn across the panel, and the sun does the rest.
The clever part is what happens to the salt. As the water evaporates, the laser-etched grooves carry the salts and minerals outward and away from the working surface, so they never clog the panel. Guo compares it to something most people have seen on a kitchen table.
“If you drop coffee on a surface, eventually the water evaporates and there’s a ring left at the outer edge that is the concentrated coffee particles,” he says. “We use that same principle to advance the salts to the passive region.”
That design solves a problem that has long defeated lab prototypes. Magnesium- and calcium-based compounds crystallize in hard crusts that clog panel surfaces over time, the same way mineral scale builds up inside a kettle, except seawater carries hundreds of times more dissolved salts than typical tap water.
Rather than dumping that material back into the sea, the system keeps almost all of it. The design enables nearly 100 percent salt extraction in solid form, and allows selective extraction of valuable minerals such as lithium from the residue. In companion work, the team showed the panels could be modified to pull roughly 50 percent of available lithium from Great Salt Lake water samples.
To prove it works beyond simplified lab conditions, the researchers tested real ocean water. They used samples from the Pacific, Atlantic and Indian Oceans to make sure the system could cope with varying levels of impurities.
