The mirrors at a concentrating solar power (CSP) plant must stay clean to reflect the maximum energy to the power tower. With tens of thousands of mirrors, though, cleaning them is a formidable challenge. At Oak Ridge National Laboratory, Dominic Lee, sustainable electricity program manager, and his colleagues hope to simplify the process with a specific veneer. “It’s almost like a self-cleaning coating,” Lee explains. “This is especially important since most of the CSP plants are in arid environments with lots of dust.”

At the Ivanpah Solar Electric Generating System Facility in the Mojave Desert, an anti-soiling coating (right) causes water to bead up much more than it does on the mirror without a coating (left), and this technology can automatically clean the mirrors. Image courtesy of Bart Smith of Oak Ridge National Laboratory.

Lee and his team developed a super-hydrophobic coating. A drop of water that hits it dances around collecting dust particles – like on a scorching skillet – and then rolls off. What’s more, says Lee, “it doesn’t leave any residue.”

The coating must also be very thin to admit as much sunlight as possible. That thin layer, though, must bond tightly to the mirror so it stays in place for years. “From modeling and chemistry,” Lee explains, “we developed a polymer coating with nanoparticles suspended in it.” Through chemically created cleaning, this coating helps a CSP plant get as much energy as possible to the power tower.