Behold the salt monsters. These twisted mineral crystals—formed from the buildup of slightly salty water in power plant pipes—come in many shapes and sizes. But the tiny monsters are a big problem: Each year, they cost the world’s power plants at least $100 billion because workers have to purge the pipes and scrub the crystals from filters.
Now, a solution may be at hand. Engineers can reduce the damage by coating the insides of the pipes with textured, water-repellant surfaces, a new study in Science Advances suggests. The catch: The size of the gaps in the surface matters. Surfaces textured with microscale gaps, micrometer-wide dips between tips of the surface, encourage the crystals to spread and flatten, making them tough to remove. If microscale gaps were the width of a cantaloupe, nanoscale gaps would be the width of a cherry. Surfaces textured with nanoscale gaps force the crystals to grow upward, resulting in funky shapes akin to miniature elephants and jellyfish that are much easier to remove from the pipes. In fact, these “crystal critters” stand out so much that scrubbers can easily flick them from the surfaces—or they can detach themselves from the surfaces and roll away on their own. Researchers caught their microscopic moves on camera, lending us a view of the crystals’ remarkable behaviors.