Scientists in Indiana have created a paint so incredibly white that it could theoretically help save the planet. The Purdue University researchers say the ultra-white paint reflects more than 98% of the sunlight that hits it, compared to between 80% and 90% for standard white paints. The paint reflects both light and heat and the researchers say using it on rooftops could reduce the need for air conditioning and prevent urban "heat islands," the Washington Post reports. Lead researcher Xiulin Ruan, a professor of mechanical engineering, shared some math: If you applied the paint to a roof measuring about 1,000 square feet, "we estimate you could get a cooling power of 10 kilowatts," he says. "That's more powerful than the central air conditioners used by most houses."
In a press release, the researchers say they considered around 100 materials for the paint before settling on barium sulfate, which is used in photo paper and cosmetics. They used different-sized particles of the compound to achieve maximum reflectance. Ruan says a "very rough calculation" suggests that as a last resort, the paint could be used to lower global temperatures. "We estimate we would only need to paint 1% of the Earth's surface with this paint—perhaps an area where no people live that is covered in rocks—and that could help fight the climate change trend," Ruan says, per the BBC. He says the paint costs about as much to produce as ordinary paints and it should reach consumers within the next two years. Ruan says he has spoken to a museum that wants to display the ultra-white paint next to a "super black" paint developed by nanotech researchers that absorbs almost all light. (Read more discoveries stories.)