Water is everywhere; safe drinking water is not. So Jia Zhu has created a thin metal sheet capable of floating on the surface of a body of water, absorbing lots of sunlight and using the energy to generate steam that condenses into clean water.  “It only needs two things. The first is water—no matter what kind of water  you have—and the second is the sun,” says Zhu.

The device could be used to desalinate seawater or treat polluted water: after the water is turned into steam, what’s left are salts or solidified contaminants that can be easily collected.

He also envisions other ways to put the ingenious apparatus to use. “The steam doesn’t have to be condensed,” he says, suggesting that it could be used to produce power.

—Yiting Sun