While it’s easy to condense water from humid air, machines that harvest water from drier air require energy. Researchers have created the first water harvester that uses only ambient sunlight. The key component is an extremely porous material called a metal-organic framework that absorbs 20 percent of its weight in water from low-humidity air. Sunlight heats the MOF, releasing the water vapor, which condenses to produce liters of water per day.
