Currently, solar-powered steam generation involves vast fields of mirrors or lenses that concentrate incoming sunlight to heat large volumes of liquid to high enough temperatures to produce steam. In contrast, a new material structure, developed at MIT, generates steam when simply floated on water and placed in the sun.

The structure – a layer of graphite flakes and an underlying carbon foam – is a porous, insulating material that floats on water. When sunlight hits the structure’s surface, it creates a hotspot in the graphite. This draws water up through the material’s pores, where it evaporates as steam. The brighter the light, the more steam is generated. The material is able to convert 85% of incoming solar energy into steam.