Weather could power the next generation of smart windows. Researchers have created glass that tints by harvesting energy from wind and precipitation. The approach offers an alternative to other smart windows powered by batteries, solar panels, and even standard power outlets.

The new glass uses nanosized generators powered by triboelectrics—the static electricity produced by friction when two materials touch. When activated, the generators, which rest in two layers atop a single pane of glass, create an electric current that tints the clear window a dark shade of blue.

The outermost layer of generators harvests static energy from rain. When a raindrop falls from a cloud, the contact between the water and the air creates a positive charge within the droplet. When the droplet strikes the glass, which is coated with nanoscopic pyramids made from a negatively charged silicone material called polydimethylsiloxane, it creates an electric current.

The second layer of nanogenerators lies just beneath the first and harvests energy from the wind. This layer consists of two sheets of charged, see-through plastic that are separated by nanoscopic spring coils. As wind pushes against the window, the springs compress and create an electric current as the charged plates of plastic approach each other.

In experiments, the glass produced up to 130 milliwatts per square meter, enough to power a pacemaker or a smart phone while it’s asleep, This output might suit many applications, such as being a power source for home or office electronics.