New smart windows are powered by rain and wind

Science : Smart glass changes from transparent to translucent in order to block certain wavelengths of light and reduce the amount of heat passing through. Although such glass could have many uses, powering it has been difficult and expensive because of the need for external energy sources, such as power outlets, batteries, or solar panels. Now researchers have developed a self-powered system made up of two layers of nanogenerators. One layer, which is coated with nanoscopic pyramids made from a negatively charged silicone material, harvests static electricity from raindrops. The drops collect a positive charge as they fall through the air and then transfer that charge to the glass as they strike it. The other layer, which is composed of a series of tiny springs placed between two thin sheets of plastic, harvests electricity from the wind as it strikes the window and compresses the springs. The glass is not yet ready for commercialization, however, because the researchers want to boost its energy efficiency and find a way to store the energy it creates.