Scientific researchers discover how to obtain electricity from raindrops

Scientific researchers discover how to obtain electricity from raindrops

Source: Economia Digital
17/12/2018

Raindrops fall at speeds between 15 and 30 km/h, depending on their size that varies between a few tenths of a millimetre and a few millimetres. Although its mass is very small, the mechanical energy that is released when a drop of rain hits a solid surface can be used to produce electricity.

Starting from that premise, a group of researchers from the Georgia Institute of Technology developed a glass surface capable of producing electricity when struck by rain, or when it deforms slightly due to air pressure. The windshields of cars are the most obvious application, although it could also serve as a coating for solar panels, which would allow electricity to be obtained from solar panels also when it rains, even at night.

The glass developed by the researchers is based on the triboelectric effect by which an electric current is produced when two materials come into contact. The glass is made up of two layers: one to capture the kinetic energy of the raindrops when they hit it – for this first layer the researchers developed “nanometric” generators that take advantage of the positive charge that raindrops obtain by rubbing with the air in its descent from the clouds and until they hit the windshield of the car. And a second layer, consisting of two sheets of plastic loaded that are kept separated from each other, to take advantage of the air resistance or capture the force of the wind. When the vehicle accelerates the air pressure it joins both layers, creating an electric current”, the researchers explain. The raindrops contain salts that are divided into positive and negative ions, so, as a result, there are separate layers of positive ions and negative that act as a capacitor to store energy.

Currently the production of any of these projects under development is limited, about 130 “milliwatts” per square meter of glass (more than what a mobile phone consumes at rest), but it is a step towards the development of effective photovoltaic panels in different meteorological conditions.

All these projects are still under development, but once the generation of energy has been proven, researchers are now looking for ways to locally store the electricity obtained in this way, for example by means of transparent supercapacitors incorporated in the glass.