Scientists claim to draw electricity from water droplets

Vibration from water droplets hitting piezoelectric material can generate electricity

Published: Tuesday 11 February 2020

Technology today is expanding rapidly, as is its hunger for power. From smartphones to space runs, we need electricity to power them all.

Experts across the globe have been trying to generate electricity in new ways. We are now generating electricity from unconventional sources like waste.

There have been efforts to generate electricity from rain even. Vibration from water droplets hitting piezoelectric material can generate electricity.

Piezoelectric materials are materials that produce an electric current when they are placed under stress. Crystals such as quartz are the perfect examples of piezoelectric materials.

With the help of these materials, the kinetic energy of raindrops can be converted into electrical energy. But previous models could not retain the energy produced. Their energy conversion efficiency was low.

A research team led by scientists from the City University of Hong Kong has recently developed a droplet-based electricity generator (DEG). It features a field-effect transistor (FET)-like structure that allows for high energy-conversion efficiency and instantaneous power density increased by thousands of times compared to its counterparts.

The findings of their study were published in Nature magazine. The scientist used PTFE (Polytetrafluoroethylene) as a coating for the electrodes in the FET. PTFE is an electret material with a quasi-permanent electric charge. They are very similar to capacitors.

PTFE materials can store electrical energy in an electric field. The FET consists of an aluminium and an indium tin oxide electrodes with a PTFE coating.

So whenever a raindrop hits the electrodes, PTFE allows electrodes in a closed-loop to generate uninterrupted power. This system can handle extreme rainfall, the charge will keep on increasing till a saturation point.

A drop of 100 microlitres (one-millionth of a litre) of water released from a height of 15 centimetre can generate a voltage of over 140 volts. That is enough to light up 100 small light-emitting diodes briefly, according to the study.

DEGs can be used wherever the liquid is in contact with something solid — from rooftops to umbrellas, the researchers said.

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