Electricity from Raindrops

While the entire world is worried about managing the battery wastes that will create a big challenge by 2050, Indian researchers have created an excellent device that will literally use water to generate electricity to support small electronic devices…

Liquid-solid Interface Triboelectric Nanogenerator

Researchers from IIT Delhi have designed and fabricated a device that can generate electricity from water drops, raindrops, water streams, and even from ocean waves using ‘Triboelectric Effect’ and ‘Electrostatic Induction’. The device is called ‘Liquid-solid Interface Triboelectric Nanogenerator’. The generated electricity can be stored in batteries for further use.

The device has a very simple structure consisting of specially designed nanocomposite polymers and contact electrodes and can generate a few Milliwatt (mW) power, which is sufficient to power small electronic devices like watches, digital thermometers, radio frequency transmitters, healthcare sensors, pedometers. When compared to conventional methods, such as the use of the piezoelectric effect, the present device can generate significantly more electricity.

Construction of the device

The researchers have successfully incorporated nanostructures into a polymer matrix, which has enhanced the film’s surface roughness, polarizability, and hydrophobicity, among other characteristics, as a result. Due to the enhancement in the above property, the flexible film is used to fabricate the device where raindrops have just to slide down and can generate electricity. The artificially created rough surface allows to generate more charge and superhydrophobic properties of the solid surface help to roll the water drop without getting stick to the surface.

The IIT Delhi research team also explored the underlying mechanism of the electricity generated when the water drop comes in contact with the solid surface and it is shown that saline water drops generate more electricity.

Background of the development

Prof. Neeraj Khare from the Department of Physics and his group at the Nanoscale Research Facility (NRF), IIT Delhi, have been working on harvesting electrical energy from  to-be-wasted mechanical vibrations using the triboelectric effect. The group has filed an Indian patent on the various aspects of the use of ferroelectric polymer for harvesting mechanical energy including the present device.

Commenting on the high-potential development, Prof. Khare said, “Triboelectric effect is a known phenomenon for a long time, and in this effect, charges are generated when two surfaces are in friction. The best example we see are sparkling lights when we move the blankets/jackets. It is only lately that it has been extensively investigated as a practical alternative for energy harvesting.”

Supporting organisations

The Ministry of Electronics and Information Technology (MeitY) and the Department of Science and Technology (DST), Government of India, have supported the research work under NNetRA project.

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