Hydropower, but different: generating energy from rain

Global warming is an increasing threat, which necessitates using renewable energy sources. Hydropower from flowing water can provide us with mechanical energy, which can then be converted into electrical energy. Researches from the UTwente and South China Normal University have now designed an electrical generator that generates energy from falling raindrops.
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In short

  • Transitioning to a sustainable energy source is important to combat climate change
  • Generating sustainable energy from hydropower, from drops falling from the sky. This study, by researchers from the UTwente and South China Normal University, is ground-breaking.
  • The force of a raindrop redistributes the oppositely charged particles on the capacitor and thus generates electrical energy.
Efficient

It is not the first time that energy has been produced from raindrops. However, now it is possible to do this more efficiently. This new electrical generator works like a permanently charged capacitor, also known as an electret. The researchers injected charges into an insulating layer of this capacitor. They used a new technique with an electrical field to adjust the contact surface of droplets. The force of a raindrop redistributes the oppositely charged particles on the capacitor and thus generates electrical energy.

Increase in energy

The number of injected charges determines the amount of power generated in the capacitor. The researchers were able to increase the number of injected charges by using high-strength composite material. The smart design of the electrodes allowed the redistribution of the charge in the generator to take place most efficiently. The researchers managed to convert 11.8% of the mechanical energy of a falling droplet into electrical energy. It is a significant improvement in efficiency compared to similar devices. They also showed that the efficiency of the process does not decrease after 100 days. This means that the device can be used for a long time after only 15 minutes of charging.

Applications

The researchers’ approach is not limited to harvesting energy from droplets. Niels Mendel, one of the researchers, says: “Our method could also be used in other applications in which mechanical energy is converted in electrical energy. For example, from waves or for sensors, or in portable devices.” Further development could lead to an increase in efficiency by optimising the generator, which would allow even more energy to be obtained from rain.

Date: 21 July 2020
Source of tekst: Universiteit Twente

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