AsianScientist (Sep. 25, 2014) – A team of researchers has found a way to harvest wind energy by using the interaction between a rigid plate and the fluttering of a flag woven from conducting material, a phenomenon known as flutter-driven triboelectrification. The results, published in Nature Communication, show excellent performance and can potentially be used to charge portable devices or even larger capacitors.
Renewable energy sources such as solar and wind power are increasingly popular, but often run into efficiency and capacity issues, forcing researchers to devise novel methods of harnessing the vast amounts of sustainable power from these sources.
Now Professor Kim Ho-Young from Seoul National University and his team have managed to study the behavior of fluttering flags and the dynamics of the movement, using them to generate enough electricity to charge up capacitors of different sizes by varying the distance between the flag and the plate, the length of the flag, and the air velocity. They managed to find conditions suitable for producing an electric signal which can be differentiated by a pushing or sliding mode triboelectric generator.
The underlying mechanism relies on the contact-propagation-separation of the flag induced by the flutter. Interestingly, the researchers showed that the distance between the flag and the plate had a negligible effect on the stability of the flag. Instead, the onset velocity for flutter depends mostly on the bending stiffness, incoming air velocity and length of the flag. They also noted that once fluttering had occurred, it would continue even if the air velocity were to drop far below the critical value, implying that intermittent winds would be less of a problem under this system.
Further experiments analyzed the effectiveness of the system in an open environment; firstly attached to a weathercock and secondly mounted to the roof of a car moving at 70 km/h. Under the first arrangement, the system was able to rotate to face an arbitrary wind direction, naturally orientating with the wind. In the second, the system was found to be not only securely mounted, but, like the first, showed suitable charging times for attached capacitors.
The implementation of this work not only holds great implications for the energy production industry and the search for renewable, sustainable energy sources, but also for developing countries or villages that face a constant shortage of power.
The article can be found at: Bae et al. (2014) Flutter-driven Triboelectrification for Harvesting Wind Energy.
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Copyright: Asian Scientist Magazine; Photo: Nick Johnson/Flickr/CC.
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