From energy-generating nightclubs to a T-shirt that charges your phone, there are many intriguing concepts for harnessing everyday movement, and even sound, to generate electricity. Until now, most of those concepts have used piezoelectric technology, meaning that as mechanical stress is placed on certain materials, they generate a small electronic charge. The key word here, however, is small. While piezoelectric generation may have potential for small-scale charging of gadgets and other low-energy devices, it holds little potential for larger scale deployment
EarthTechling reports, however, on research lead by Zhong Lin Wang, a professor of materials science and engineering at the Georgia Institute of Technology, into "tribo-electric" energy generation. Deriving from the Greek for "rub," tribo-electric generation works based on the friction created when two materials rub together. (The electric shock you get when you pick your kid up off a slide in the playground is an example of tribo-electric power.)
According to Wang, tribo-electric technology may eventually provide the means to generate much larger amounts of electricity from a broader range of sources including waves, walking, urban traffic and even, potentially, rainfall. Wang's team has developed a prototype generator which, they say, solves many of the challenges of turning random, sometimes unpredictable movement into usable power. Here's how Earthtechling describes the set up:
Their prototype comprises a disc about 10 centimetres (four inches) across, designed to show the potential from a small, portable generator moved by ambient energy. Inside are two circular sheets of material, one an electron "donor" and the other an electron "receiver," brought together through rotary movement. If the sheets are separated, one then holds an electrical charge isolated by the gap between them.
Sandwiched between the two discs is a third disc with electrodes, which bridges the gap and helps a small current to flow. At a top speed of 3,000 revolutions per minute, the device generated 1.5 watts. This gave it an energy efficiency of 24 percent, three times greater than piezoelectric, the previously best source of mechanical electricity harvesting -- and as efficient as magnetic-induction turbines.
In the video below, Wang explains the evolution of their prototype, and even suggests that it could be commercialized and brought to scale within five years to begin supplying significant amounts of energy from sources that have previously been left untapped.
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