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These tiny wearable electric generators harvest wind energy while you walk
Blowing out of the necessities of invention, a new type of wearable electric generator that produces energy via Mother Nature's wind has been discovered by researchers at the Chinese Academy of Sciences. Rather than acting as a tiny turbine to create low cost power, these small devices operate on the triboelectric principle by using the effect of static electricity, where materials are charged electrically when pulled off a second source material.
Although it works with wind, it’s not exactly a turbine. Instead, this generator collects energy through a mechanism similar to what produces static electricity called the triboelectric effect. This phenomenon occurs when a material becomes electrically charged after it’s separated from another material.
Attached to a person's arm as they walk, jog, or cycle, these triboelectric nanogenerators employ a pair of strips inserted into a tube, which tremble and rub together when air is forced into the cylinder, allowing the device to snare and store energy.
In a new study published in the online journal Cell Reports Physical Science, the team reports success with breezes as slight as 3.6 miles per hour, but is most efficient when winds are stronger in the range of 8.9 to 17.9 miles per hour. Wind-to-energy conversion efficiency stands at 3.23 percent, an improvement on other similar wind-harnessing inventions, but much less than specific wind energy harvesters like true wind turbines that register a conversion rate of nearly 50 percent.
Even with this limited potential, these new nanogenerators are perfect for little devices, where an optimized model can output a maximum voltage of 175 V, a current of 43 μA and a power of 2.5 mW, sufficient enough to run tiny temperature sensors or a string of 100 LEDs.
Besides having viable marketing opportunities as a wearable power unit that taps into the natural world by taming the wind, the scientists believe they can expand upon their invention to create fabrics that can harvest friction energy and metallic tabs to pull power from bending fingers. Moving forward, the Chinese Academy of Sciences crew hopes to upscale their tech to increase power output substantially but there are a number of obstacles to overcome before that stage comes to fruition.
"I'm hoping to scale up the device to produce 1,000 watts, so it's competitive with traditional wind turbines," explains Ya Yang, senior author of the study. "We can place these devices where traditional wind turbines can't reach. We can put it in the mountains or on the top of buildings for sustainable energy.”