Tiny wearable wind farm harvests energy from flapping plastic strips
Researchers from the Chinese Academy of Sciences have developed a new type of wearable electric generator, which harvests energy from the wind as you walk. The team says it’s low cost and efficient enough to power small sensors and LEDs.
Although it works with wind, it’s not exactly a turbine. Instead, this generator collects energy through a similar mechanism to what produces static electricity – namely, the triboelectric effect. This phenomenon occurs when a material becomes electrically charged after it’s separated from another material.
In this case, the active component is two strips of plastic in a tube. When air flows through the tube, the strips flap about and clap together, capturing and storing energy. The team says this nanogenerator works in winds as gentle as 3.6 mph (5.8 km/h), and tests showed that it can work while attached to a person’s arm while walking. That said, it works best at wind speeds between 8.9 and 17.9 mph (14.3 and 28.8 km/h), so perhaps it would be better suited to use on a bike.
The team says that the device has a wind-to-energy conversion efficiency of 3.23 percent. That’s higher than other devices that scavenge energy from the wind, but it’s a far cry short of more dedicated wind energy harvesters. For example, although it’s not an apples-to-apples comparison, a regular old wind turbine has an efficiency of around 50 percent.
As such, the new nanogenerator would be better suited to smaller devices. The optimized version can output a voltage of 175 V, a current of 43 μA and a power of 2.5 mW, which is enough to power small temperature sensors or an array of 100 LEDs.
This new design could one day inform new types of wearable nanogenerators to power small electronic devices. Other concepts include fabrics that can harvest energy from friction and others that tap into both sunlight and movement, and metallic tabs that can harvest energy from bending fingers. Ultimately, the team plans to try to scale up the technology to produce even more power, possibly even grid-scale – although there’s still a whole lot more work to do before that stage.
"I'm hoping to scale up the device to produce 1,000 watts, so it's competitive with traditional wind turbines," says 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.”
The research was published in the journal Cell Reports Physical Science. The team demonstrates the device in the video below.