An international team of scientists from the United States, Canada, Egypt and Ireland has developed a snow-based triboelectric nanogenerator (TENG) that creates electricity from falling snow. The snow-TENG, described in the journal Nano Energy, can produce a power density of 0.2 mW/m2, and open circuit voltage up to 8 V. The device also works as a self-powered sensor to monitor snowfall rate, accumulation depth, wind direction, and speed in snowy/icy environments.
Snow-TENG: (a) harnessing and sensing biomechanical movements by attaching a snow-TENG to different locations of the human body; (b) measurement of the electrical output from a snow-TENG device that uses a snowfall mode when attached on the (i) shoulder, (ii) wrist, and (iii) knee; (c-i) a photograph of the snow-TENG device assembled and attached to the bottom of a snow boot as a self-powered biomechanical sensor; (c-ii) electrical outputs from the snow-TENG as the wearer performs different movements — running, jumping, walking, and marching. Image credit: Ahmed et al, doi: 10.1016/j.nanoen.2019.03.032.
The snow-TENG is small, thin and flexible like a sheet of plastic, and generates charge through static electricity.
“Static electricity occurs from the interaction of one material that captures electrons and another that gives up electrons. You separate the charges and create electricity out of essentially nothing,” said senior author Professor Richard Kaner, from the University of California, Los Angeles, and Tanta University, Egypt.
Snow is positively charged and gives up electrons. Silicone — a synthetic rubber-like material that is composed of silicon atoms and oxygen atoms, combined with carbon, hydrogen and other elements — is negatively charged. When falling snow contacts the surface of silicone, that produces a charge that the device captures, creating electricity.
“Snow is already charged, so we thought, why not bring another material with the opposite charge and extract the charge to create electricity?” said co-author Dr. Maher El-Kady, a researcher at the University of California, Los Angeles.
“While snow likes to give up electrons, the performance of the device depends on the efficiency of the other material at extracting these electrons. After testing a large number of materials including aluminum foils and Teflon, we found that silicone produces more charge than any other material.”
“About 30% of the Earth’s surface is covered by snow each winter, during which time solar panels often fail to operate,” he said.
“The accumulation of snow reduces the amount of sunlight that reaches the solar array, limiting the panels’ power output and rendering them less effective.”
“The new device could be integrated into solar panels to provide a continuous power supply when it snows.”
The snow-TENG can be used for monitoring winter sports, such as skiing, to more precisely assess and improve an athlete’s performance when running, walking or jumping. It also has the potential for identifying the main movement patterns used in cross-country skiing, which cannot be detected with a smart watch.
The device could usher in a new generation of self-powered wearable devices for tracking athletes and their performances. It can also send signals, indicating whether a person is moving. It can tell when a person is walking, running, jumping or marching.
The researchers used 3D printing to design the device, which has a layer of silicone and an electrode to capture the charge.
“We believe the device could be produced at low cost given the ease of fabrication and the availability of silicone,” Professor Kaner said.
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Abdelsalam Ahmed et al. 2019. All printable snow-based triboelectric nanogenerator. Nano Energy 60: 17-25; doi: 10.1016/j.nanoen.2019.03.032
