A group of Chinese scientists are proposing to scavenge the large amounts of wasted wind energy in cities. According to a white paper in the online edition of ACS Nano, the authors introduce a hybridized nanogenerator that consists of a solar cell and a triboelectric nanogenerator (TENG), which can be used to individually or simultaneously scavenge solar and wind energies.
The team's device structure incorporates a vibration film at the middle of the TENG that includes a Kapton film with two copper (Cu) electrodes on both sides, where the FEP (fluorinated ethylene propylene) film as the triboelectric layer was affixed on the copper electrode. Another two copper electrodes were fixed on the top and bottom of the acrylic substrate, respectively, resulting in an air gap has been created between the two copper electrodes, NanoWerk reported.
The TENG's dimensions are tiny: The thickness of both the Kapton film and FEP film is about 25 µm, and the thickness of the copper electrode is about 200 nm. The air gaps between the vibration film and the copper electrode on the acrylic substrate are 2 mm, so that the height of air intake is about 4 mm.
While the hybrid solar cell / TENG device could ideally be installed on rooftops, individual TENG arrays could be used anywhere to capture air movement, for instance, at air conditioner units' outlets.
In their experiments, the team used a homemade Li-ion battery with a TiO2 nanotube array as the electrode material to store energy generated by the hybridized nanogenerator.
"Our research holds great promise for practical applications to maximize solar and wind energies scavenging from the environments in the city areas for realizing some self-powered functions – such as sensors – in a 'smart city' environment," concludes Yang in the paper. "The next stages in our investigations will focus on the following two aspects: the first one is to improve the stability of the hybridized device output; the other one is design a new management circuit for TENG to obtain a higher current signals and voltage about 5V."
(a) Photograph of conventional wind turbine generator. (b) Photograph of the integrated solar cell units on the roof of a city building (c) Schematic diagram of the integrated hybridized nanogenerators on the roof of a house model. (d) Schematic diagram of the fabricated hybridized nanogenerator. (e) Photograph of the fabricated hybridized nanogenerator. Read more: A nanotechnology approach to scavenging wind and solar energy in cities