When exposed to winds with a velocity as low as 2m/s, the device can produce a voltage of 3V and generate electricity power of up to 290μW, which can power a commercial sensor that can then send acquired data to a mobile phone or a computer.
The light and durable device wind harvester also diverts any electricity that is not in use to a battery, where it can be stored to power devices in the absence of wind.
The scientists said their invention has the potential to replace batteries in powering LED lights and structural health monitoring sensors.
Measuring 15cm by 20cm, the NTU team said the device can easily be mounted on the sides of buildings and would be ideal for urban environments such as Singaporean suburbs where average wind speeds are less than 2.5m/s, outside of thunderstorms.
The team’s findings have been published in Mechanical Systems and Signal Processing.
In their paper the team said the wind harvester utilises the so-called galloping effect coupled with triboelectric-based energy conversion to convert flow-induced structural vibration into electricity.
The team added that the wind harvester comprises a host cantilever beam, a stopper, and a middle plate with one rotation degree of freedom. The triboelectric layers and electrodes are placed in between the surface of the stopper and middle plate. A bluff body is fixed at the free end of the host beam to induce galloping vibration, which drives the middle plate to contact with the stopper periodically, which generates electricity due to the triboelectric-based conversion mechanism.
In a statement, project lead Professor Yang Yaowen, a structural engineer from NTU’s School of Civil and Environmental Engineering (CEE), said: “As a renewable and clean energy source, wind power generation has attracted extensive research attention.
“Our research aims to tackle the lack of a small-scale energy harvester for more targeted functions, such as to power smaller sensors and electronic devices.”
Prof Yang continued: “The device we developed also serves as a potential alternative to smaller lithium-ion batteries, as our wind harvester is self-sufficient and would only require occasional maintenance, and does not use heavy metals, which if not disposed of properly, could cause environmental problems.”
In laboratory tests, the wind harvester powered 40 LEDs consistently at a wind speed of 4m/s. It could also trigger a sensor device, and power it sufficiently to send the room temperature information to a mobile phone wirelessly.
The NTU team will be conducting further research to further improve the energy storage functions of their device, as well as experiment with different materials to improve its power output. The research team is also in the process of filing for a patent on the device, which has received interest from industry.