Scientists have created flags that can generate electrical energy using wind and solar power. These flags were developed using flexible piezoelectric strips and flexible photovoltaic cells.
Piezoelectric strips allow the flags to generate power through movement, while the photovoltaics harness electric power by using solar cells.
The study, conducted by researchers at The University of Manchester, is the most advanced of its kind to date and the first to simultaneously harvest wind and solar energies using inverted flags.
The newly developed energy harvesting flags are capable of powering remote sensors and small-scale portable electronics which can be used for environmental sensing such as to monitor pollution, sound levels and heat.
The goal of the study was to create inexpensive and sustainable energy harvesting solutions that can be deployed and left to generate energy with little or no need for maintenance. The strategy is known as “deploy-and-forget” and is a model that smart cities may adopt in the near future while using remote sensors.
“Under the action of the wind, the flags we built bend from side to side in a repetitive fashion, also known as Limit-Cycle Oscillations. This makes them perfectly suited for uniform power generation from the deformation of piezoelectric materials. Simultaneously, the solar panels bring a double benefit: they act as a destabilizing mass which triggers the onset of flapping motions at lower wind speeds, and of course are able to generate electricity from the ambient light,” said Jorge Silva-Leon, from Manchester’s School of Mechanical, Aerospace & Civil Engineering and lead author of the study.
Wind and solar energies tend to possess intermittencies that compensate each other. The sun does not shine during stormy conditions, whereas calm days with little wind are usually associated with sunny days. This makes wind and solar energies a perfect combination for simultaneous harvesting.
How they did it
The team used and developed unique research techniques such as fast video-imaging and object tracking with advanced data-analysis to prove their flags worked. The developed harvesters were tested in wind speeds varying from 0 m/s (calm) to about 26 m/s (storm/whole gale) and 1.8 kLux constant light exposure, simulating a wide range of environmental conditions. Under these operation conditions, total power outputs of up to 3-4 milli-Watts were generated.
“Our piezo/solar inverted flags were capable of generating sufficient power for a range of low power sensors and electronics that operate in the micro-Watt to milli-Watt power range within a number of potential practical applications in avionics, land and sea remote locations, and smart cities. We hope to develop the concept further in order to support more power-demanding applications such as an eco-energy generating charging-station for mobile devices,” said Dr. Mostafa Nabawy, co-author of the study.
