As the world’s demand for energy continues to increase, we know how important it is to develop and utilize alternative and sustainable methods of energy production. You may already be quite familiar with green energy sources or alternative energies such as hydroelectric power, wind power, biomass energy, or solar power, but did you know that there are many more opportunities for electricity generation?
In fact, something as simple as walking can generate electricity! According to the first law of thermodynamics, the Law of Conservation of Energy, energy can be neither created or destroyed; energy can only be transferred or changed from one form to another. Therefore, the mechanical energy that is produced with each of our footsteps can actually be harvested and converted to electricity! Pretty incredible right?
How is this possible?
The energy produced by our footsteps can be converted to electricity through the piezoelectric effect. The piezoelectric effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress.
When a piezoelectric material is placed under mechanical stress (in other words, physical pressure is applied), positive and negative charge centres (electrons) within the material shift and are displaced, resulting in the creation of an external electrical field. The most commonly used piezoelectric materials are ceramics such as lead zirconate titanate, barium titanate, and lead titanate.
This piezoelectric energy can then be stored for later use. This is a form of energy harvesting, the process of capturing wasted energy from naturally occurring energy sources and accumulating and storing it for future use. Isn’t it neat that such a simple everyday action such as walking provides enough pressure to generate electricity?!
Creating floor tiles out of piezoelectric materials is a great way to ensure the capture and storage of electrical energy!
Power generating floors in a Japanese train station
Piezoelectric power mats have been successfully integrated into the popular Japanese Shibuya train station in order to create self-generating energy. The mat, which is 90 square centimetres and 2.5 centimeters thick, is placed just outside the train station where millions of people pass through. In fact, it is estimated that approximately 2.4 million people pass through the Shibuya Station every day!
Each time a person who weighs approximately 135 lbs steps on the mat, 0.1 watts are generated. When you take into account the overall weight and number of people stepping on the mat in a single day, that’s enough energy to light up a holiday light display on the station’s wall, as well as an LED board that updates the total amount of electricity created in real time.
It is important that this kind of technology is utilized in highly populated locations that generate lots of pedestrian traffic, as you can imagine that a remote location such as a seldom-used footbridge in the countryside wouldn’t generate enough energy to be useful at all!
Piezoelectric tiles at NASA plaza
Visitors to NASA’s Kennedy Space Centre are greeted by a large high-tech path made up of piezoelectric tiles which not only generate electricity, but also absorb solar energy and emit Wi-Fi signals.
The 1,000 tiles are spread across 40,000 square feet, forming mosaic images of Earth, Mars, the Moon and the International Space Station. Within each of the tiles are circuit boards, solar panels, a battery, LEDs, a Bluetooth and Wi-Fi transmitter, and a piezoelectric element.
When the glass tiles are stepped on, the piezoelectric element is compressed, creating an electrical charge that lights up the LED lights within the tile and powers the Bluetooth or Wi-Fi signal which provides visitors' phones with educational and wayfinding information.
The aim of this project is to showcase “smart city” applications of the technologies used in the tile. Although the piezoelectric tiles at the NASA Kennedy Space Centre are quite flashy, this technology can also be used more practically. For example, the electricity produced by piezoelectric tiles on sidewalks or plazas can be used to power streetlights or electronic bus schedules and signs.
While I am not a fan of believing that technology alone will get us out of the climate crisis, there are some interesting solutions like piezoelectricity. In a time where it is critical to move away from fossil fuels and invest in renewable energy, we need to be creative with our green energy solutions. Piezoelectricity generation just might be a practical approach to help fuel our most populous cities.
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