Think about an average day. Here’s how mine is:
- I wake up, 30 minutes late because who actually gets up on time?
- I spend about an hour getting ready, rushing to eat breakfast and getting to the car.
- It’s a small ride to school, but it takes time because of all the traffic in the morning.
- I bore through class, waiting for lunch when I might walk to a local plaza and grab a bite, or just walk around the park. I go back to class again, waiting for school to end.
- I walk home, about 3 kilometres and the crowds of kids stomp the sidewalks I take.
- At home, I’m constantly going up and down the stairs, walking down halls, and moving around.
- Finally after I eat dinner, I sleep.
We’ll get back to this. Now, let’s talk about piezoelectricity.
PIezoelectricity is the generation of an electric charge that occurs when mechanical stress is applied to certain materials. Piezoelectric materials include Berlinite, cane sugar, quartz, Rochelle salt, topaz, tourmaline, and bone (yes, bone!). The one thing these materials have in common is the shape of their atoms.
As a simplified explanation, look at a crystal with 6 atoms — 3 positively charged and 3 negatively charged. When they are shaped like the first diagram, the overall charge of the entire crystal is neutral — the positively and negatively charged atoms cancel each other out. When mechanical energy is applied to the crystal, the arrangement of positively and negatively charged atoms shifts. This leads to one side of the crystal having a net positive charge, and the other side of it having a net negative charge; just like a battery. Attaching metal plates and wires means this difference in charge can be harnessed and used as electricity!
This is what a piezoelectric disc looks like. The “crystal” used inside is an artificial crystal called lead zirconate titanate or PZT. It uses the same concept as natural piezoelectric crystals but with a more complicated chemical formula. The material is sandwiched between two metal plates; in most cases one plate is aluminum and the other is platinum. Wires are linked to both metal plates, and that generates voltage.
This is PZT. The P is short for Pb, which is Lead. The Z is Zirconate, which is the metal Zirconium bonded to oxygen atoms, creating a negative charge. The T is Titanate which is a compound of titanium and oxygen, creating a positive charge. These ions are arranged in a Polycrystal formation. Polycrystal is a structure of crystal lattice in an asymmetrical way, meaning that it is neutral until mechanical stress is applied, which means it contains the piezoelectric effect. PZT is created when all three of these materials are broken down into powder and broken into fine particles. The solution is then treated with heat and solidified.
Let’s look back at my average day and see where piezoelectricity can be used in all of these situations. First in the morning, imagine I had an alarm clock controlled by crystals instead of batteries! Or a stove, powered by rochelle salt! Imagine roads had piezoelectric tiles in them, connected to batteries that get charged when cars ride over them. This energy could be used to power at minimum the streetlamps, if not more of the local area! This same concept of piezoelectric floors could be used in sidewalks, walkways and in homes.
If you don’t understand yet, I’m basically saying that piezoelectricity can be used everywhere.
This is such a simple, yet useful and efficient way to generate and use power and is renewable and reusable!
It does have drawbacks though. The biggest one is just the fact that piezoelectricity uses crystals. Crystals are of course a finite resource on the Earth, and we are bound to run out if we adopt this as a main source of energy. This also means that mining is used to extract crystals, which harms the environment. The way around this is to use lab made materials like PZT, and as the world advances we are finding safer, cheaper and more efficient piezoelectric materials. Most piezoelectric materials are also not the strongest — many are water soluble (such as quartz in hot temperatures), or easily broken. These are fixable problems though.
Overall, piezoelectricity is a unique, reliable, effective solution to many of our problems with renewable energy and climate change! This is the energy of the future and will light up our way to a sustainable world.