Piezoelectrics: Cool, useful, but NOT an energy solution.

Piezoelectrics are an increasingly popular “green energy” topic.  Piezoelectrics are materials that generate a small voltage whenever they are mechanically deformed.  Recently innovative solutions that use Piezoelectrics to harness energy have been tested on everything from roads to subway foot traffic.  Innowattech is one company that has embedded their technology in roadways to harness energy from cars.

But there is a problem with how we are discussing this technology.  Like anything that obeys the laws of physics, Piezoelectrics only generate energy at the expense of the system – it isn’t free energy.  There are actually  lot of great uses for Piezoelectrics out there, but we won’t discover them if we keep talking about Piezoelectrics as a “free energy” solution.  If we look at this technology in terms of generating electricity, it is a failure.  Piezoelectrics on roads take energy at the expense of the cars’ fuel efficiency, and Piezoelectrics under subway floors will make you tired walking through the subway just like walking on the beach.

But in reality this technology is not about energy generation – it is about infrastructure.  Like a battery, the technology doesn’t create energy but makes it efficient to transport energy.  So it could be a great technology in roads if it saves us infrastructure costs like installing electric cables for lighting.  It could also be used to light the road only when cars drive over them – here it is used as an information technology and does save a lot of electricity by cutting out waste in our system.

Another way the technology could actually generate “free electricity” is if we used it to replace friction in our engineered  systems that is used to slow something down.  There are lots of ways to do this including regenerative motors (like in the prius), flywheels, or recapturing the heat created by friction.

So, instead of building Piezoelectrics into subway floors, we could put them into turnstiles replacing the built in friction resistance (this is being done, but I don’t think the energy produced is significant enough to be more than a “green gesture”).   We could put them in the road only on the downhill lanes where cars are breaking.  I hear you thinking, “So this IS an energy solution after all!”  Well it can be, but the smart way to think about it is that it could be a tool to SAVE energy that our systems are already wasting.

Even so, the energy that Piezoelectrics produce is tiny compared to the amount we consume every day and should only be thought of as a local power supply for low power devices.  My point is,  don’t be greenwashed into thinking this is some magic paint you can spread on every surface to power your life.  Don’t be fooled by the argument “The cars will never notice the difference – the pedestrians won’t even feel it.”  You can’t cook peter to eat paul.  Unless you’re these guys and peter is innotech.