How to Use Your Tyres as an Energy Source

Ever been a few beers deep at the pub and started wondering: “why don’t they rig up gyms and playgrounds to generate electricity from all that movement?” Well, scientists have been onto this concept for a while and have been developing an array of technology capable of ‘soaking up’ all the errant energy we produce and lose each day.

One avenue of energy retrieval is through our tyres. Cars of the future will be equipped with equally futuristic tyres (like the Goodyear prototype above), kitted out with technology enabling them to produce energy as they consume it. An example of this technology that’s been around for years, but has flown under the radar outside of scientific circles, is a piezoelectric rig that turns your tyres into vibrational power generators.

A piezoelectric what now?

First things first, piezoelectricity refers to the generation of AC voltage by subjecting certain materials to vibration or mechanical stress. The in-tyre piezoelectric contraption relies on a commutator to extract power and direct it to the onboard electronics. For it to work, the wheels need to be able to spin freely while also maintaining continuous electrical contact with the chassis.

Here’s what the tech looks like in its current stage of development:

What you’re seeing there is a 4×40 array of flexible lead zirconate titanate (PZT) elements, bonded with a compatibly flexible adhesive to the inner surface of the tyre. Each row of 4 PZT elements is wired to be a separate generator and, as the vehicle moves, only two or three rows will be producing electricity at any give time.

The scientists responsible, Noaman Makki and Remon Pop-Iliev, say PZT bender rigs like this have been used before but only to power tyre-related devices like pressure sensors. With their arrangement, they covered as much of the tyre’s inner surface as possible to maximise the electrical output. This arrangement means there are always elements moving over the contact patch, allowing for continuous, reliable energy, so long as the vehicle is moving.

As the system is just ‘catching the energetic runoff’, so to speak, it won’t be able to generate enough electricity to power the car. We’re not yet advanced enough to be creating self-sustaining closed circuits. However, Makki and Pop-Iliev claim the piezoelectric system will generate enough electricity to power all onboard electronics. This is a big advantage for electric cars as it means your battery’s charge can be dedicated entirely to powering the engine, thus giving you a boost in mileage before you need to charge up again.

Why bother soaking up this energy?

Electric cars are still quite limited in their battery range and, while you’ll see charge stations on almost every corner in European cities, they are few and far between in Australia. Any method that can extend their range is a welcome addition. Particularly as we are struggling to get manufacturers of electric vehicles to ship their most exciting models to Australia.

We do get the hybrid vehicles, which come with an internal combustion engine to help you manage the low range of the electric system. While practical for getting you from A to B, this approach, combined with the environmental costs of building and shipping hybrid vehicles, chips away at their carbon-reducing ideals.

The scientists behind the piezoelectric developments explain:

“The need remains for a cleaner power-generation technique that allows maximum range extension with minimal environmental consequences.”Noaman Makki & Remon Pop-Iliev

Other ways to energise your tyres

Apart from building next-level spherical prototype tyres for the autonomous cars of the future, Goodyear has been busy exploring all sorts of options for reclaiming some of the energy spent by the movement of our tyres.

The company is figuring out how to construct their tyres with thermoelectric materials capable of generating energy from the heat produced by road contact. While elements like tin selenide and bismuth telluride have the capabilities they’re looking for, they need to be able to be incorporated into the tyre design without any losses in functionality and durability.

Meanwhile, Tesla has been working with regenerative braking for a good ten years now, capturing kinetic energy which would otherwise dissipate into the ether, and returning it to the battery.

And its not just tyres. Scientists and engineers are working on every element of mechanical movement, looking for places where spent energy can be recaptured. Surely it’s only a matter of time before you can pay off some of your gym membership through the energy you generate on the machines.