Electricity Generating Tires: Good Concept or Just Crazy?
Mark Atwater posted on March 11, 2015 |
A look at the challenges where the rubber meets the road.

Goodyear unveiled a concept tire which can generate electricity during road normal use at the 2015 Geneva Auto Show. When I first saw this concept (here) I immediately thought, “That’s awesome.” Then I thought, “That’s impossible.”  Then I took a deep breath, overcame my mood swings and thought, “That’s going to take some really clever engineering.”

The Goodyear BH-03 tire is aimed at generating electricity to recharge batteries in hybrid or plug-in vehicles. The goal is to extend the current range and efficiency limits by having a constant source of energy. I think it’s a great idea and the direction the technology needs to progress, but it’s easier said than done.

The tire is presented as using a combination of piezoelectric and thermoelectric energy generation while doing its normal job of conveying a vehicle from Point A to Point B. These two methods are in direct conflict with current tire design, and that’s why I see it as a great challenge in engineering but also as a great opportunity to make some radical improvements.

The trouble with piezoelectric materials is that they rely on stress - and the associated strain - to create electricity. There are a variety of natural and engineered piezoelectric materials, but none are both efficient and soft. This is a problem because one of the main benefits of the pneumatic tire is that it reduces stress which is transmitted as vibration and results in an overall rocky ride. The brittle nature of most piezoelectric materials also eliminates their application in direct road contact, so they would be further shielded by the rubber of the tire. The piezoelectric material would have to be exceptionally efficient, very soft and/or attached to a wagon wheel to get significant power out.

Thermoelectric materials rely on a temperature gradient, not just temperature to create power. Most state-of-the-art thermoelectrics are based on semiconductors as both p-type and n-type materials are needed to create a current. Thermoelectrics also have an optimum temperature for power generation. Bismuth and antimony tellurides hit peak efficiency in a reasonable temperature range, but some of the more efficient TEs peak at a few hundred degrees Celsius, much higher than rubber would perform at during normal use (Wait! Does this give me a good reason to do burn outs?).

They also suggest the tire could absorb heat from sunlight to create power even while parked. Why wouldn’t we paint the whole car with this? Black worked well for Batman. Again, the temperature gradient is also necessary, and the tire is claimed to absorb heat like crazy, not dissipate it (which would likely have to occur inside the tire and necessitate a pressure regulation scheme). They do mention cooling holes in the tire, but it is not evident this would be sufficient. Current tires are designed to dissipate heat to reduce wear, so this would be a major shift in thinking and technology.

Another drawback is price. I scoff at the price for cheap, run-of-the-mill tires; I cannot begin to imagine the cost associated with all that technology nor begin to afford a blowout (stupid potholes!).

So even after regulating my mood, I’ve returned to the thought, “That’s awesome.” Tires are already very complex in structure. Generating electricity from them is insanely complex. That’s why we need it. If the engineers working on the technology can overcome the obstacles, that means a lot of cool advancements in sustainable energy generation. If we don’t think big, we don’t get far. I wish them success.

The video below shows more about the technology.

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