University of Wisconsin-Madison engineers and a collaborator from China have developed a nanogenerator that harvests energy from a car tire’s rolling friction. Xudong Wang, the Harvey D. Spangler fellow and an associate professor of materials science and engineering at UW-Madison, and his PhD student Yanchao Mao have been working on this device for about a year.

Nanogenerators Mounted to Toy Car Tires.  Click image for the largest view. More info in the study paper and abstract.  Image Credit: University of Wisconsin-Madison.

Nanogenerators Mounted to Toy Car Tires. Click image for the largest view. More info in the study paper and abstract. Image Credit: University of Wisconsin-Madison.

Its an innovative method of reusing energy. The nanogenerator ultimately could provide automobile manufacturers a new way to squeeze greater efficiency out of their vehicles. Wang said the nanogenerator provides an excellent way to take advantage of energy that is usually lost due to friction.

The researcher team reported their development in a paper published in the journal Nano Energy.

The nanogenerator relies on an electrode integrated into a segment of the tire. When this part of the tire surface comes into contact with the ground, the friction between those two surfaces ultimately produces an electrical charge – a type of contact electrification known as the triboelectric effect.

During initial trials, Wang and his colleagues used a toy car with LED lights to demonstrate the concept. They attached an electrode to the wheels of the car, and as it rolled across the ground, the LED lights flashed on and off. The movement of electrons caused by friction was able to generate enough energy to power the lights, supporting the idea that energy lost to friction can actually be collected and reused.

Wang explained, “The friction between the tire and the ground consumes about 10 percent of a vehicle’s fuel. That energy is wasted. So if we can convert that energy, it could give us very good improvement in fuel efficiency.”

The nanogenerator uses the triboelectric effect to harness energy from the changing electric potential between the pavement and a vehicle’s wheels. The triboelectric effect is the electric charge that results from the contact or rubbing together of two dissimilar objects.

During initial trials, Wang and his colleagues used a toy car with LED lights to demonstrate the concept. They attached an electrode to the wheels of the car, and as it rolled across the ground, the LED lights flashed on and off. The movement of electrons caused by friction was able to generate enough energy to power the lights, supporting the idea that energy lost to friction can actually be collected and reused.

“Regardless of the energy being wasted, we can reclaim it, and this makes things more efficient,” Wang said. “I think that’s the most exciting part of this, and is something I’m always looking for: how to save the energy from consumption.”

The researchers also determined that the amount of energy harnessed is directly related to the weight of a car, as well as its speed. Therefore the amount of energy saved can vary depending on the vehicle. But Wang estimates about a 10 percent increase in the average vehicle’s gas mileage given 50 percent friction energy conversion efficiency.

“There’s big potential with this type of energy,” Wang said. “I think the impact could be huge.”

Huge indeed. A few moments thought on all the friction in the developed world is quite an exercise. But lets hope that the team realizes that as much as the energy recapture and reuse has a powerful appeal, the technological application has to be simple and cheap for mass utilization.


Comments

1 Comment so far

  1. zvibenyosef on June 30, 2015 3:28 PM

    The question is, are they collecting energy which would otherwise be wasted, or merely slowing the vehicle down even more than it would normally by friction alone. A better alternative I have seen is a shock absorber which converts produces energy from uneven roads.

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