New nanogenerators collect friction energy from rolling tires Team of engineers from University of Wisconsin-Madison and a collaborator from China have developed a new nanogenerator that is able to generate power from friction created by rolling tires of the car. As with a big part of today�s automotive technological innovations, it is aimed at efficiency. In the future such technology could help harvest otherwise wasted energy to squeeze just that extra bit of efficiency out of cars and other vehicles.

It is said that this technology is the first of its kind and it took about a year for the scientists to reach this stage in the development of the project. The nanogenerator harvests the wasted tire friction energy by relying on the triboelectric effect. It is the electric charge that results from the contact or rubbing together of two dissimilar objects. The generator harnesses energy from the changing electric potential between the pavement and a vehicle wheels.

Scientists said that it could become a very useful way to use the energy that is usually wasted due to friction � taking advantage of this lost energy would improve efficiency, which is a major goal in today automotive industry. Professor Xudong Wang, one of the authors of the study, noted that �the friction between the tire and the ground consumes about 10 % of a vehicle fuel� and, since that energy is simply wasted, �if we can convert that energy, it could give us very good improvement in fuel efficiency�.

Improving fuel efficiency would benefit everyone � it would help automotive industry meet new strict regulations for emissions, make traveling just that little bit cheaper and would improve energy efficiency which would benefit environmental causes as well.

The technology is depending on an electrode integrated into a segment of the tire. When it 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. The segment should not cause any disadvantages to the handling and performance of the car.

To test the technology, team used a toy car with LED lights. Engineers attached an electrode to the tires of the toy car and watched the LED lights as the car was rolling forward and they flashed on and off as electrodes came with contact with the surface. The friction was strong enough for the electrodes to harvest enough energy to power the lights, which means that scientists confirmed the idea that wasted friction energy can be collected and reused.

Engineers also determined that the amount of energy harnessed is directly related to the weight of a car and the speed it is going at. It means that different vehicles would waste different amounts of energy and different percentage of it could be saved using this method. However, scientists estimated that fuel efficiency could be improved by as much as 10%, given 50% friction energy conversion efficiency. This is a very significant improvement.

As cars are supposed to be greener and greener, everyone involved will have to look for new innovative ways to improve efficiency. This is always largely about collecting wasted energy. That is why this technology has a huge potential and 10% savings in terms of fuel consumption are pretty big leap forward. But, as usual, we will have to wait and see how these nanogenerators develop and when they will be introduced for practical application.