A group of engineers have developed a nanogenerator that harvests energy from a car’s rolling tire friction, which may improve the fuel efficiency or the cruising ability of electric vehicles.
An innovative method of reusing energy, the nanogenerator ultimately could provide automobile manufacturers a new way to squeeze greater efficiency out of their vehicles.
The researchers reported their development in a paper published May 6, 2015, in the journal Nano Energy. They have been working on this device for about a year.
Nanogenerator is a technology that converts mechanical/thermal energy as produced by small-scale physical change into electricity. Nanogenerator has three typical approaches: piezoelectric, triboelectric, and pyroelectric nanogenerators. Both the piezoelectric and triboelectric nanogenerators can convert the mechanical energy into electricity.
The nanogenerator which relies on 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.
“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 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, the researchers 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.
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.
