New nanogenerator harvests power from rolling tires

[OKIsItJustMe]

http://news.wisc.edu/23865

[font face=Serif][font size=5]New nanogenerator harvests power from rolling tires[/font]

June 29, 2015

[font size=3]A group of University of Wisconsin-Madison engineers and a collaborator from China have developed a nanogenerator that harvests energy from a car's rolling tire friction.

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, which is the first of its kind, in a paper published May 6, 2015, in the journal Nano Energy.

...

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.

...[/font][/font]

[Sherman A1]

1. Excellent!

Thanks for posting.

[OKIsItJustMe]

2. You’re welcome.

Every little bit…

[mackdaddy]

3. Ok had to lookup what the heck a "triboelectric nanogenerator" was...

I had never heard of the "triboelectric" generators before. Basically it is a way of harvesting what we would encounter as static electricity buildup such as when scuffing your shoes across a carpet and touching a doorknob, or rubbing a balloon on a sweater and having it stick to a wall. The Mechanical action displaces some of the electrons on the materials and causes an electrical charge to build up. The different researchers are using thin sheets of partially conductive plastic and small electronic devices to build up these static pulses into something useful, in these cases, lighting an led lamp for a second.

These are very small amounts of energy, but there are a lot of very small and low power devices like rf id chips or wireless sensors that these could power. (Thus the Nano part).

The original article was a purchase article. Here is a (free) article on a similar device for mounting on a window and harvesting similar effects from water droplets running across it :
Highly transparent triboelectric nanogenerator for harvesting water-related energy
http://www.nature.com/srep/2015/150313/srep09080/full/srep09080.html

[OKIsItJustMe]

4. They’re talking about significantly more power here…

https://www.sciencedirect.com/science/article/pii/S2211285515001937

[font face=Serif][font size=5]Single-electrode triboelectric nanogenerator for scavenging friction energy from rolling tires[/font]
[font size=4]…

• This development provides a promising solution to improve fuel efficiency of conventional vehicles or the cruising ability of electric vehicles.

[/font]
[font size=3]Abstract

Triboelectric nanogenerator (TENG) is a novel energy harvesting device to convert mechanical energy into electricity based on the universally known triboelectric principle. In this work, we demonstrated an innovative design of single-electrode TENG (S-TENG) using PDMS to simulate the tire surfaces for scavenging the wasted friction energy from rolling tires. By fixing the PDMS S-TENG on a rubber wheel, the performance of scavenging friction energy was systematically investigated. The electric output of the S-TENG-on-wheel monotonically increased with the increase of the moving speed and weight load of the wheel. The maximum instantaneous power was obtained to be 1.79 mW at a load resistance of 10 MΩ, corresponding to the highest energy conversion efficiency of 10.4%. Multiple S-TENGs were implemented to the tires of a toy vehicle and instantaneously powered 6 commercial green light emitting diodes (LEDs) while the vehicle was moving on the ground. This successful demonstration provides a promising solution to scavenge the wasted friction energy from rolling tires, which may improve the fuel efficiency or the cruising ability of electric vehicles.[/font][/font]

Now, clearly, only a small fraction of a car’s power is lost to rolling friction in the tires.
http://c21.phas.ubc.ca/article/energy-use-cars-3-rolling-resistance

From that, only a fraction can be recovered.

[hr]

Living where I do, one concern I have is that I understand “snow tires” make use of rolling friction to warm themselves, and, to an extent, melt snow from their treads…

[mackdaddy]

5. Maybe they can scale it, but

They are talking about less that 2 milliwatts in this case. That it less that two thousandths of one watt.

It is a long way from any practical drive energy for a vehicle that needs thousands of watts to move, but I could see these as practical for self powering tire pressure monitors.

Good to see basic research continuing. Solar took 50 years to go from Labs to the cheapest form of electricity generation as it is now, if you factor in all external costs of Coal or Nuclear.

[OKIsItJustMe]

6. “They are talking about less than 2 milliwatts in this case.” — for a toy car

From the paper:

… Statistics conducted by the US Department of Energy discovered that 5–7% of energy was consumed by the rolling resistance in vehicles (not including breaking loss) …

The successful development of PDMS S-TENG on wheels for friction energy harvesting suggests it can be an inherent part of a tire owing to the single electrode design. As a demonstration, 6 PDMS S-TENGs (1.5×3.5 cm² each) were attached onto the tire surface of a toy car (each back wheel has 3S-TENGs). …

In summary, we demonstrated an innovative design of S-TENG based on the triboelectric principle using PDMS thin films with a rough surface. The PDMS only has one back electrode for induced charge collection and its front surface is in direct contact with the supporting ground. This single electrode design offers a unique capability for scavenging the otherwise-wasted friction energy between a rolling wheel and the ground. The electric output from the S-TENG-on-wheel increased monotonically following the increase of the moving speed and weight load. By optimizing the load resistance on the external electric circuit, the maximum instantaneous power was found to be 1.79 mW at a load resistance of 10 MΩ, corresponding to the highest energy conversion efficiency of 10.4%. Multiple S-TENGs on the wheel surface can effectively enlarge the number of induced charges, and thus improve the electric output power. Operation of S-TENGs on the wheels of a toy car was also demonstrated. When the vehicle was moving on the ground, the S-TENG generated electricity could instantaneously power 6 commercial green LEDs without any energy storage component. The successful development of PDMS S-TENG demonstrated a promising application capabitliy for scavenging the wasted friction energy between the tires and ground from a running vehicle, and thus improves the fuel efficiency or the total mileage per charge of electric vehicles.

[Nihil]

7. It's not just "snow tires" that will have issues on anything bigger than a toy car.

>> attached onto the tire surface of a toy car

1) Friction wears away the surface.
2) Anything on the surface of a tire/tyre will affect braking performance
(and road adherence in general).

It's still fascinating science though!


PS: Keep having to switch off my internal spell-checker each time I quote "tire" for "tyre"

[OKIsItJustMe]

8. Tyre - ancient Mediteranean port city, right?

I think I must have been English in a previous life (or something.) Many of my ancestors were English, but that doesn’t explain my desire to (for example) put ou’s in words, where an o is sufficient…

[Nihil]

9. Yeah, they knew how to rock 'n' roll over there!

Good to hear that your innate nature still likes to spell things
in a more colourful & neighbourly way than your teacher did!