Simple, inexpensive method for creating energy-harvesting wooden floors

Simple, inexpensive method for...
Xudong Wang, from UW-Madison, with a prototype section of the energy-harvesting flooring
Xudong Wang, from UW-Madison, with a prototype section of the energy-harvesting flooring
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Xudong Wang, from UW-Madison, with a prototype section of the energy-harvesting flooring
Xudong Wang, from UW-Madison, with a prototype section of the energy-harvesting flooring

In the smart cities of the not-too-distant future, sidewalks might be able to generate power from the footsteps of pedestrians thanks to companies like Pavegen, but while costs have largely restricted this technology to public spaces like shopping centers – and soccer pitches – a new technique developed at the University of Wisconsin-Madison (UW-Madison) could see homes powered by the same source for around the same price as conventional flooring.

Whereas Pavegen's tiles use electro-magnetic induction to generate electricity, the material developed by the UW-Madison team relies on the triboelectric effect, which creates a charge, most commonly seen as static electricity, through the friction of two materials rubbing against one another. The principle is already being explored for use in clothing and touchscreens that harvest electricity, and the team calls this approach "roadside energy harvesting."

"Roadside energy harvesting requires thinking about the places where there is abundant energy we could be harvesting," says Xudong Wang, lead researcher on the study. "We've been working a lot on harvesting energy from human activities. One way is to build something to put on people, and another way is to build something that has constant access to people. The ground is the most-used place."

Xudong Wang, from UW-Madison, with a prototype section of the energy-harvesting flooring
Xudong Wang, from UW-Madison, with a prototype section of the energy-harvesting flooring

Wang previously trialled a similar system that could harvest energy from the motion of a car's tires. In this case, electricity is generated through cellulose nanofibers less than a millimeter thick, which are embedded into the wooden flooring. Some of these nanofibers are chemically treated, and when they're brought into close contact with the untreated nanofibers through vibrations caused by footsteps on the surface of the material, they produce an electric charge. This can then be harvested to power lighting, charge batteries, or for other household needs, and the system's energy output could be increased by building in several layers.

The nanofibers are relatively low-cost, and since they're embedded in the same wood pulp used in ordinary flooring, the team believes the technology would be priced around the price of a regular wooden floor. It should also be more recyclable and scalable than existing energy-harvesting surfaces, and just as durable as a standard wood floor.

"Our initial test in our lab shows that it works for millions of cycles without any problem," says Wang. "We haven't converted those numbers into year of life for a floor yet, but I think with appropriate design it can definitely outlast the floor itself."

The team is currently optimizing the system in hopes of building a prototype to lay somewhere at the university to demonstrate the technology. Ultimately, the system might find use in other types of flooring as well.

The research was published in the journal Nano Energy.

Source: University of Wisconsin-Madison

Jeff J Carlson
neat idea ... at the end of the day it may harvest as much electricity in a year that you could buy off the grid for a dollar or two ...
All the reporting on these energy harvesting floors never reports on the fundamental point, people don't want their progress impeded, or their car's fuel consumption to rise. Humans don't provide abundant energy, and don't want to walk on spongy floors or feel a drag to their feet. Its not a free lunch
@Jeff J Carlson: More like a couple of cents worth of electricity!
These kinds of ideas are so achingly dumb that any real engineer wouldn't even spend the time to do a back of the envelope estimate of the energy yield.
That said, the human body consumes on the order of 100W. We might spend 10 minutes per day walking our home floor. Let's assume 0.1% of the body's energy is mechanically transferred to the floor. That's 1 watt-minute per day. Assume a conversion efficiency of 1% (most is bound to go in friction). So I will generate 0.01 watt-minute per day of net electricity. Times 365 days/year that's 3.65 watt-minutes, or 0.06 Wh or 0.00006kWh. The retail price of electricity is about $0.25/kWh in Australia. So all my walking will generate 0.0015 CENTS worth of electricity.
If my estimate falls short by a factor of 67,753 then I will generate $1 worth of electricity.
Put this another way: I would guess a disco floor equipped with energy harvesting and packed with 100 hyped up teenagers bopping like mad, you might generate enough power for a few LED lights.
silly.. solar (even inside) would 'harvest' 100 times as much energy for 1/100th the cost, plus not require some silly floor that will be destroyed in a couple years.
Interesting concept, but it's still micro-energy. Wearable clothes which would recharge your phone (which everyone seems to have superglued to their hands nowadays) are a valid use for it, but are we there yet, or is it just enough to add an extra half hour to the talk time? It's good that people are researching all ways to produce power, but something like this would have to last 20 or more years to pay back the cost, and even then, it's iffy. Solar-gathering clothes and floors would be a higher-energy, more usable project.
Shame on you, New Atlas, for publishing something like this without saying how much energy would be created (negligible).