Found a new way to get energy from walking

Scientists from the University of Wisconsin-Madison have come up with a simple and inexpensive way to transform walking into useful electricity. Xudong Wang and his colleagues invented material that generates electricity when people step on it.

The new method finds a good use for such fiber semi-finished product as wood pulp . The ground wood, which is already in the floor covering, is partially made of cellulose nanofibers. They are tiny fibers that, after a certain chemical treatment, are capable of forming an electrical charge when they come into contact with the untreated ones. Xudong Wang, assistant professor of materials science and engineering at the University of Wisconsin-Madison, and his graduate student Chunhua Yao published their work at Nano Energy on September 24th.

When nanofibers are embedded in the floor, they can generate electricity that turns on the lights and charges the batteries. Since wood pulp is a cheap, widespread and renewable waste from many industries, the new technology can be just as affordable as conventional floor materials.

To do this, the researchers extracted the nanofibers of cellulose from wood pulp and divided them into two layers, one of which was chemically treated to make it positively charged. Then they encased both layers in cardboard and pressed them to make a hard board.

Under pressure from the legs, the two layers of cellulose come into contact and exchange electrons. When the leg rises, the electrons return, but pass through the external circuit, producing energy. One step on such a surface generates from 10 to 30 volts and can light up 35 green LEDs.

There are other similar materials for the generation of "stepped" energy - ceramics and metals. But they are either expensive, or unsuitable for reuse, or impractical for large scale use.

For years, the Van Research Center has tested various materials to maximize the benefits of a technology called triboelectricnanogenerator (TENG). It is due to the triboelectric effect that static electricity is generated on clothing. Chemically treated nanofibers of cellulose is a simple, inexpensive, and effective alternative to using this widespread mechanical energy source.

The scientist believes that TENG technology can be easily incorporated into all types of flooring as soon as it is ready for sale. The Van team now plans to build and test a prototype on the campus of the University of Wisconsin-Madison in places with a large flow of people. Ultimately, they are going to propose using green floorboards at train stations and in shopping centers where they could power the lights and sensors.

The result of the University of Wisconsin-Madison team is the latest achievement in the field of environmental and renewable energy research, called “roadside energy collection”. In some situations, it could compete with solar energy, since it does not depend on fair weather. Researchers who study roadside methods of collecting and converting incidental energy see the earth as a rich, renewable source of energy, despite limited fossil fuel reserves.

“Scientists have worked hard to collect energy from human activity. One way is to build something to put people in there. Another way is to build something that people have constant access to. The earth is the most suitable place, ”argues the scientist.

If you use this technology in areas of heavy traffic, for example, in stadiums or in shopping centers, we will get a significant amount of energy. Each functional part inside such a coating consists of two materials with a different charge, including cellulose nanofibres one millimeter thick or even thinner. The floor may consist of several layers in order to get more energy at the exit.

“The first test in our laboratory showed that the technology works on millions of cycles without any problems,” says Wang. We didn’t convert these figures into the life of the flooring, but I think that with the proper design, TENG will easily survive it (flooring). ”

Despite all the clear benefits of green technology, some scientists were skeptical about Van's design. Alistair Sproul from the University of New South Wales in Sydney believes that, compared with other sources of renewable energy, the new material yields a very small amount of energy. “If you want to power society and make things efficient, go for solar or wind energy,” he says.

Wang believes that the energy of steps can serve as an addition to solar. “The concept is to generate electricity from energy that could be wasted. It works inside buildings or underground where the sun's rays do not penetrate or are too few, ”he notes.

Now the team led by Wan will try to prove that the new boards are durable and cost-effective. The cost of production of "energy" boards is almost the same as usual. However, additional costs are required to replace the existing coverage and install a new one.

“Our technology cannot replace the collection of solar energy. But we believe that its use as a supplement will be the most cost-effective compared to other technologies that derive energy from steps. ”