Photo Caption: Associate Professor Xudong Wang holds a prototype of the researchers’ energy harvesting technology, which uses wood pulp and harnesses nanofibers. The technology could be incorporated into flooring and convert footsteps on the flooring into usable electricity. (Credit: Stephanie Precourt, Digital Media Manager at University of Wisconsin-Madison.)
For decades, researchers have been looking up to try to harness wind and solar energy when maybe they should have been looking down.
Xudong Wang, an associate professor of materials science and engineering at University of Wisconsin-Madison, said he has developed a method of harnessing wood pulp, a common component of flooring, as an inexpensive and simple method of producing useable green energy.
Wang and his team is the latest to advance the green-energy research field, being dubbed “roadside energy harvesting,” that could rival solar power because it doesn’t depend on a variable like the weather.
“Roadside energy harvesting requires thinking about the places where there is abundant energy we could be harvesting,” Wang said in a statement. “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,” he added. “The ground is the most-used place.”
Wood pulp is partly made of cellulose nanofibers, which are tiny fibers that when chemically treated produce an electrical charge when they come into contact with untreated nanofibers.
Nanofibers can be embedded within flooring to produce electricity that can be harnessed to power lights or charge batteries.
According to Wang, once the treated and untreated nanofibers combine, the electrons move from one to another based on their different electron affinity and this transfer creates a charge imbalance that pass through an external circuit and creates the energy.
Wang estimates that heavy traffic floors in hallways and places like stadiums and malls could produce significant amounts of energy if the new technology is incorporated by constructing the floor with several layers of cellulose nanofibers, which can be less than a millimeter thick.
While other attempts to harness footstep energy have been deemed too costly, unable to be recycled and impractical at a large scale, this research centers around using vibration to generate electricity.
Wang has been testing different materials in an effort to maximize the merits of a triboelectric nanogenerator (TENG), an energy-harvesting device that converts mechanical energy into electricity.
Wang said the technology could be easily incorporated into different kinds of flooring once it is ready for the market. In the meantime, he is optimizing the technology and plans on building an educational prototype in a high-profile location at the UW-Madison campus where he can better demonstrate the concept.
“Our initial test in our lab shows that it works for millions of cycles without any problem,” Wang added. “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.”
Wang, a graduate student Chunhua Yao and other contributors published the details of the study in the Sept. 24 issue of Nano Energy.
The Wisconsin Alumni Research Foundation holds the patent to the technology. Other authors on the paper include Zhiyong Cai of the Forest Products Laboratory and UW–Madison graduate students Alberto Hernandez and Yanhao Yu. The Forest Products Laboratory and National Science Foundation provided funding for the research.
