New Green Energy Could Change the Way We Move

Wood pulp, a common waste material, could allow homeowners and communities to create their own energy by just walking around.

UW–Madison associate professor Xudong Wang, graduate student Chunhua Yao, and their collaborators published the details of this amazing new technology in the journal Nano Energy.

Wood pulp is already a component of many pressed wood products, including flooring. The pulp contains tiny, cellulose nanofibers that, when chemically treated, will produce an electrical charge as they come into contact with untreated nanofibers.

When the treated fibers are embedded in flooring, they are able to produce usable electricity.

Footstep energy has been previously created on a small scale but proved impractical due to the use of expensive and nonrecyclable products, but wood pulp is an abundant waste product from many industries. Wang's new flooring might actually cost less than conventional floorings now in general use.

The power is generated from Triboelectricity, the same phenomenon that naturally produces static electricity on clothing. Wang has spent years testing different materials in an effort to harness this mechanical energy source into an effective triboelectric nanogenerator (TENG).

Triboelectricity falls into a larger green energy research field called "roadside energy harvesting" that could rival solar power in many environments.

Roadside energy harvesting focuses on ways to capture the energy created by usual and everyday human activities.

Using footstep generator flooring in heavy traffic areas like malls or school hallways could generate a significant amount of energy. Unlike solar or water generator technologies, it is not dependent on certain weather conditions.

Similar to solar panels, the flooring has two differently charged materials. Solar moves electrons using the sun's heat, while the new material uses the vibrations caused by walking or running. The electrons naturally want to shift back to correct the charge imbalance, but they must pass through an external circuit to return. That process creates the energy.

Lab tests show the material can last through millions of cycles. It would likely outlast the floor itself.

The patent to the new technology is held by the Wisconsin Alumni Research Foundation. Other authors on the paper include Zhiyong Cai of the Forest Products Laboratory and UW–Madison graduate students Alberto Hernandez and Yanhao Yu. The National Science Foundation and Forest Products Laboratory provided funding for the research.