FootfallEnergy

New flooring at the Union South can harness the energy of footfalls.

Photo by ERIK LORENZSONN

The new wooden flooring by the Orchard Street entrance of the University of Wisconsin-Madison Union South isn’t part of a snazzy building redesign.

It’s there for science.

When pedestrians walk over the 96-square-foot installation introduced to the building last week, it collects power from their footfalls. Xudong Wang, a materials science and engineering professor with the university, said the prototype is an example of “roadside energy harnessing” — a type of renewable energy generation that could become a significant part of how we power our society in the future.

The premise of roadside energy is simple: Take recurring mechanical energy that already exists — for example, the energy of a car moving over a road, of a train barreling down a track, or of a UW student walking into Union South to get a slice of pizza — and collecting it. According to Wang, it's not anything that could match the scope of other traditional means of energy generation. However, it could help power electrical installations on a smaller scale.

“The energy is less, but it has all the application potentials for lighting on the roadside or for sensor networks," said Wang.

Collecting energy through flooring is not a new idea. However, Wang said the new flooring at the Union South approaches the concept from a new angle. Other energy-harnessing floors have used magnetic fields to power underground generators.

"Those are pretty complicated. You could imagine having a generator under each floor, it could get very expensive," said Wang.

The Union South flooring relies on "triboelectricity" — in other words, an electrical charge generated by friction. When a person walks over the floor, layers of recycled wooden pulp within the floor panels rub together, creating an electrostatic charge.

"It’s the same as the electrostatic charge on our clothes or on our hands on a dry day," said Wang.

That energy transfers to a circuit, which powers a small sign explaining what the prototype is. The goal of the experiment is to measure foot traffic patterns and energy generation in a real-world environment. Wang also hopes to see how the materials hold up when factors like natural wear and humidity are at play.

Wang said that innovative flooring is just one facet of roadside energy harnessing that his team of engineers are working on. They're also working on nanogenerators that could collect energy from things like rolling tires.

Nanogenerators also have the potential to harvest biomechanical energy, said Wang: Through implants, it could become possible to collect energy from the beating of a heart, the expansion and contraction of a lung, or the movement of muscle.

Erik Lorenzsonn is the Capital Times' tech and culture reporter. He joined the team in 2016, after having served as an online editor for Wisconsin Public Radio and having written for publications like The Progressive Magazine and The Poughkeepsie Journal.