Imagine, you have solar panels on your roof, a wind turbine in your back yard, solar charging windows, and solar and wind charging curtains. What else could you do to charge green energy without hooking up a bicycle to your lamps? The answer is beneath you. Researchers at University of Wisconsin–Madison have found a way to make energy charging flooring.

The research was done mostly by Xudong Wang, associate professor of materials science and engineering, and graduate student Chunhua Yao. The flooring charges energy when it is walked on, so in hallways with a lot of traffic, such as in schools and malls, this could generate a lot of energy.

For the energy charging flooring, the researchers use wood pulp, a common waste material. It is cheap, abundant and renewable. This material is already used in flooring, and consists in part of cellulose nano-fibres. These tiny fibres are treated chemically so that they produce an electrical charge when they come into contact with untreated nano-fibres.

The flooring works as a tribo-electric device, which means that it turns friction into energy. It consists of two layers of a millimetre or less thick that are brought into contact by people walking over it. For a higher energy output, more layers could be added.

The energy is created by electrons that move from one to the other material based on their different electron affinity. The transfer causes an imbalance that wants to right itself, but as the electrons return, they pass through an external circuit.

The flooring has enough energy to power the lights and other low electricity consuming products in a house. It is not entirely clear how much you have to walk to make that happen, however.

While the flooring has not been put into use yet, lab testing shows that it works for millions of cycles without a problem. The researchers estimate that the material will outlast the floor itself.

Compared to solar and wind energy, the advantage of energy charging flooring is clear: the flooring is not dependent on the weather, only the amount of feet that pass over it. In addition, because wood pulp is so cheap, as is the chemical process, the electric charging flooring would not cost much more than normal flooring.

Next (foot)step in the process is to build a high-scale prototype.