Scientists Modify Wood and Turn It Into a Mini Generator

Wood can be so much more than "just" a building material.
Fabienne Lang
Spongy woodEMPA

Researchers found a way to chemically modify wood to make it more compressible, and when compressed, it becomes a mini generator. That's right, wood that generates an electrical voltage.

As the researchers from ETH Zurich and Empa in Switzerland said: "Wood is much more than 'just' a building material." Their research focuses on enhancing wood's properties so that it can be used for more applications.

The team's findings mean that such wood could be used as a biosensor or as a building material that harvests energy in the future. 

What the team did to make wood turn into a generator

The team used a chemical, and a biological process in order to turn wood into more of a compressible material that generates an electrical voltage. The team focused on what's called the "piezoelectric effect" of wood to get its results. 

When a piezoelectric material like wood is deformed it generates a low electrical voltage. In order to get a higher voltage out of wood, it has to be chemically changed, which in turn also makes it more compressible. 

To do this, the team dissolved one component of the wood's cell walls: lignin

"Lignin is the stabilizing substance that trees need to grow tall. Without lignin, which connects the cells and prevents the stiff cellulose fibrils from buckling, this would not be possible," explains Ingo Burgert from ETH Zurich.

By chemically removing lignin from the wood, its piezoelectric effect is enhanced as it becomes more pliable. And in doing so, the wood turns into a white, wooden sponge, which is made up of layers of thin cellulose. Once compressed, the sponge shifts back into its original shape.

In doing this, the team managed to generate an electrical voltage 85 times higher than the original wood.

Working on its findings, the team took it one step further by trying and create this electrical voltage from wood without needing to use chemicals to dissolve the cell wall's component. 

They managed to do so with the fungus Ganoderma applanatum that causes white rot in wood and degrades the lignin and hemicellulose naturally. The voltage generated was lower, the researchers said, but this method is more environmentally friendly than using chemicals. 

The team hopes that its findings could be used in future sustainable building materials that are capable of harnessing energy.

There's still more research to be done before we can expect to find such powers in building materials, and in the meantime, the original research is published in ACS Nano, and the follow-up research is in Science Advances.


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