Since it was first introduced in 2016, transparent wood has been developed by researchers at KTH Royal Institute of Technology as an innovative structural material for building construction. It lets natural light through and can even store thermal energy.

The key to making wood into a transparent composite material is to strip out its lignin, the major light-absorbing component in wood. But the empty pores left behind by the absence of lignin need to be filled with something that restores the wood’s strength and allows light to permeate.

In earlier versions of the composite, researchers at KTH’s Wallenberg Wood Science Centre used fossil-based polymers. Now, the researchers have successfully tested an eco-friendly alternative: limonene acrylate, a monomer made from limonene. They reported their results in Advanced Science.

“The new limonene acrylate it is made from renewable citrus, such as peel waste that can be recycled from the orange juice industry,” says lead author, PhD student Céline Montanari.

An extract from orange juice production is used to create the polymer that restores delignified wood’s strength and allows light to pass through.