Researchers at KTH Royal Institute of Technology in Sweden developed a sturdy transparent wood material that is able to store and release heat.

The transparent wood material was first reported on in early 2016 (read more here). The material is made by firstly stripping the lignin from the wood. Lignin provides firmness to the material, but it also blocks the light. Once the lignin is removed, the remaining material turns white. By inserting acrylic into the wood, it turns transparent, with a similar look of plexiglass, but much stronger.

In the new research, the acrylic was mixed with a substance called polyethylene glycol, which is non-toxic and biodegradable. This material melts when heated, absorbing energy, and when the temperature falls, it hardens, releasing energy. When integrated into the wood, the material goes from semi-transparent to transparent when warmed.

According to the researchers, if the transparent wood is integrated in the construction of buildings, these could become more energy efficient. The energy from the sun is captured during the day, and slowly released when the temperature drops. 100 grams of the transparent material can absorb up to 8000J of heat, the same a 1W bulb produces in two hours.

The next step in the research is developing a biodegradable version of the transparent wood by replacing the acrylic.

Photo: Wallenberg Wood Science Center