Scientists invent transparent wood that stores, releases heat

Scientists have invented a transparent wood, a building material that stores, releases heat, and potentially save energy cost. 

The new material may be the future of energy-efficient homes, as energy captured from the sun during the day can be used to light up home interior at night.

“We prepared a material that is multi-functional – it can transmit light very well and also it can store heat. We combined these two functions in a single material,” said Céline Montanari, a researcher at the KTH Royal Institute of Technology in Stockholm.

The research started 3 years ago when Lars Berglund, a professor and his colleagues at KTH Royal Institute of Technology in Stockholm designed an optically transparent wood.

The transparent wood was made by removing lignin, a component that gives wood colour and strength, from basal wood; and filling the wood with acrylic, a non-biodegradable and water repellent.

As the research progresses, the scientists introduced polyethylene glycol (PEG) to the material.

Polyethylene glycol  is a substance which absorbs heat and melts when heated. It also releases energy whenever there’s a fall in temperature.

“If you take 100g of this transparent wood material with the (polyethylene glycol) inside, it can absorb up to 8,000 joules of heat, which corresponds to basically what a 1 watt (bulb) could produce in two hours,” Montanari said.

“During a sunny day, the material will absorb heat before it reaches the indoor space, and the indoors will be cooler than outside…And at night, the reverse occurs — the PEG becomes solid and releases heat indoors so that you can maintain a constant temperature in the house.”

Though this is not the first attempt to design building materials that can absorb heat and transmit light, the researchers maintained that their invention stands out because of its unique materials.

Montanari added that plans are underway to replace acrylic with a biodegradable alternative, scale up production of the material, and design computer models of building to compare transparent wood with glass.

The researchers are expected to present their results on Wednesday, April 3, 2019 at the American Chemical Society (ACS) spring 2019 national meeting and exposition in Orlando, Florida.