Tag Archives: Lars A. Berglund

Enabling a transparent wood battery that stores heat and regulates indoor temperature with lemons and coconuts

i’ve had transparent wood stories here before but this time it was the lemons and coconuts which captured my attention.

Peter Olsén and Céline Montanari, researchers in the Department of Biocomposites at KTH Royal Institute of Technology in Stockholm, say the new wood composite uses components of lemon and coconuts to both heat and cool homes. (Photo: David Callahan) Courtesy: KTH Royal Institute of Technology

From a March 30, 2023 news item on Nanowerk,

A building material that combines coconuts, lemons and modified wood could one day be enough to heat and cool your home. The three renewable sources provide the key components of a wood composite thermal battery, which was developed by researchers at KTH Royal Institute of Technology in Stockholm.

Researchers reported the development in the scientific journal, Small (“Sustainable Thermal Energy Batteries from Fully Bio-Based Transparent Wood”). Peter Olsén, researcher in the Department of Biocomposites at KTH, says the material is capable of storing both heat and cold. If used in housing construction, the researchers say that 100 kilos of the material can save about 2.5 kWh per day in heating or cooling—given an ambient temperature of 24 °C.

KTH researcher Céline Montanari says that besides sunlight, any heat source can charge the battery. “The key is that the temperature fluctuates around the transition temperature, 24 °C, which can of course be tailored depending on the application and location,” she says.

A March 30, 2023 KTH Royal Institute of Technology press release, which originated the news item, describes the roles that lemons and coconuts play,

The process starts with removing lignin from wood, which creates open pores in the wood cells walls, and removes color. Later the wood structure is filled with a citrus-based molecule—limonene acrylate—and coconut based molecule. Limonene acrylate transforms into a bio-based polymer when heated, restoring the wood’s strength and allowing light to permeate. When this happens the coconut molecule are trapped within the material, enabling the storage and release of energy.

“The elegance is that the coconut molecules can transition from a solid-to-liquid which absorbs energy; or from liquid-to-solid which releases energy, in much the same way that water freezes and melts,” Montanari says. But in the transparent wood, that transition happens at a more comfortable 24C

“Through this transition, we can heat or cool our surroundings, whichever is needed,” Olsén says

Olsén says that potential uses include exterior and interior building material for both transparency and energy saving – in exteriors and interiors. The first application of the product would be for interior spaces to regulate temperatures around the 24C mark to cool and to heat. More study is needed to develop it for exterior use.

And it’s not just for homes or buildings. “Why not as a future material in greenhouses?” he says. “When the sun shines, the wood becomes transparent and stores more energy, while at night it becomes cloudy and releases the heat stored during the day. That would help reduce energy consumption for heating and at the same time provide improved growth.”

A close-up look at the material produced in the study. Courtesy: KTH Royal Institute of Technology

Here’s a link to and a citation for the paper,

Sustainable Thermal Energy Batteries from Fully Bio-Based Transparent Wood by Céline Montanari, Hui Chen, Matilda Lidfeldt, Josefin Gunnarsson, Peter Olsén, Lars A. Berglund. Small Online Version of Record before inclusion in an issue 2301262 DOI: https://doi.org/10.1002/smll.202301262 First published online: 27 March 2023

This paper is open access.

Cellulose aerogels for new wood-based composites

‘Frozen smoke’ or ‘solid smoke’ as it’s sometimes described, aerogel fascinates scientists.The latest on cellulose aerogels derived from wood is the focus for a February 14, 2018 Nanowerk Sportlight article by Michael Berger (Note: Links have been removed),

Aerogels, sometimes called frozen smoke, are nanoscale foams: solid materials whose sponge-like structure is riddled by pores as small as nanometers across. They can be made from different materials, for instance silicon.

Aerogels are among the lightest solid substances in the world yet flexible, extremely strong and water repellent, which makes them very interesting materials for engineers.

Cellulose aerogels, made from nanofibrils found in plants, have several unique features, one of which is super high oil absorption capacity that is several times higher than commercial sorbents available in the market.

“Encouraged from our previous work on transparent wood (“Transparent wood for functional and structural applications”; “Optically Transparent Wood from a Nanoporous Cellulosic Template: Combining Functional and Structural Performance”; “Nanostructured Wood Hybrids for Fire-Retardancy Prepared by Clay Impregnation into the Cell Wall”), we started to develop porous wood/epoxy biocomposite materials, which preserves the original hierarchical and porous structure of wood,” Qi Zhou, an associate professor in the Department of Chemistry at KTH Royal Institute of Technology, tells Nanowerk.

“Our strategy is different from traditional wood modification methods,” explains Zhou. “It involves two steps, a simple chemical treatment to remove the lignin (delignification) at first, then back infiltration of the wood cell wall with epoxy, leaving the lumen (a void space) open. In traditional wood polymer composites, both the cell wall and cell lumen are filled with polymer.”

The scientists don’t seem to have any particular applications in mind but they are hopeful that new materials will inspire new uses. Here’s a link to and a citation for Zhou’s latest paper,

Wood Nanotechnology for Strong, Mesoporous, and Hydrophobic Biocomposites for Selective Separation of Oil/Water Mixtures by Qiliang Fu, Farhan Ansari, Qi Zhou, and Lars A. Berglund. ACS Nano, Article ASAP DOI: 10.1021/acsnano.8b00005 Publication Date (Web): February 7, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.