By Josh Perry, Editor
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Physicists at The University of Colorado – Boulder turned to local breweries to cultivate beer wort, the waste liquid from the brewing process, and used the cellulose from that liquid to create a mostly transparent, insulating aerogel that could coat windows of habitats in space.

Joshua De La Cruz, a Ph.D. student in the CU Boulder Materials Science and Engineering Program, pours beer wort into a tray before adding cellulose-producing bacteria.
(CU Boulder)

According to an article from the university, transparency is what sets this development apart from other window coatings that have been created because it would allow for sunlight to be collected and the energy stored to protect against the temperature changes on Mars or the moon.

To create the lightweight aerogel, scientists crisscross patterns of solid materials that trap air inside billions of pores. This creates the insulating properties of the gels. To make the gel translucent, UC Boulder researchers use cellulose and create organized, lattice-like patterns that allow light to pass through rather than be scattered.

“Currently, it takes the team about two weeks to culture the cellulose [from beer wort], but the rest of the process of making the aerogel moves quickly,” the article explained. “The final product of the team’s efforts is a thin, flexible film that is roughly 100 times lighter than glass. This gel is so resistant to heat that you could put a strip of it on your hand and light a fire on top—without feeling a thing.”

In addition to the ultimate goal of coating windows of homes on Mars, the aerogel could also be applied to terrestrial windows to improve insulation and lower energy costs. To achieve this goal, researchers are working on improving the speed of aerogel manufacturing.

The research was recently published in Nano Energy. The abstract stated:

“Experimental realization of optically transparent, mechanically robust and flexible aerogels has been a longstanding challenge, which limits their practical applications in energy-saving devices, such as thermally insulating films for enhancing energy efficiency of windows. The poor transparency precluded even hypothetical consideration of the possibility of birefringent aerogels.

“We develop birefringent and optically isotropic aerogels that combine properties of thermal super-insulation, mechanical robustness and flexibility, and transparency to visible-spectrum light. This unusual combination of physical properties is achieved by combining liquid crystalline self-organization of cellulose nanofibers with polysiloxane cross-linking and control of the nanoscale porosity to form hybrid organic-inorganic mesostructured aerogels.

“Potential applications of these inexpensive materials range from single pane window retrofitting to smart fabrics.”

Learn more in the video below: