Scientists have developed a transparent heat-resistant gel using beer waste that may one day be used to build greenhouse-like habitats for human colonised on Mars.
The "aerogel," which looks like a flattened plastic contact lens, could also be used on buildings on Earth to help make huge savings on energy costs. The "aerogel," is so resistant to heat that you could put a strip of it on your hand and a fire on top without feeling a thing, researchers said. However, unlike similar products on the market, the material is mostly see-through.
"Transparency is an enabling feature because you can use this gel in windows, and you could use it in extraterrestrial habitats," said Ivan Smalyukh, a professor at University of Colorado at Boulder (CU Boulder) in the US. "You could harvest sunlight through that thermally-insulating material and store the energy inside, protecting yourself from those big oscillations in temperature that you have on Mars or on the moon," said Smalyukh.
The group's gel is also cheaper to produce because it comes from beer waste. Aerogels are at least 90 per cent gas by weight, but their defining feature is air. Their thin films are made up of crisscrossing patterns of solid material that trap air inside billions of tiny pores, similar to the bubbles in bubble wrap. It is that trapping capacity that makes them such good insulators. Most currently available aerogels, however, are opaque.
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To make a different type of gel, researchers began with the common plant sugar cellulose. By carefully controlling how cellulose molecules link up, the team is able to orient them into a lattice-like pattern. That pattern is so uniform that it allows light to pass through unbothered, giving the gel its transparent appearance.
Researchers can make cellulose by adding specialized bacteria to a wide range of food waste. The team has been driving to breweries across the Boulder area to collect tubs of beer wort, or the waste liquid produced during the brewing process.
"So not only are we recycling and saving this valuable material from entering the landfill, but we're also producing this raw material cheaply," said Andrew Hess, a PhD student at CU Boulder.
The final product of the team's efforts is a thin, flexible film that is roughly 100 times lighter than glass. Researchers envision a peel-and-stick film that would available at departmental stores and could simply be attached to home windows. "Our approach so far has been around windows," Hess said. "However, we also see our technology being enabling for so many other applications, including smart clothes, for insulating cars and protecting firefighters," he said.