New super-thin film acts like "air conditioner" for buildings

Engineers at the University of Colorado Boulder have developed a thin, artificially structured “metamaterial” that can cool objects without the use of water or energy. The film works to lower the temperature of the surface beneath it through a process known as “passive cooling,” meaning that it vents the object’s heat through thermal radiation while bouncing off any incoming solar energy that may negate those losses. As described in the journal Science last week, the glass-polymer hybrid material could provide an “eco-friendly means of supplementary cooling” for thermoelectric power plants, which require colossal amounts of water and electricity to keep their machinery chugging along at optimum temperatures.

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The film measures a lithe 50 micrometers thick, or just slightly more substantial than the aluminum foil you’d find in your kitchen. And, much like foil, researchers say it can be easily and economically manufactured by the roll for large-scale residential and commercial applications.

“We feel that this low-cost manufacturing process will be transformative for real-world applications of this radiative cooling technology,” Xiaobo Yin, an assistant professor who co-directed the research, said in a statement.

Buildings and power plants aren’t the only structures that could benefit, Yin said. The material could also keep solar panels from overheating, allowing them to not only work longer, but harder, as well.

“Just by applying this material to the surface of a solar panel, we can cool the panel and recover an additional one to two percent of solar efficiency,” said Yin. “That makes a big difference at scale.”

Yin and his cohorts have applied for a patent as a prelude to exploring potential commercial applications. They also plan to create a 200-square-meter “cooling farm” prototype in Boulder sometime this year.

“The key advantage of this technology is that it works 24/7 with no electricity or water usage,” said Ronggui Yang, a professor of mechanical engineering and a co-author of the paper. “We’re excited about the opportunity to explore potential uses in the power industry, aerospace, agriculture and more.”