A team of researchers from Nanjing Forestry University in China has developed a dust-resistant, nanocellulose-based, aerogel film radiative cooler.

The researchers — operating upon the understanding that cellulose demonstrates high emissivity within the atmospheric transparency window (λ≈ 8–13 µm) — have identified the material as a potential candidate for radiative cooling. However, the researchers also report that traditional cellulose-based cooling systems tend to be lacking in terms of solar reflectivity as well as susceptible to external dust contamination, thus resulting in reduced daytime cooling efficiency.

he scheme for passive cooling based on nanocellulose radiative cooler. Source: Cai, C. et al

As such, the Nanjing Forestry University team has created a nanocellulose aerogel film to serve as a passive cooling material. According to its developers, the new nanocellulose aerogel film offers powerful solar scattering and infrared emissivity, subsequently making the material highly effective for passive cooling during the summer months.

"The scalability of the nanocellulose aerogel film is achieved through freeze-drying and hot-pressing techniques. This pioneering cellulosic cooling solution can deliver a sub-ambient temperature reduction of 6.9° C under direct sunlight in hot conditions while also exhibiting dust-repellent properties," explained the researchers.

The team’s findings are detailed in the article, “Large scalable, ultrathin and self-cleaning cellulose aerogel film for daytime radiative cooling,” which appears in the Journal of Bioresources and Bioproducts.