United States.
A company founded by Stanford University researcher Aaswath Raman has developed a cooling method capable of expelling excess heat from the atmosphere in the form of infrared rays.
The idea is to exploit a natural phenomenon called radiation cooling. All objects emit thermal radiation. When emitted into the sky, a part is absorbed and reflected by the atmosphere. The other, which corresponds to a specific range of frequencies, escapes into the upper atmosphere and outer space, where conditions are much colder. This can cause the object to emit that radiation to cool down to below the temperature of the surrounding air.
SkyCool is developing a technology to exploit this phenomenon, based on recent advances in our ability to manipulate light at the nanoscale. Engineers have long known that radiation cooling is useful for cooling buildings at night. During the day, however, the sun's radiation counteracts the cooling effect. But a couple of years ago, Raman and a colleague from Stanford University calculated that it should be possible to achieve a cooling effect by day.
In 2014, the group published a paper on a device designed to combine the optical properties of three distinct materials, arranged in a multi-layer stack and cooled to nearly 5°C below room temperature. This showed that "the cold darkness of the Universe" can be employed as a renewable resource, "even during the hottest hours," the researchers wrote.
An existing model for SkyCool's basic approach, he explains, is the recent development and commercialization of techniques to apply optical cladding to make windows more energy efficient.
Raman explains that the company has also shown that its prototypes can significantly reduce water temperature, suggesting that it should be possible to "plug it into a wide range of existing cooling or air conditioning systems."
Source: MIT Technology Review.
