An innovative technology by engineers at Stanford functions like an air-conditioning system, but it is made of nanostructured photonic materials. The so-called “passive solar radiator” can cool any building even when the sun is shining brightly.
According to the researchers, who published a study in the latest issue of Nano Letters, the system can be used in any man-made structures.
As stated by Shanhui Fan, a professor of electrical engineering and the paper’s lead author, the reflector should not absorb any sunlight, while the structure should be efficient enough to radiate heat back into space, emitting energy in a specific wavelength range.
To meet both of these requirements, the team engineered a broadband mirror for sunlight, which acts as a reflector and emits thermal radiation efficiently. This was made possible through the engineering of new nanostructured photonic materials.
The innovation, according to Aaswath Raman, a doctoral candidate in Fan’s lab and a co-first-author of the paper, this is the first time anyone has combined both the emitter and the reflector in one device.
Using the device, the team was able to achieve as much as 100 watts of net cooling power per square meter. The device is not only fully functional, but it also does not require an external energy source to operate.
The team is convinced that the technology could be used practically anywhere, saving energy and cooling buildings and cars effectively.