TIL 35: “What’s your electricity bill this summer? Mine’s zero.”

Today I learned that MIT created a system that provides cooling with no electricity whatsoever.

It was tested in a blazing hot Chilean desert and achieved a cooling of 13C compared to the hot surroundings

How did it do that? The answer lies in a material called aerogel.

Aerogel is an extremely lightweight material made out of polyethylene foam- the same thing used to make plastic bags. It’s extremely light and contains almost 99.8% air-think of it like a jelly but with more air instead of liquid.

The material is an excellent insulator, with an excellent ability to block and reflect all the visible rays of sunlight trying to penetrate through it.

In fact, not only is it a great insulator but also has this special quality of being highly transparent to the infrared rays that carry heat. This allows the rays to pass freely outward of the material and into space, thereby reducing the temperature of the substance inside.

This phenomenon is something called Radiative Cooling. Radiative cooling is simply the main process that most hot objects use to cool down. They emit midrange infrared radiation, which carries the heat energy from the object off into space using air as a medium- which, of course, is highly transparent to infrared radiations.

And this new device, designed by MIT graduate student Arny Leroy along with several other MIT professors, uses Aerogels and the principle of radiative cooling to create a completely electricity-free cooling mechanism.

They took a real-world test of the device in Chile’s Atacama desert, parts of which are the driest land on Earth. The device achieved a cooling of 13 degrees Celsius under full sunlight at solar noon.

Theoretically, according to Wang, the device is capable of achieving temperature cooling of up to degrees Celsius.

Further optimizations could help be expanded to other cooling applications such as building air conditioning without the need for any source of power.

Although aerogels are extremely fragile and hence cannot be commercialized much if tweaked the material could potentially help build inexpensive cooling and heating mechanisms around the world.

https://news.mit.edu/2019/system-provides-cooling-no-electricity-1030

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