Scientists Develop "Paint" To Help Cool the Planet

AaronW writes Engineers at Stanford University have developed an ultrathin, multilayered, nanophotonic material that not only reflects heat away from buildings but also directs internal heat away using a system called "photonic radiative cooling." The coating is capable of reflecting away 97% of incoming sunlight and when combined with the photonic radiative cooling system it becomes cooler than the surrounding air by around 9F (5C). The material is designed to radiate heat into space at a precise frequency that allows it to pass through the atmosphere without warming it.

Comments

Yes...

[pushing-robot]

Scientists Develop "Paint" To Help Cool the Planet

They're calling it "White".

Seriously, though, it's a mirrored silver paint with some nanoparticles mixed in to make it even cooler (pun intended). But if people aren't painting their roofs white and silver today, do they really think their paint will change that?

On the other hand, a radiator that reflects sunlight sounds promising for other applications, like heatsinks for space probes.

Re:Yes...

[rtb61]

Would people paint their roofs to save money, you bet they will but how cheap is the paint, how clean does the roof need to be, how cheap is it to apply and how long will it last. I would have no qualms about painting my roof white, as long as I can get it done cost effectively enough. Of course one other thing, how well does it perform after it is no longer pristine, how self cleaning is it with rainfall or do I have to get up there and clean it every once a month to maintain performance. When it comes to using white as default for roofs, it is easy enough for many countries to legislate that for all new structures that is mandatory and provide subsidise for existing structures.

-457 farenheit is nothing to sneeze at.

[Ungrounded Lightning]

What the material is doing (or is claimed to do, anyway) is to re-radiate incident radiation at a wavelength that can pass through through the atmosphere back out to space without being absorbed (i.e. it won't heat up the atmosphere).

More importantly: If the wavelength were one that was absorbed by the atmosphere, it is also one where the atmosphere radiates heat back toward the paint.

If your frequency slot is one with "absorption", you "see" the temperature of the atmosphere - a bit cooler than the surface of the (greenhouse-effect boosted) planet, but not by enough to be exciting.

If your slot is one that is essentially fully transparent, you "see" the cosmic background (except for the tiny part of the sky that shows the sun's or moon's disk). That's about 2.7 degrees K, call it -457 Fahrenheit. Liquid helium is substantially warmer at -452.2.

The slow radiation of heat at the sky is almost completely overwhelmed by conductive and other transfers of heat into the paint, of course. Of the 530ish degrees F difference from room temperature, only nine are left.

But that's nothing to sneeze at. The inside of my well-insulated desert house gets up to about 85 in the day without air conditioning. If I could drop that by nine degrees it would be a relatively comfortable 76. (It would likely actually drop more, because the lower temperature of the surface would slow the heating and tend to even the daily cycle of temperature out further.) 85 or more is debilitating. 76, with drastically low humidity (dew point typically about 35), is actually comfy.