Scientists have taken another step towards tackling the climate crisis, this time by creating incredibly white paint that reflects sunlight and radiating infrared heat through Earth’s atmosphere into space. Researchers say the paint could become available within a couple years.
The paint is the whitest to ever be created, and was designed to help keep buildings cool—thus eventually eliminating the need for air conditioning and carbon emissions caused by the conditioners. In tests, the paint reflected 98% of sunlight and cooled surfaces by 4.5 degrees Celsius below the ambient temperature even on super sunny days. Eventually, this paint would be applied to the roofs of homes and businesses.
“Our paint can help fight against global warming by helping to cool the Earth—that’s the cool point,” stated Professor Xiulin Ruan at Purdue University. “Producing the whitest white means the paint can reflect the maximum amount of sunlight back to space.”
Painting roofs white isn’t a new thing—cities and cultures around the world have been using that technique to keep buildings comfortably cool for centuries. However, no comparably white paints that are currently available do as good of a job reflecting; they typically average around 80-90% of sunlight reflected and UV light absorption. What that means is that, unlike this new white paint, those paints are unable to cool below the ambient temperature. Ruan shared that applying the new paint to a 93-square-meter roof (1,000 square feet) would create a cooling power of 10 kilowatts, which is “more powerful than the central air conditioners used by most houses.”
The paint was first revealed in a report from the ACS Applied Materials & Interfaces journal, and stated that three factors are responsible for the paint’s ability to cool. First, the pigment is made up of barium sulphate, which does not absorb UV light. Second, the paint uses a high concentration of the pigment: 60%. Third, the pigment particles included are of various sizes. What’s impressive about that is that the quantity of light that can be scattered by a particle depends on its size, so using a range of sizes (rather than a uniform size) scatters more.
With its barium sulphate composition, the paint is able to radiate infrared heat at a wavelength that is not absorbed by air. Ruan said that “The radiation can go through the atmosphere, being directly lost to deep space, which is extremely cold.” He also stated that the paint reflects light diffusely, so it doesn’t appear much brighter than snow and won’t hurt our eyes.
A patent is now being filed for the paint, and is currently working towards large-scale commercialization. If everything goes smoothly, it could become available in as little as one or two years. Though there are logistical issues with acquiring and producing such high levels of barium, the technology would go a long way towards positively impacting global warming.
via The Guardian