WEBVTT - How Could the World's Whitest Paint Fight Climate Change? 0:00:01.920 --> 0:00:06.440 Welcome to brain Stuff, a production of iHeart Radio, Hey 0:00:06.480 --> 0:00:10.480 brain Stuff Lauren Vogel bomb Here at noon on a 0:00:10.560 --> 0:00:14.240 sunny summer day, the temperature of a conventional dark colored 0:00:14.240 --> 0:00:17.599 flat roof can reach a hundred and fifty degrees fahrenheit 0:00:17.720 --> 0:00:20.479 that's sixty five degrees celsius, according to the U. S 0:00:20.520 --> 0:00:24.279 Department of Energy, and that heat will warm the inside 0:00:24.280 --> 0:00:26.960 of the building or home as well, making it more 0:00:27.000 --> 0:00:29.960 likely that the occupants will turn to air conditioning, an 0:00:30.080 --> 0:00:33.919 energy expenditure that often requires burning fossil fuels at electrical 0:00:33.920 --> 0:00:38.280 power plants, whose emissions contribute to the progression of climate change. 0:00:39.000 --> 0:00:43.240 It's a bedeviling problem that might easily be solved if 0:00:43.320 --> 0:00:46.800 we only had roofs that reflected solar energy back into 0:00:46.800 --> 0:00:51.280 the sky instead of absorbing it. It's a deviling problem 0:00:51.440 --> 0:00:54.280 that might be easily solved if we could only have 0:00:54.520 --> 0:00:58.200 roofs that reflected solar energy back into the sky instead 0:00:58.240 --> 0:01:02.800 of absorbing it. That's why researchers development of the whitest 0:01:02.880 --> 0:01:06.560 paint ever created an ultra white formulation that reflects up 0:01:06.560 --> 0:01:09.720 to nine point one percent of sunlight could turn out 0:01:09.760 --> 0:01:11.600 to be a really big deal in the effort to 0:01:11.640 --> 0:01:14.800 reduce energy consumption and combat the warming of our planet. 0:01:15.880 --> 0:01:19.720 The breakthrough is detailed in April issue of Applied Materials 0:01:19.760 --> 0:01:24.520 and Interfaces, an American Chemical Society journal, and not only 0:01:24.600 --> 0:01:27.840 does the paint absorb very little energy from sunlight, but 0:01:27.920 --> 0:01:31.119 it also emits thermal energy in the infrared range back 0:01:31.160 --> 0:01:34.040 into the atmosphere so that it travels out and away 0:01:34.080 --> 0:01:37.960 from Earth before the article. This episode is based on 0:01:38.120 --> 0:01:40.680 how Stuff Works. Spoke by email with Zen You Lee, 0:01:41.080 --> 0:01:44.480 the paper's first author. He's a postdoctoral researcher at the 0:01:44.560 --> 0:01:47.960 Massachusetts Institute of Technology who worked on the project while 0:01:47.960 --> 0:01:52.080 in graduate school at Purdue. He said this paint not 0:01:52.160 --> 0:01:55.280 only reflects the majority of the sunlight to avoid overheating, 0:01:55.600 --> 0:01:59.000 but also cools itself down colder than the air surrounding 0:01:59.040 --> 0:02:03.120 it even under direct sunlight. In some way, it's effectively 0:02:03.200 --> 0:02:09.040 an air conditioner without consuming any electricity. Researchers have been 0:02:09.040 --> 0:02:11.600 trying to make paints that could be used in passive 0:02:11.600 --> 0:02:14.680 cooling since the nineteen seventies, but most of them have 0:02:14.760 --> 0:02:18.160 absorbed too much sunlight, so they don't provide any cooling 0:02:18.160 --> 0:02:22.520 effect in the daytime. Lee explained, in recent years, scientists 0:02:22.520 --> 0:02:27.080 have also been exploring exotic technologies for creating light reflecting surfaces, 0:02:27.120 --> 0:02:31.400 such as multi layered nanostructured films, but those solutions tend 0:02:31.400 --> 0:02:36.120 to be expensive and not easily scalable to buildings. That 0:02:36.200 --> 0:02:38.760 brought this team of researchers back to thinking that the 0:02:38.800 --> 0:02:42.520 best approach might be a particle polymer composite similar to 0:02:42.600 --> 0:02:47.520 commercial paint. Ordinary white paint isn't quite white enough to 0:02:47.720 --> 0:02:51.480 help much with passive cooling. It only reflects eight of 0:02:51.520 --> 0:02:55.840 sunlight and actually gets warmer from absorbing ultraviolet light, and 0:02:55.960 --> 0:02:58.760 so the task became finding a way to make white 0:02:58.760 --> 0:03:02.840 paint even whiter, and that turned out to be a challenge. 0:03:03.240 --> 0:03:07.040 Alice said. We first tried multiple materials with high electron 0:03:07.120 --> 0:03:11.440 band gap to avoid solar absorption. However, the paints often 0:03:11.440 --> 0:03:14.919 appeared semi transparent at low thickness due to the lack 0:03:14.960 --> 0:03:18.920 of ability to reflect sunlight. During our previous studies on 0:03:18.960 --> 0:03:23.120 commercial paints and theoretical modeling, we identified that both high 0:03:23.120 --> 0:03:28.120 concentration and broad particle size distribution were beneficial. As we 0:03:28.160 --> 0:03:31.640 implemented these two approaches, we saw the paint solution appere 0:03:31.680 --> 0:03:36.800 wider compared to previous attempts, they landed on burying sulfate 0:03:36.880 --> 0:03:39.440 as a way to make the paint very reflective and 0:03:39.680 --> 0:03:43.400 thus very white. You may have heard of burying sulfate before. 0:03:43.720 --> 0:03:45.920 It's the stuff that medical patients take in drink or 0:03:45.960 --> 0:03:49.560 tablet form to code the esophagus, stomach, and intestines when 0:03:49.600 --> 0:03:52.480 they're getting an X ray exam or CT scan, so 0:03:52.560 --> 0:03:55.800 the doctors can see diseased or damaged areas more clearly. 0:03:56.520 --> 0:04:00.400 As a paint ingrediently notes it's already widely available safe 0:04:00.440 --> 0:04:05.200 for humans and the environment. The researchers used a variety 0:04:05.280 --> 0:04:08.040 of sizes of barry and sulfate particles in the paint, 0:04:08.320 --> 0:04:12.320 which enabled the paint to scatter more of the spectrum. 0:04:12.480 --> 0:04:14.280 They also had to make sure that the paint would 0:04:14.320 --> 0:04:17.440 last long enough outside to be suitable for painting rooftops. 0:04:18.040 --> 0:04:22.279 Lee explained, we tested the abrasion resistance, three week outdoor weathering, 0:04:22.440 --> 0:04:26.040 and a water rinse test. All three showed promising results 0:04:26.080 --> 0:04:29.880 as initial durability tests. We also tested the viscosity and 0:04:29.960 --> 0:04:32.599 the paints can be brushed and dried very similar to 0:04:32.720 --> 0:04:36.880 commercial paint. It can also be fabricated in a similar way. 0:04:37.040 --> 0:04:39.360 In this work, we not only achieved a paint that's 0:04:39.360 --> 0:04:42.599 superior to the commercial paint, but also do not need 0:04:42.680 --> 0:04:46.799 specialized equipment or materials to fabricate, transport, or apply the paint. 0:04:48.839 --> 0:04:51.839 The ultra white paint looks pretty similar to regular white 0:04:51.839 --> 0:04:56.039 paint because the difference in reflectivity, while significant in terms 0:04:56.040 --> 0:05:00.880 of cooling, is imperceptible to humanize. The next step in 0:05:00.920 --> 0:05:03.400 the research is to optimize the paint for long term 0:05:03.480 --> 0:05:07.000 durability under different sorts of weather conditions, but there isn't 0:05:07.080 --> 0:05:08.919 yet a target date for it to be market ready, 0:05:09.080 --> 0:05:11.159 so don't search for it at your local hardware store 0:05:11.279 --> 0:05:19.080 just yet. Today's episode is based on the article the 0:05:19.080 --> 0:05:22.839 whitest paint Ever produced could save energy climate change on 0:05:22.880 --> 0:05:25.440 how stuff works dot com, written by Patrick J. Keiger. 0:05:25.880 --> 0:05:28.200 Brain Stuff is production of I Heart Radio in partnership 0:05:28.200 --> 0:05:29.960 with how stuff works dot com, and it is produced 0:05:30.000 --> 0:05:33.200 by Tyler clang. Or more podcasts my heart Radio, visit 0:05:33.240 --> 0:05:36.040 the iHeart Radio app, Apple Podcasts, or wherever you listen 0:05:36.120 --> 0:05:37.080 to your favorite shows.