WEBVTT 00:00:00.000 --> 00:00:04.100 We are running out of sand. That sounds insane. 00:00:04.100 --> 00:00:08.480 There are massive deserts all around the world that are just full of sand. 00:00:08.480 --> 00:00:12.160 27.7% of the Earth's crust is just silicon, 00:00:12.160 --> 00:00:17.960 a key component of silica sand. The problem is that not all sand is created equal 00:00:17.960 --> 00:00:23.000 and we use a lot of it. Over 50 billion tons of sand and gravel 00:00:23.000 --> 00:00:26.200 are used globally every year in paving and construction 00:00:26.200 --> 00:00:30.680 but also in Windows, screens, silicon chips and photovoltaic cells. 00:00:30.680 --> 00:00:34.440 And this massive sand demand has been going on for a long time. 00:00:34.440 --> 00:00:38.520 A 2014 UN report estimated that sand was 85% 00:00:38.520 --> 00:00:41.920 of all material mined globally by weight. 00:00:41.920 --> 00:00:45.440 Sand is formed by the gradual erosion of rocks 00:00:45.440 --> 00:00:49.640 into smaller and smaller grains. This is a process that takes thousands of years, 00:00:49.640 --> 00:00:54.280 making sand a renewable resource only in a very technical sense. 00:00:54.280 --> 00:00:58.240 Plus, that sand has different properties depending on how it was created. 00:00:58.240 --> 00:01:03.680 Concrete typically uses water-weathered sand because the resulting grains are rough and angular, 00:01:03.680 --> 00:01:07.920 which allows them to lock together. Wind-weathered desert sand, on the other hand, 00:01:07.920 --> 00:01:13.000 tends to be too round and smooth. Therefore, Dubai, despite being built on a desert, 00:01:13.000 --> 00:01:16.880 imports hundreds of millions of dollars of sand each year 00:01:16.880 --> 00:01:20.640 to support its rapid growth. As for the screen in front of you 00:01:20.640 --> 00:01:24.760 and the silicon chips inside your device, that's a slightly different story. 00:01:24.800 --> 00:01:28.320 Glass needs to be made from near-pure silica sand, 00:01:28.320 --> 00:01:31.840 sand that is at least 95% silicon dioxide, 00:01:31.840 --> 00:01:36.960 or your window is going to look just awful. It also needs to be extremely fine 00:01:36.960 --> 00:01:41.800 with grains between 0.075 millimeters and 1.18 millimeters, 00:01:41.800 --> 00:01:45.800 and it also has to be the right color. For more sophisticated industrial purposes, 00:01:45.800 --> 00:01:49.960 silica is extracted from rock quartz and quartz-rich sand, 00:01:49.960 --> 00:01:54.640 then purified into 98% pure metallurgical-grade silicon. 00:01:54.640 --> 00:01:58.640 Silicon for semiconductors needs to have a purity of 11 nines. 00:01:58.640 --> 00:02:02.840 That's 99% a decimal and nine more nines. 00:02:02.840 --> 00:02:06.160 The advantage of this process is that the geometry of the sand 00:02:06.160 --> 00:02:09.880 doesn't actually matter all that much, so desert sand can be used. 00:02:09.880 --> 00:02:14.840 That being said, natural sources of sand vary a lot in terms of composition, 00:02:14.840 --> 00:02:20.040 and easily accessible quartz-rich sand sources are still a limited resource. 00:02:20.040 --> 00:02:23.040 The global demand for sand is so intense 00:02:23.040 --> 00:02:26.600 that the industry has attracted attention from organized crime, 00:02:26.600 --> 00:02:31.520 and you know the situation is getting serious when a bunch of gangsters roll up and steal a beach. 00:02:31.520 --> 00:02:36.280 Sure, it sounds funny, but illicit sand mining can cause serious problems. 00:02:36.280 --> 00:02:39.400 Not only can intensive dredging of sand from rivers 00:02:39.400 --> 00:02:45.200 and the ocean floor damage local ecosystems, but irresponsible sand mining can erode supports 00:02:45.200 --> 00:02:49.400 from nearby structures and has resulted in multiple fatal bridge collapses. 00:02:49.400 --> 00:02:53.280 Now, we could massively scale down our use of sand, 00:02:53.280 --> 00:02:56.280 but we'd all still like to have buildings to live in, 00:02:56.280 --> 00:03:02.200 roads to travel on, and TVs to watch, and so the spice must flow. 00:03:02.200 --> 00:03:05.760 There are other options, though. We might be able to reduce the amount of sand we use 00:03:05.760 --> 00:03:08.840 by shifting to other sources of aggregate and silica 00:03:08.840 --> 00:03:12.400 like crushed rock, demolition material, and ore sand, 00:03:12.400 --> 00:03:16.680 a byproduct of the mining industry. Some have even suggested replacing sand 00:03:16.720 --> 00:03:21.680 with used, pyralized coffee grounds, which research has shown can even result 00:03:21.680 --> 00:03:25.040 in 30% stronger concrete in the right proportions. 00:03:25.040 --> 00:03:28.160 We also need to reuse what we've already extracted 00:03:28.160 --> 00:03:31.960 as much as we can. The bright side is that many processed forms of sand 00:03:31.960 --> 00:03:37.600 are basically infinitely recyclable. Around 80% of asphalt used in American roads 00:03:37.600 --> 00:03:42.680 is already recycled back into new asphalt, and glass can be broken down, tumbled, 00:03:42.680 --> 00:03:47.120 and turned back into sand. However, many forms of processed sand, 00:03:47.120 --> 00:03:51.920 such as rubber-like silicone polymers, can only be downcycled a limited number of times 00:03:51.920 --> 00:03:55.880 due to physical constraints, or they may be too contaminated to safely 00:03:55.880 --> 00:03:59.200 and economically recycle at scale with current technology. 00:03:59.200 --> 00:04:03.560 We also need to push for longer-lasting, repairable digital devices, 00:04:03.560 --> 00:04:07.880 because even the very cheap ones are made from materials that are ultimately limited. 00:04:08.960 --> 00:04:13.400 Life's a beach, and then you die. But first, you finish this video. 00:04:13.400 --> 00:04:17.800 Nice job. Hey, thanks for watching. Like the video if you liked it. Dislike it if you disliked it. 00:04:17.800 --> 00:04:22.400 Check out our other videos. We have many. And feel free to comment with video suggestions 00:04:22.400 --> 00:04:24.960 down in the description or in the comments. 00:04:26.480 --> 00:04:28.320 I need to go subscribe.