1 00:00:00,500 --> 00:00:01,968 [SQUEAKING] 2 00:00:01,968 --> 00:00:04,428 [RUSTLING] 3 00:00:04,428 --> 00:00:05,412 [CLICKING] 4 00:00:15,698 --> 00:00:17,990 PROFESSOR: And then, so the reason why all this matters 5 00:00:17,990 --> 00:00:20,090 is heat is a big deal. 6 00:00:20,090 --> 00:00:23,060 90 percent-- and you can study this. 7 00:00:23,060 --> 00:00:24,680 These are wonderful charts to study. 8 00:00:24,680 --> 00:00:27,470 But depending on what you want to do, 9 00:00:27,470 --> 00:00:30,020 heat is almost always involved, heat being 10 00:00:30,020 --> 00:00:33,020 a transfer of thermal energy. 11 00:00:33,020 --> 00:00:35,690 And so 90 percent of the current energy budget 12 00:00:35,690 --> 00:00:39,350 basically goes through the middle in some way. 13 00:00:39,350 --> 00:00:41,360 That's a lot. 14 00:00:41,360 --> 00:00:44,170 But then if you look at things like this-- 15 00:00:44,170 --> 00:00:46,170 which you shouldn't, because you can't read it-- 16 00:00:46,170 --> 00:00:47,040 but if you blow up-- 17 00:00:47,040 --> 00:00:49,370 these are all the inputs on the left, 18 00:00:49,370 --> 00:00:51,260 all the ways we make energy. 19 00:00:51,260 --> 00:00:52,490 Here's how we use it. 20 00:00:52,490 --> 00:00:54,180 And here's the result. 21 00:00:54,180 --> 00:00:57,860 Here's where I want to get the punch line, is rejected energy. 22 00:00:57,860 --> 00:01:01,580 Whatever these units, doesn't matter, it's 60 percent. 23 00:01:01,580 --> 00:01:03,040 What does rejected energy mean? 24 00:01:03,040 --> 00:01:04,360 Wasted. 25 00:01:04,360 --> 00:01:06,580 All this precious fossil fuel, stuff we're burning, 26 00:01:06,580 --> 00:01:08,330 and all the solar energy we're collecting, 27 00:01:08,330 --> 00:01:09,580 anything we're doing here-- 28 00:01:09,580 --> 00:01:14,010 60 percent of it goes into heat, wasted heat. 29 00:01:14,010 --> 00:01:16,030 And so the reason why this matters 30 00:01:16,030 --> 00:01:17,860 is because there are these materials 31 00:01:17,860 --> 00:01:20,870 that we can use to try to capture some of that. 32 00:01:20,870 --> 00:01:21,500 All right? 33 00:01:21,500 --> 00:01:23,580 There are materials we can use to try to capture some of that, 34 00:01:23,580 --> 00:01:25,038 and it all comes down to chemistry. 35 00:01:25,038 --> 00:01:27,910 These are called phase change materials. 36 00:01:27,910 --> 00:01:31,760 And if you plot the melting temperature-- that's this. 37 00:01:31,760 --> 00:01:33,500 That's this melting temperature, right? 38 00:01:33,500 --> 00:01:38,700 Tm-- versus how much of its delta H, how much delta 39 00:01:38,700 --> 00:01:42,090 H you have, you get all sorts of classes and materials. 40 00:01:42,090 --> 00:01:44,760 But, you know, so you might want a certain melting temperature 41 00:01:44,760 --> 00:01:47,010 from wherever you're operating, but then you might not 42 00:01:47,010 --> 00:01:49,142 get a high enough delta H. Or you 43 00:01:49,142 --> 00:01:51,600 might want really high delta Hs, but then the thing doesn't 44 00:01:51,600 --> 00:01:54,340 melt until 700 C, which is way too high. 45 00:01:54,340 --> 00:01:56,222 So we've got to fill this out. 46 00:01:56,222 --> 00:01:57,180 We need materials here. 47 00:01:57,180 --> 00:01:58,138 We need materials here. 48 00:01:58,138 --> 00:02:00,400 That's a call to chemistry. 49 00:02:00,400 --> 00:02:02,550 That's a call to chemistry. 50 00:02:02,550 --> 00:02:04,990 And it all has to do with the phase change. 51 00:02:04,990 --> 00:02:05,800 It's a weird name. 52 00:02:05,800 --> 00:02:08,229 These are called phase change materials, 53 00:02:08,229 --> 00:02:11,020 but that's true of all materials. 54 00:02:11,020 --> 00:02:14,140 But here, when you're talking about storing thermal energy, 55 00:02:14,140 --> 00:02:17,160 we use the term phase change materials.