1 00:00:00,012 --> 00:00:06,641 Hello, we're going to dive a little deeper into the second law of energy 2 00:00:06,641 --> 00:00:12,322 conversion today. we are covering the energy conversion 3 00:00:12,322 --> 00:00:19,537 section where we're dealing with energy converting from one form to another. 4 00:00:19,537 --> 00:00:25,845 And the laws of nature that we have to abide by in order to make that 5 00:00:25,845 --> 00:00:29,539 conversion. And the, whereas the first law talks 6 00:00:29,539 --> 00:00:32,813 about energy in has got to equal energy out. 7 00:00:32,813 --> 00:00:38,446 We can't create or destroy total energy. This one has to do with the value of 8 00:00:38,446 --> 00:00:43,416 energy if you recall, that when I just summarized it very quickly. 9 00:00:43,416 --> 00:00:48,708 That is like even though you have a pound of gold and a pound of lead, they have 10 00:00:48,708 --> 00:00:52,561 different values. Well, if you have one kilojoule of work, 11 00:00:52,561 --> 00:00:57,472 and one kilojoule of thermal energy, they have the same energy but they have 12 00:00:57,472 --> 00:01:02,167 different values in most cases. value from a thermonamic value, and 13 00:01:02,167 --> 00:01:07,112 interestingly enough, the thermonamic value ties with economic value. 14 00:01:07,112 --> 00:01:14,178 work and electricity will cost, if you're trying to buy it, will cost you a lot 15 00:01:14,178 --> 00:01:19,109 more than natural gas, for instance, to produce heat. 16 00:01:19,109 --> 00:01:25,635 So when we say value, it's not just thermodynamic but also economic value, 17 00:01:25,635 --> 00:01:32,554 Many things have what we call a quality that we arbitrarily assign to them of 18 00:01:32,554 --> 00:01:39,720 one, which is the highest quality. Work, electricity, kinetic energy and 19 00:01:39,720 --> 00:01:47,072 radiation all have a quality value of 1 and then we downgrade anything that has 20 00:01:47,072 --> 00:01:51,884 quality value less than these to some lower number than one. 21 00:01:51,884 --> 00:01:56,796 and work of course we, we produce it with a power plant. 22 00:01:56,796 --> 00:02:03,281 Electricity we produce it with a generator, kinetic energy, wind turbine. 23 00:02:03,281 --> 00:02:09,722 I hadn't talked about this one. wind turbine of course, takes the kinetic 24 00:02:09,722 --> 00:02:14,651 energy out of the air. Or extract some of it, not all of it. 25 00:02:14,651 --> 00:02:21,145 And extracts the kinetic energy from the wind and uses that kinetic energy to 26 00:02:21,145 --> 00:02:27,568 rotate a shaft to turn a generator to produce electricity, which a wind farm 27 00:02:27,568 --> 00:02:31,633 does. Radiation we produce, use that radiation 28 00:02:31,633 --> 00:02:36,972 energy from the sun to produce electricity with a solar cell. 29 00:02:36,972 --> 00:02:43,319 and then we have thermal energy. That one, thermal energy is the oddball 30 00:02:43,319 --> 00:02:49,804 here as unfortunately are just a fact that most of our energy comes from fossil 31 00:02:49,804 --> 00:02:55,732 fuels which we burn the fossil fuels to produce thermal energy or heat. 32 00:02:55,732 --> 00:03:00,859 In order to get the energy out of. So most of the energy conversion 33 00:03:00,859 --> 00:03:07,080 processes that it, somewhere along the line involves thermal energy that we've 34 00:03:07,080 --> 00:03:13,238 extracted or heat or we've extracted from burning fossil fuels, and that value 35 00:03:13,238 --> 00:03:19,905 vary, of that energy, that thermal energy or heat, varies with the temperature Of 36 00:03:19,905 --> 00:03:24,444 the object that, has that heat or thermal energy. 37 00:03:24,444 --> 00:03:31,733 And, of course, combustion is what produces the high temperature that has, 38 00:03:31,733 --> 00:03:39,699 that has the high thermal energy. now, unless this is a rather complicated 39 00:03:39,699 --> 00:03:47,292 slide, but let me, let me just walk through it with you here and number one, 40 00:03:47,292 --> 00:03:54,557 the thing we want to notice is the vertical scale of high up has higher 41 00:03:54,557 --> 00:03:59,296 quality and low down. On the bottom, has 0 qualities. 42 00:03:59,296 --> 00:04:03,829 So we go from 0 quality energy to high quality energy of 1. 43 00:04:03,829 --> 00:04:10,484 And, you know, if you've got 3000 degrees fahrenheit, you're somewhere right here. 44 00:04:10,484 --> 00:04:14,675 The lower the temperature, the lower the quality is. 45 00:04:14,675 --> 00:04:20,693 So Quality and temperature go together. Here's temperature on the shown scale on 46 00:04:20,693 --> 00:04:26,696 this side and the quality value on that side, but high temperature increases the 47 00:04:26,696 --> 00:04:32,472 quality of the thermal energry. and work and electricity of course are up 48 00:04:32,472 --> 00:04:35,882 here, they're up there with a quality of one. 49 00:04:35,882 --> 00:04:42,767 That's the work and electricity which is the most valuable in things we have to 50 00:04:42,767 --> 00:04:49,822 pay the most for when we want them. The the lower temperature examples of the 51 00:04:49,822 --> 00:04:55,517 lower temperature thermal energy. That we want and use, is cooking. 52 00:04:55,517 --> 00:05:01,242 Cooking doesn't have to be at five, 3000 degrees Fahrenheit obviously. 53 00:05:01,242 --> 00:05:06,362 We burn everything. But cooking is not so high temperature. 54 00:05:06,362 --> 00:05:12,056 Hot water for our showers is only around 30, 40 degrees Centigrade. 55 00:05:12,056 --> 00:05:18,630 And 100, 110 degrees Fahrenheit. space heating is very low, relatively 56 00:05:18,630 --> 00:05:22,873 speaking. So you're talking about a house that's 57 00:05:22,873 --> 00:05:28,317 maintained at 22 degrees Centigrade or 72 degrees Fahrenheit. 58 00:05:28,317 --> 00:05:35,867 And, when the outside temperature is, maybe, 0 degrees centigrade or 32 degrees 59 00:05:35,867 --> 00:05:42,012 Fahrenheit, so that that is low quality energy, which is good if that's what we 60 00:05:42,012 --> 00:05:45,382 need because it's cheaper and easier to get. 61 00:05:45,382 --> 00:05:51,085 The lower the quality is of the energy or the thermal energy in this case The 62 00:05:51,085 --> 00:05:56,669 cheaper it is, and the easier it is to get and convert and produce. 63 00:05:56,669 --> 00:06:01,289 and at ambient temperature, we have zero quality. 64 00:06:01,289 --> 00:06:04,899 Now, here's 1 thing we have to understand. 65 00:06:04,899 --> 00:06:08,712 There's a lot of energy in the ambient. Air. 66 00:06:08,712 --> 00:06:15,237 The molecules in the air are bouncing around and that will with thermal energy 67 00:06:15,237 --> 00:06:20,097 at ambient temperature. So there's a lot of energy there. 68 00:06:20,097 --> 00:06:24,272 A lot of energy. But it has no value, has no value. 69 00:06:24,272 --> 00:06:31,710 I'll give you a quick story I, a, [UNKNOWN], sheet rock we call it here in 70 00:06:31,710 --> 00:06:36,400 the U.S. Sheet rock manufacturers came to me one 71 00:06:36,400 --> 00:06:43,954 time and wanted to help him, or take a project to deal wall boards that makes up 72 00:06:43,954 --> 00:06:50,520 the inside wall of houses. And put something in the wall boards that 73 00:06:50,520 --> 00:06:53,887 would. Take the energy out of the ambient air, 74 00:06:53,887 --> 00:06:56,677 and produce electricity to drive the house. 75 00:06:56,677 --> 00:06:59,517 And he was convinced this was the grate idea. 76 00:06:59,517 --> 00:07:04,237 As a matter of fact when I told him I couldn't do that and it violated all the 77 00:07:04,237 --> 00:07:07,757 laws of nature. He actually went to the president of the 78 00:07:07,757 --> 00:07:13,597 university and he had to be the vice president of marketing and tried to force 79 00:07:13,597 --> 00:07:18,321 me to, to take it. But you can't, can't violate the laws of 80 00:07:18,321 --> 00:07:22,602 nature. so there's a lot of energy in the ambient 81 00:07:22,602 --> 00:07:25,679 temperature air. But it has no value. 82 00:07:25,679 --> 00:07:29,701 Has zero value. Zero quality over here at ambient 83 00:07:29,701 --> 00:07:34,304 temperature. They go together, even though there's a 84 00:07:34,304 --> 00:07:41,027 lot of thermal energy there, there's not anything you can do with it, nothing you 85 00:07:41,027 --> 00:07:45,350 can do with it. So, you can study this in a little bit 86 00:07:45,350 --> 00:07:52,461 and again, high temperature, high quality up here, low temperature Zero quality and 87 00:07:52,461 --> 00:07:55,796 decreasing value. you have .1, .2, .3, .5. 88 00:07:55,796 --> 00:08:01,603 You go on up the scale and energy value as you move on up to a higher and higher 89 00:08:01,603 --> 00:08:05,698 temperature. combustion flames have pretty high 90 00:08:05,698 --> 00:08:11,712 temperature and have pretty high quality of the thermal energy in that flame. 91 00:08:11,712 --> 00:08:18,142 Let me. Okay, so here's, here's what the second 92 00:08:18,142 --> 00:08:23,752 law of thermodynamics tells you, you cannot do. 93 00:08:23,752 --> 00:08:29,462 There's a big X here, tells you, you cannot do it. 94 00:08:29,462 --> 00:08:34,886 I cannot, no one can. Cannot take low, quality in here. 95 00:08:34,886 --> 00:08:41,191 Again, this is high quality. It's vertical in the highest part of the 96 00:08:41,191 --> 00:08:47,300 scale and, and low quality is the bottom part of the scale of the graph. 97 00:08:47,300 --> 00:08:53,150 I put heat in at a low temperature. You could even say, well I'm going to put 98 00:08:53,150 --> 00:08:57,882 it in an ambient temperature. And I'm going to convert it 100% on a one 99 00:08:57,882 --> 00:09:02,690 on one basis to electricity of work. Does not violate the first law of 100 00:09:02,690 --> 00:09:06,334 thermodynamics. I put in one unit of energy here and I 101 00:09:06,334 --> 00:09:10,889 get out one unit of energy there. So I have not created or destroyed 102 00:09:10,889 --> 00:09:14,306 energy. But the second law of thermodynamics will 103 00:09:14,306 --> 00:09:18,282 not let you do that. Why won't it let you do that? Why does 104 00:09:18,282 --> 00:09:23,032 gravity pull down? I don't know. We just observe the laws of nature and 105 00:09:23,032 --> 00:09:27,307 don't try to figure out why the universe was made the way it was. 106 00:09:27,307 --> 00:09:32,957 but this is, the, one of the reasons the 2nd law is so misunderstood, is it's one 107 00:09:32,957 --> 00:09:37,872 of the very few laws, as a matter of fact as far as I know, the only one. 108 00:09:37,872 --> 00:09:41,261 And that is totally stated as a negative statement. 109 00:09:41,261 --> 00:09:46,114 You notice that the first law is energy in has got to equal energy out, because 110 00:09:46,114 --> 00:09:51,284 you cannot or destroy it, total energy. But this one merely says what we cannot 111 00:09:51,284 --> 00:09:54,066 do. Well, when we stop and think about it, 112 00:09:54,066 --> 00:09:58,582 there are an infinite number of ways to make a negative statement. 113 00:09:58,582 --> 00:10:02,926 I'll give you one of the, the most obscure ways that you hear connected to 114 00:10:02,926 --> 00:10:06,175 the 2nd law alot. And that is, the [INAUDIBLE] of the 115 00:10:06,175 --> 00:10:10,748 universe cannot decrease. Well, that, that's a true statement, but, 116 00:10:10,748 --> 00:10:15,636 it doesn't give me many, much intuity of understanding what the 2nd law says you 117 00:10:15,636 --> 00:10:19,182 can or cannot do. But you hear many, many, many different 118 00:10:19,182 --> 00:10:22,032 statements of the law, all of them negative. 119 00:10:22,032 --> 00:10:28,232 And onto the equivalent you can prove any accurately stated negative statement of 120 00:10:28,232 --> 00:10:33,125 the second law from any other. Any negative statement of the second law 121 00:10:33,125 --> 00:10:36,942 could accurately state it can be proven from any other. 122 00:10:36,942 --> 00:10:42,168 And so that's one reason that intuitively it's a little bit harder to graph. 123 00:10:42,168 --> 00:10:47,700 And it's certainly is not intuitive that you can't do this, let me give you a very 124 00:10:47,700 --> 00:10:51,912 fundamental example. If I have a hot cup of coffee, if I have 125 00:10:51,912 --> 00:10:56,343 a cup of coffee and it's at room temperature, I bring it into the 126 00:10:56,343 --> 00:11:01,242 classroom and I set it down, and it's cooled down to where it's ambient 127 00:11:01,242 --> 00:11:06,765 temperature, 70 degrees farheinheit or 21 degrees centigrate, and and I say I want 128 00:11:06,765 --> 00:11:11,093 a hot cup of coffee. Well, there's nothing that says that some 129 00:11:11,093 --> 00:11:16,065 process won't Cool the ambient air down a little bit and put that thermal energy 130 00:11:16,065 --> 00:11:18,844 into the cup and make the cup hot, hot coffee. 131 00:11:18,844 --> 00:11:23,691 That would be increase in the quality of the thermal energy in the coffee, but it 132 00:11:23,691 --> 00:11:27,341 won't, can't happen. You've never observed that to happen, 133 00:11:27,341 --> 00:11:31,242 it'll always cool down. We can go from high quality energy to low 134 00:11:31,242 --> 00:11:35,637 quality energy very easily and as a matter of fact, the universe moves in 135 00:11:35,637 --> 00:11:39,527 that direction. but we cannot go from low quality energy 136 00:11:39,527 --> 00:11:43,202 and up to high quality energy with no other net effect. 137 00:11:43,202 --> 00:11:47,752 With no other net effect. And notice, there's nothing else going on 138 00:11:47,752 --> 00:11:50,752 here. 1 unit of energy, low-quality thermal 139 00:11:50,752 --> 00:11:56,542 energy coming in, and I have high quality electricity at work, 1 unit coming out. 140 00:11:56,542 --> 00:12:02,700 Nothing else going on, it cannot happen. That's 1 statement of the 2nd Law of 141 00:12:02,700 --> 00:12:07,145 Thermodynamics. What can we do? Well, let me get rid of 142 00:12:07,145 --> 00:12:12,120 this, my writing here. What can we do? Well this is what a auto 143 00:12:12,120 --> 00:12:18,399 engine, an auto engine, a diesel A deisel engine or a, or a electric power plant, 144 00:12:18,399 --> 00:12:22,708 does, this power system represents any, any one of those. 145 00:12:22,708 --> 00:12:27,947 And what does it do? Well we put in combustion energy into the plant, we 146 00:12:27,947 --> 00:12:33,850 drive it with, and drive the engine with gasoline that comes from oil or we drive 147 00:12:33,850 --> 00:12:39,412 the deisel with deisel fuel or drive a power plant with natural gas or coal. 148 00:12:39,412 --> 00:12:45,635 And we put it in, we put 3 BTU's in. Notice it's not 0 quality though, it's 149 00:12:45,635 --> 00:12:51,952 not 0 quality, it has some quality because it's, it's at a relatively high 150 00:12:51,952 --> 00:12:56,567 temperature. We can produce high quality energy, but 151 00:12:56,567 --> 00:13:00,874 to do it we've got to degrade Other energy, some of it. 152 00:13:00,874 --> 00:13:04,483 We cannot do it. We cannot have 3 BTUs going in, and 3 153 00:13:04,483 --> 00:13:09,426 BTUs coming out as electricity. We can have 1 BTU of en-, of electricity 154 00:13:09,426 --> 00:13:14,806 coming out, and 2 BTUs coming out at ambient temperature that we are rejecting 155 00:13:14,806 --> 00:13:19,592 to the river, with a quality of zero. So if you're going to upgrade. 156 00:13:19,592 --> 00:13:24,567 From part of the energy, I've got to downgrade the rest of it. 157 00:13:24,567 --> 00:13:29,592 I cannot upgrade all of it. So I can only upgrade it if I use the 158 00:13:29,592 --> 00:13:35,813 downgrading of, of, of some section, some segment of the energy to drive the 159 00:13:35,813 --> 00:13:39,755 upgrade. And that's what an auto engine, a diesel 160 00:13:39,755 --> 00:13:45,942 power, diesel engine or power plant does. And this is maybe a little difficult to 161 00:13:45,942 --> 00:13:51,441 grasp, but is 1 thing, by the way I've had people and read articles where 162 00:13:51,441 --> 00:13:57,725 engineers are really stupid because we're throwing away 2/3's of our energy to the 163 00:13:57,725 --> 00:13:59,952 river. We need to be using. 164 00:13:59,952 --> 00:14:05,159 Well, that would be great if you could do it, but the second law of thermodynamics 165 00:14:05,159 --> 00:14:10,124 will not allow you to convert all of this combustion energy into electricity. 166 00:14:10,124 --> 00:14:15,097 You have got to throw a lot of it away at zero quality, or a low quality close to 167 00:14:15,097 --> 00:14:17,594 zero. If you're throwing it away to the 168 00:14:17,594 --> 00:14:20,494 atmosphere of the river. It is a 0 quality. 169 00:14:20,494 --> 00:14:25,450 So there's, a, people say we're throwing away all this thermal energy at ambient 170 00:14:25,450 --> 00:14:29,404 temperature, and we need to recover it and do something with it. 171 00:14:29,404 --> 00:14:34,342 It has no value just like the ambient am, molecules in the air have lots of energy 172 00:14:34,342 --> 00:14:37,201 as they bounce around, but they have no value. 173 00:14:37,201 --> 00:14:41,087 We can't do anything with them. That's just the laws of nature. 174 00:14:41,087 --> 00:14:45,509 Okay. that's a very quick overview of the 175 00:14:45,509 --> 00:14:52,877 second law of energy conversion. Which is highly misunderstood, or not 176 00:14:52,877 --> 00:14:59,754 understood at all by a lot of, lot of people and a lot of our Population. 177 00:14:59,754 --> 00:15:03,898 Which is not surprising. when we look at it, we see that it's not 178 00:15:03,898 --> 00:15:07,795 very straightforward. To understand, particularly from an 179 00:15:07,795 --> 00:15:11,457 intuitive concept. Why you have to do it the way we have, 180 00:15:11,457 --> 00:15:14,518 nature says we have to do it is not clear at all. 181 00:15:14,518 --> 00:15:19,119 But why does gravity pull down when i jump out of a building, I fall down 182 00:15:19,119 --> 00:15:23,069 rather than going up. That's just how the laws of nature are. 183 00:15:23,069 --> 00:15:24,093 Okay, thank you.