WEBVTT 00:01.533 --> 00:03.833 RONALD SMITH: Well, we're going to finish up the course by 00:03.833 --> 00:05.073 talking about energy. 00:06.067 --> 00:09.067 It's one of the primary--our need for energy is one of the 00:09.067 --> 00:14.967 primary ways that we interact with the environment, both 00:14.967 --> 00:18.427 draw resources from it, but also influence the 00:18.433 --> 00:19.073 environment. 00:19.067 --> 00:25.697 So I think it's a fitting way to end up the course. 00:25.700 --> 00:28.200 Today I'll probably just get through these two. 00:28.200 --> 00:30.800 Although, so I've put hydropower down here and 00:30.800 --> 00:32.970 renewable for the future. 00:32.967 --> 00:34.727 But it's a big player today. 00:34.733 --> 00:38.073 So I'll probably talk about hydropower today. 00:38.067 --> 00:44.097 But the rest will be discussed mostly on Wednesday. 00:44.100 --> 00:49.930 Now, over here, then, is the cartoon that will kind of 00:49.933 --> 00:52.303 remind us where everything fits in this 00:52.300 --> 00:57.870 picture of energy resources. 00:57.867 --> 01:03.397 Hydroelectric comes from rain falling on high ground, so it 01:03.400 --> 01:04.630 has potential energy. 01:04.633 --> 01:07.773 If it falls at sea level, you can't get any 01:07.767 --> 01:08.867 hydro energy from it. 01:08.867 --> 01:11.827 But if it falls at a high altitude, you've got that 01:11.833 --> 01:15.173 potential energy to draw from. 01:15.167 --> 01:19.227 The sun, through photosynthesis, will allow 01:19.233 --> 01:20.103 plants to grow. 01:20.100 --> 01:22.630 And then you can use that biomass in 01:22.633 --> 01:24.933 several different ways. 01:24.933 --> 01:31.073 Direct conversion of solar to, say, electricity. 01:31.067 --> 01:34.997 The differential heating from the sun, as you know, can 01:35.000 --> 01:36.930 create the winds. 01:36.933 --> 01:40.973 And the winds can turn a wind turbine. 01:40.967 --> 01:44.497 The winds also produce waves on the ocean. 01:44.500 --> 01:51.500 And those waves can be used to generate electricity. 01:51.500 --> 01:57.870 The heat from the sun also creates a temperature 01:57.867 --> 02:00.127 difference within the oceans. 02:00.133 --> 02:03.773 If the thermocline is there, you've got warm water above 02:03.767 --> 02:04.897 and cold water below. 02:04.900 --> 02:08.100 And that temperature difference can be used to 02:08.100 --> 02:11.500 derive a kind of renewable energy. 02:15.267 --> 02:19.127 The moon and the sun, their gravitational pull on the 02:19.133 --> 02:22.873 earth, produce tides. 02:22.867 --> 02:26.297 And that can be tapped for energy. 02:26.300 --> 02:29.070 Everything else comes from down within the 02:29.067 --> 02:31.797 interior of the earth. 02:31.800 --> 02:37.070 Oil and gas in the ocean bottom comes mostly from algae 02:37.067 --> 02:41.197 that grew, or phytoplankton that grew in the ocean 02:41.200 --> 02:43.900 millions of years ago and then fell to the bottom and got 02:43.900 --> 02:45.130 covered over. 02:47.500 --> 02:53.900 Coal, oil, and natural gas on the continents came from 02:53.900 --> 02:57.470 ancient biomass that got covered over. 03:00.267 --> 03:03.867 Geothermal comes from the fact that the interior of 03:03.867 --> 03:06.567 the earth is hot. 03:06.567 --> 03:10.397 And sometimes those hot rocks or hot lava can come up pretty 03:10.400 --> 03:12.130 close to the surface. 03:12.133 --> 03:15.533 And then that temperature gradient can be used for 03:15.533 --> 03:16.603 renewable energy. 03:16.600 --> 03:22.430 There is also uranium in the crust. In fact, some of this 03:22.433 --> 03:26.433 geothermal heat comes from the natural decay of uranium. 03:26.433 --> 03:29.603 But we can also dig up that uranium and use it in a 03:29.600 --> 03:33.530 nuclear power plant. 03:33.533 --> 03:34.973 What have I left out? 03:34.967 --> 03:37.827 Is there anything, any renewables you can think of 03:37.833 --> 03:40.533 that I don't have on there, or any form of energy not 03:40.533 --> 03:41.773 included there? 03:45.667 --> 03:47.597 OK, let's start to go through this then. 03:52.233 --> 03:56.403 So first of all, we have to remind ourselves about units. 03:56.400 --> 03:58.900 You guys are good at this by now, so I won't spend much 03:58.900 --> 03:59.500 time on it. 03:59.500 --> 04:06.400 But the SI system of unit of energy is the Joule. 04:06.400 --> 04:09.400 The unit of powers is the watt. 04:09.400 --> 04:17.030 Energy is power times the time over which you are using it. 04:17.033 --> 04:21.333 So a watt second is a Joule. 04:21.333 --> 04:25.903 And inversely, power is energy per unit time. 04:25.900 --> 04:29.130 So a Joule per second is a watt. 04:31.700 --> 04:35.100 However, when we're talking about electricity, there is a 04:35.100 --> 04:40.600 non-SI unit that is quite standard. 04:40.600 --> 04:42.400 And that's the kilowatt hour. 04:45.100 --> 04:47.500 So the watt is an SI system of unit. 04:47.500 --> 04:51.170 And we're used to putting a prefix on it 04:51.167 --> 04:52.367 kilo meeting 1,000. 04:52.367 --> 04:55.597 But then the time unit is an hour instead of a second. 04:55.600 --> 05:00.770 So that kind of messes up the SI system a little bit. 05:00.767 --> 05:04.667 But it's easy to go back and forth, because as you know, 05:04.667 --> 05:11.967 there are 3,600 seconds in an hour, 60 times 60. 05:11.967 --> 05:18.297 And therefore, one kilowatt hour is 3.6 megaJoules. 05:18.300 --> 05:20.700 And you don't have to memorize that. 05:20.700 --> 05:24.000 Just remember how many seconds there are in an hour. 05:24.000 --> 05:28.430 You can just work that out, that correspondence, anytime 05:28.433 --> 05:30.903 you need it. 05:30.900 --> 05:35.900 But it's odd, because it's an energy unit. 05:35.900 --> 05:40.370 It has a power times a time. 05:40.367 --> 05:43.097 So it's a little like this, except we end up not with 05:43.100 --> 05:46.270 Joules, but kilowatt hours. 05:46.267 --> 05:48.727 And if you're an economist and you want to have something to 05:48.733 --> 05:53.173 remember about this unit kilowatt hour, well, it's 05:53.167 --> 05:55.897 about $0.10 per kilowatt hour when I pay my 05:55.900 --> 05:58.930 electric bill at home. 05:58.933 --> 06:02.073 It varies by a factor of two or three across the country 06:02.067 --> 06:05.767 however, so that's not a fixed value. 06:05.767 --> 06:06.997 Any questions there? 06:09.567 --> 06:14.767 Now, it is convenient to break up our use of energy into 06:14.767 --> 06:18.497 three general categories. 06:18.500 --> 06:22.670 I think you'll appreciate this as we go through the material. 06:22.667 --> 06:25.097 Although it seems a little bit odd in the beginning to break 06:25.100 --> 06:26.870 it up in this particular way. 06:26.867 --> 06:29.697 We use energy for heating, heating your home, for 06:29.700 --> 06:32.830 example, just to raise the temperature. 06:32.833 --> 06:36.903 It's a very kind of low-tech way of using energy. 06:36.900 --> 06:41.170 In fact, it's the lowest form of energy when you're just 06:41.167 --> 06:44.097 using heat to raise the temperature of something. 06:44.100 --> 06:48.670 Transportation, moving goods or people. 06:48.667 --> 06:53.527 You can use gas in your car for that, or diesel fuel. 06:53.533 --> 07:00.373 And then electricity, which is a very broad category. 07:00.367 --> 07:06.467 It includes electric motors, lighting, electronics. 07:06.467 --> 07:09.397 But you can also use electronics for heating and 07:09.400 --> 07:11.400 for transportation. 07:11.400 --> 07:14.800 So electricity is a very broad category. 07:14.800 --> 07:18.330 But it's a much higher form of energy in a sense that I'll be 07:18.333 --> 07:24.173 describing later than just raising the temperature by 07:24.167 --> 07:26.497 adding heat. 07:26.500 --> 07:30.800 So we'll see how well that three-part categorization 07:30.800 --> 07:32.870 works for us as we go through. 07:32.867 --> 07:36.297 And then, of course, there's all these energy resources. 07:36.300 --> 07:39.570 These are the ones that I put on the cartoon over there. 07:39.567 --> 07:42.367 I'll just run over them briefly here and make a few 07:42.367 --> 07:44.267 additional comments. 07:44.267 --> 07:47.497 And we'll be going through most of these in some detail 07:47.500 --> 07:49.600 today and tomorrow. 07:49.600 --> 07:50.600 Coal. 07:50.600 --> 07:52.630 There's lots of it. 07:52.633 --> 07:56.603 It is rather heavily polluting, puts a lot of CO2 07:56.600 --> 07:59.530 in the atmosphere by burning coal, 07:59.533 --> 08:02.503 oxidizing it to form CO2. 08:02.500 --> 08:04.370 Oil and natural gas. 08:04.367 --> 08:07.367 There's less of it than coal. 08:07.367 --> 08:10.627 It's less polluting, both in terms of local air 08:10.633 --> 08:17.373 pollution--that is to say, less sulfur, less mercury, 08:17.367 --> 08:27.567 generally less ash also, it's at about 20% less CO2 08:27.567 --> 08:33.197 emissions per Joule of energy than is coal. 08:33.200 --> 08:39.600 So it's better in almost every respect than coal, except 08:39.600 --> 08:40.670 there's less of it. 08:40.667 --> 08:46.467 Nuclear plentiful, mostly non-polluting. 08:46.467 --> 08:49.597 Certainly, it puts no CO2 in the atmosphere. 08:49.600 --> 08:53.830 Waste storage is a problem, and public resistance because 08:53.833 --> 09:00.133 of a danger factor with nuclear plants. 09:00.133 --> 09:05.703 Hydroelectric falls into the renewable category. 09:05.700 --> 09:09.430 Clean, it's limited, and you lose natural rivers and 09:09.433 --> 09:15.033 ecosystems when you dam up large valley systems. There is 09:15.033 --> 09:19.003 a technology, though, called run-of-the-river 09:19.000 --> 09:22.030 hydroelectric, where you don't dam it. 09:22.033 --> 09:27.373 You just take the flow that's there on any particular day to 09:27.367 --> 09:29.127 put through your hydroelectric plant. 09:29.133 --> 09:32.673 That avoids the big dam, the big reservoir, and avoids a 09:32.667 --> 09:36.467 lot of the loss of natural rivers and ecosystems. So you 09:36.467 --> 09:41.267 can do hydroelectric without damming up. 09:41.267 --> 09:43.867 But it's not usually done. 09:43.867 --> 09:47.627 Wind is renewable, moderate cost. A lot of people don't 09:47.633 --> 09:51.373 like to look at windmills. 09:51.367 --> 09:53.367 So there's public resistance to it. 09:53.367 --> 09:56.367 Also, sometimes there can be noise and 09:56.367 --> 10:01.167 issues about bird kill. 10:01.167 --> 10:05.667 Solar renewable, high cost. Also, some people don't like 10:05.667 --> 10:10.567 to see the landscape covered with solar panels. 10:10.567 --> 10:13.197 Ocean waves and tides haven't made very much progress. 10:13.200 --> 10:13.830 It's renewable. 10:13.833 --> 10:17.603 It's very high cost to build something that's going to sit 10:17.600 --> 10:21.130 in the ocean and move around and draw energy from 10:21.133 --> 10:22.003 the waves and tides. 10:22.000 --> 10:24.700 The engineering really isn't there yet. 10:24.700 --> 10:26.330 And biomass. 10:26.333 --> 10:32.473 Renewable, polluting if you burn it, but no net CO2 10:32.467 --> 10:35.697 because you're drawing in CO2 from the atmosphere to make 10:35.700 --> 10:37.800 the biomass. 10:37.800 --> 10:40.400 And then when you burn it, you put the CO2 back. 10:40.400 --> 10:43.770 If you're only putting the CO2 back, it wouldn't be too bad. 10:43.767 --> 10:51.427 But you're also putting in ash, probably some mercury, 10:51.433 --> 10:56.673 other things along with that burning of the biomass. 10:56.667 --> 10:58.797 Any questions there? 10:58.800 --> 10:59.100 All right. 10:59.100 --> 11:00.970 So that's our starting point. 11:00.967 --> 11:03.327 Now, this diagram takes a bit of getting used to. 11:06.833 --> 11:07.873 It'll be in the, of course, in the lecture 11:07.867 --> 11:09.397 you'll have on the server. 11:09.400 --> 11:11.700 But I'll go through it. 11:11.700 --> 11:14.870 It's from the year 2006. 11:14.867 --> 11:18.697 And it's US per capita energy. 11:18.700 --> 11:21.630 And the units are in watts. 11:21.633 --> 11:24.973 So it's the rate at which we're using energy for a 11:24.967 --> 11:27.667 variety of different purposes. 11:27.667 --> 11:29.697 And I'll run through some of it, but I won't go through 11:29.700 --> 11:30.370 every detail. 11:30.367 --> 11:37.727 So here's oil, biomass, coal, natural gas. 11:37.733 --> 11:42.033 Obviously, oil, coal, and natural gas are the bigger 11:42.033 --> 11:43.903 inputs here. 11:43.900 --> 11:47.170 There's geothermal, wind, hydro, nuclear, and solar up 11:47.167 --> 11:49.397 at the top as well. 11:49.400 --> 11:52.430 Now, they've got a separate branch at the top for 11:52.433 --> 11:55.103 electricity production. 11:55.100 --> 11:58.200 Everything that's going to be used by first making 11:58.200 --> 12:03.930 electricity goes up to this top area here. 12:03.933 --> 12:08.503 And we see that a little bit of oil is used for that, but a 12:08.500 --> 12:09.770 lot of coal. 12:09.767 --> 12:13.767 In fact, almost all the coal that's used in this country is 12:13.767 --> 12:14.997 used for making electricity. 12:17.633 --> 12:22.973 A lot of natural gas, some geothermal, wind, hydro. 12:22.967 --> 12:26.127 All the hydro is used for electricity. 12:26.133 --> 12:28.833 All the nuclear is used for electricity. 12:28.833 --> 12:31.773 All the solar is used for electricity. 12:31.767 --> 12:40.297 Of the 4,400 watts per capita that's used for electricity 12:40.300 --> 12:48.830 production, 3,000 is lost as waste, energy waste, usually 12:48.833 --> 12:51.873 in the form of heat. 12:51.867 --> 12:57.327 And about 1,400 is used for residential, commercial, 12:57.333 --> 13:01.973 industrial, and even a tiny bit for transportation. 13:01.967 --> 13:03.867 So you see how the diagram works. 13:07.000 --> 13:08.830 And then over at the right-hand side, it has 13:08.833 --> 13:12.803 brought together all the waste from the different energy 13:12.800 --> 13:16.730 streams and put them up here, and then brought together all 13:16.733 --> 13:20.133 the useful energy and has categorized 13:20.133 --> 13:21.503 them here in the green. 13:21.500 --> 13:27.030 So you can read this by sources, by use, and by this 13:27.033 --> 13:34.003 last category of waste or useful work. 13:34.000 --> 13:35.670 Questions there? 13:35.667 --> 13:36.667 Yeah? 13:36.667 --> 13:40.567 STUDENT: Is the wasted energy wasted in the process of 13:40.567 --> 13:43.667 getting the energy, or is it wasted like when you leave a 13:43.667 --> 13:46.927 light on in a room, and you're not there? 13:46.933 --> 13:52.603 PROFESSOR: Mostly, I think this diagram is meant to 13:52.600 --> 13:54.930 include all of that. 13:54.933 --> 13:57.973 For example, it includes transmission loss. 13:57.967 --> 14:00.327 If you have a power plant where you're making 14:00.333 --> 14:02.973 electricity, and then you have to send it over power lines to 14:02.967 --> 14:04.667 get it to the consumer, there's going 14:04.667 --> 14:06.867 to be loss in that. 14:06.867 --> 14:09.827 And then there's going to be some--if you've got a motor 14:09.833 --> 14:13.003 running, but some of that energy goes into heat instead 14:13.000 --> 14:17.570 of turning the shaft of the motor, that would be lost. But 14:17.567 --> 14:20.897 I think it would also include your category, which is lost 14:20.900 --> 14:24.170 in the generation of the electricity. 14:24.167 --> 14:25.567 Yeah, good point. 14:29.300 --> 14:31.370 So we'll be going back to look at this 14:31.367 --> 14:34.267 dominance in fossil fuels. 14:34.267 --> 14:36.197 We can see it here. 14:36.200 --> 14:42.030 But we'll look at it again in other ways in just a moment. 14:42.033 --> 14:47.703 So electricity consumption per capita, remember this was USA. 14:51.900 --> 14:55.670 To put that in a somewhat broader context, let's look at 14:55.667 --> 14:59.167 that quantity for various countries. 14:59.167 --> 15:02.927 So this is per capita consumption 15:02.933 --> 15:05.833 of electrical energy. 15:05.833 --> 15:07.703 And United States is here. 15:07.700 --> 15:09.970 I've put the arrow there to show it. 15:09.967 --> 15:16.467 It's about 1,300 or 1,400 watts well, no, this is 15:16.467 --> 15:21.197 kilowatt hours, sorry kilowatt hours of energy 15:21.200 --> 15:24.700 used per year, yearly. 15:24.700 --> 15:28.430 And we are a high user. 15:28.433 --> 15:30.933 But there are higher users. 15:33.633 --> 15:36.573 Why would Iceland, Norway, Finland, and Canada 15:36.567 --> 15:38.927 use more than we? 15:38.933 --> 15:40.803 STUDENT: Heating? 15:40.800 --> 15:43.630 PROFESSOR: Sorry? 15:43.633 --> 15:44.603 STUDENT: Electric heating? 15:44.600 --> 15:46.470 PROFESSOR: Electric heat, yes. 15:46.467 --> 15:47.997 They do a lot of electrical heating. 15:48.000 --> 15:52.330 First of all, they've got a lot of electricity from hydro 15:52.333 --> 15:54.003 in those countries. 15:54.000 --> 15:58.600 So the electricity cost is pretty low. 15:58.600 --> 16:01.170 Generally, heating with electricity's kind of a waste 16:01.167 --> 16:03.067 of a high form of energy. 16:03.067 --> 16:07.567 But in those countries where you have a lot of electricity, 16:07.567 --> 16:08.967 you can heat your house with it. 16:08.967 --> 16:10.197 And they do. 16:10.200 --> 16:13.600 And that gives them a very high per capita use of 16:13.600 --> 16:14.230 electricity. 16:14.233 --> 16:16.473 Now, we heat our homes, too. 16:16.467 --> 16:21.097 But we do it more from natural gas, from oil. 16:21.100 --> 16:23.870 And so the heating we do would show up 16:23.867 --> 16:24.767 in a different category. 16:24.767 --> 16:29.927 It wouldn't show up in the electricity consumption. 16:29.933 --> 16:33.603 And compared to other countries, however, we are 16:33.600 --> 16:36.700 pretty high in our electricity use. 16:36.700 --> 16:39.570 Questions on that? 16:39.567 --> 16:41.867 And of course, these things have been growing over time. 16:41.867 --> 16:46.267 So we've got a green band, a red band, and a brown band 16:46.267 --> 16:52.297 renewables, nuclear, and fossil since 1980. 16:52.300 --> 16:57.300 And this is annual electricity generation worldwide. 16:57.300 --> 16:59.770 It's not per capita. 16:59.767 --> 17:01.167 So the unit is large. 17:01.167 --> 17:05.927 It's a terawatt hour per year. 17:05.933 --> 17:09.573 A terawatt hour per year. 17:09.567 --> 17:14.027 Remember, it goes kilo-, mega-, giga-, tera-, 17:14.033 --> 17:16.273 in powers of three. 17:16.267 --> 17:18.297 Terawatt hour. 17:18.300 --> 17:23.300 So nuclear has grown. 17:23.300 --> 17:30.170 But is steady the last 15, 20 years, renewable here is 17:30.167 --> 17:32.597 almost all hydro. 17:32.600 --> 17:35.700 Almost all the other renewables we'll be talking 17:35.700 --> 17:40.530 about in this course, at the moment, are pretty tiny. 17:40.533 --> 17:43.103 And so the only one that really shows up on a graph 17:43.100 --> 17:46.930 like this is hydroelectricity. 17:46.933 --> 17:51.733 And then the fossil fuel has been growing, unfortunately. 17:51.733 --> 17:55.833 And that's the big CO2 producer. 18:01.567 --> 18:05.527 So I'll stick--let's start with coal and see where that 18:05.533 --> 18:07.273 is and how we use it. 18:07.267 --> 18:09.267 There are the global coal deposits. 18:12.300 --> 18:14.500 I'll keep my comments to the northern hemisphere. 18:17.133 --> 18:19.433 China has quite a lot. 18:19.433 --> 18:23.473 Russia has the largest of any country. 18:23.467 --> 18:24.527 Europe has quite a bit. 18:24.533 --> 18:28.803 And the United States has quite a bit of coal. 18:28.800 --> 18:33.770 Zooming into the US, you see that there are coal beds along 18:33.767 --> 18:38.197 the Appalachian Mountains, some in the Midwest, and some 18:38.200 --> 18:42.900 in the Rocky Mountain West. They've sub-categorized it 18:42.900 --> 18:47.030 here in terms of different quality of coal. 18:47.033 --> 18:48.403 But I'm not going to go through that. 18:48.400 --> 18:50.230 I'm just going to show you generally 18:50.233 --> 18:52.403 where the coal is located. 18:52.400 --> 18:55.800 So if you want to generate energy and you live in this 18:55.800 --> 18:59.730 part of the world, you're probably going to find coal is 18:59.733 --> 19:01.033 the cheap way to do it. 19:03.767 --> 19:07.627 But maybe if you're over here, you'll find a different method 19:07.633 --> 19:12.103 because you're pretty far from the coal beds. 19:12.100 --> 19:13.170 How do you use coal? 19:13.167 --> 19:13.897 It's very simple. 19:13.900 --> 19:19.300 You burn it, you generate steam, you put the steam 19:19.300 --> 19:21.670 through a rotating turbine. 19:21.667 --> 19:24.867 The rotating turbine's hooked up to a generator. 19:24.867 --> 19:27.197 The generator makes electricity. 19:27.200 --> 19:31.170 You've got to cool that water off on the downside of the 19:31.167 --> 19:33.967 turbine, so it doesn't give back pressure. 19:33.967 --> 19:37.567 And putting gas back in the wrong direction, you've got to 19:37.567 --> 19:39.997 have cooling as well. 19:40.000 --> 19:40.970 Very simple idea. 19:40.967 --> 19:44.567 You just make steam and put it through a turbine. 19:44.567 --> 19:49.467 However, when you burn, of course, you're going to 19:49.467 --> 19:50.897 generated--you're oxidizing carbon. 19:50.900 --> 19:53.230 You're going to generate CO2. 19:53.233 --> 19:55.173 There's some sulfur in the coal. 19:55.167 --> 19:57.427 You're going to generate SO2. 19:57.433 --> 19:58.403 There's some mercury. 19:58.400 --> 20:03.070 You're going to generate HGO and NOX. 20:03.067 --> 20:03.927 Where does that come from? 20:03.933 --> 20:06.303 Well, remember, you're burning this coal in 20:06.300 --> 20:08.600 the presence of air. 20:08.600 --> 20:11.670 Air has N2 and O2. 20:11.667 --> 20:16.097 If your flame is hot enough, you'll dissociate N2 and 20:16.100 --> 20:21.270 dissociate O2, and they'll recombine NO. 20:21.267 --> 20:22.367 And then you've got a pollutant. 20:22.367 --> 20:26.567 So these are coming from the fuel. 20:26.567 --> 20:29.897 The carbon was in the fuel, the sulfur was in the fuel, 20:29.900 --> 20:31.200 the mercury was in the fuel. 20:31.200 --> 20:33.170 This is not coming from the fuel. 20:33.167 --> 20:36.727 This is coming from air that you're using 20:36.733 --> 20:39.833 to oxidize the coal. 20:39.833 --> 20:43.903 You're basically dissociating air and forming NOX. 20:43.900 --> 20:47.500 And then the particles are coming off the smoke. 20:47.500 --> 20:53.100 Remember that, because some other ways for generating heat 20:53.100 --> 20:56.170 will generate NOX even if there's no pollutant in the 20:56.167 --> 20:57.397 fuel itself. 20:59.533 --> 21:03.103 So when you see a power plant like this, those are the 21:03.100 --> 21:04.070 smokestacks. 21:04.067 --> 21:08.197 That's where the combustion products 21:08.200 --> 21:09.470 are going to be leaving. 21:09.467 --> 21:12.867 And that's the cooling tower, where you're cooling that 21:12.867 --> 21:16.867 steam on the backside of the turbine. 21:16.867 --> 21:18.897 So that is not smoke. 21:18.900 --> 21:21.930 That's just water vapor condensing to 21:21.933 --> 21:23.873 form a cloud there. 21:23.867 --> 21:27.067 And they have enough scrubbers on the stack that you're not 21:27.067 --> 21:28.997 seeing much of a smoke plume. 21:29.000 --> 21:33.130 But there is some coming off of the smokestacks there. 21:33.133 --> 21:36.403 So know what you're looking at when you see this. 21:36.400 --> 21:39.630 You know what you're looking at here. 21:39.633 --> 21:46.303 Long trains full with boxcars with coal transport the coal 21:46.300 --> 21:49.770 from the mines to the power plant. 21:49.767 --> 21:52.697 And you see the big piles of coal ready to be 21:52.700 --> 21:57.070 put into the burners. 21:57.067 --> 22:00.367 Now, there's this useful quantity called the emission 22:00.367 --> 22:04.767 coefficient, which is how much CO2 do you put in the 22:04.767 --> 22:09.897 atmosphere for every Joule of energy that you create 22:09.900 --> 22:12.370 electricity. 22:12.367 --> 22:20.097 And so the units here are CO2 emission coefficient in units 22:20.100 --> 22:23.870 of kilograms per gigaJoule. 22:23.867 --> 22:27.567 Kilograms of carbon dioxide per gigajoule of electrical 22:27.567 --> 22:29.627 energy produced. 22:29.633 --> 22:32.673 And different types of fuel is given here. 22:32.667 --> 22:35.527 The coals are generally in this region. 22:35.533 --> 22:44.133 And they are high, generally, about 95 kilograms of carbon 22:44.133 --> 22:48.273 dioxide for every gigaJoule that is produced. 22:48.267 --> 22:54.127 The oils, burning fuel oil, is about 20% lower. 22:54.133 --> 22:59.003 And some of the natural gases are even 20% lower than that. 22:59.000 --> 23:02.270 So they're still putting CO2 in the atmosphere, but at a 23:02.267 --> 23:06.967 rate that's maybe 30 or 40% less than coal does. 23:06.967 --> 23:12.097 So coal, in this measure, is the worst. And of course, in 23:12.100 --> 23:15.500 the local air pollution, it's also the worst of 23:15.500 --> 23:16.730 all of these options. 23:20.200 --> 23:22.470 And what is the future of coal? 23:22.467 --> 23:29.667 So here's a timeline, 1950 up to 2100, 90 years from now. 23:29.667 --> 23:34.697 The units are megatons of coal. 23:34.700 --> 23:37.470 And it's broken down by different parts of the 23:37.467 --> 23:43.667 economic world, North America, Europe, the Pacific countries, 23:43.667 --> 23:48.827 China, South Asian countries, and the former Soviet Union. 23:48.833 --> 23:50.633 Look at some of these characteristics. 23:50.633 --> 23:58.533 So North America has peaked and is going to be flat 23:58.533 --> 23:59.803 according to these projections. 24:02.267 --> 24:07.167 Europe peaked long ago and is now down to a fraction of what 24:07.167 --> 24:11.067 it was using 30 or 40 years ago. 24:11.067 --> 24:14.897 China is rapidly increasing at the moment. 24:14.900 --> 24:15.970 Of course, these are projections. 24:15.967 --> 24:17.527 We don't know exactly what they're going to do. 24:17.533 --> 24:25.373 But it looks like they're going to dominate coal use. 24:25.367 --> 24:26.797 They do already. 24:26.800 --> 24:28.900 It looks like they will continue to do that 24:28.900 --> 24:30.400 for 20 or 30 years. 24:30.400 --> 24:34.470 And then they'll probably run out of coal. 24:34.467 --> 24:36.767 The former Soviet Union, which remember that big blob up in 24:36.767 --> 24:38.597 the right-hand side of that earlier diagram? 24:42.800 --> 24:45.770 We're talking about that. 24:45.767 --> 24:49.497 And they're not using much of it yet. 24:49.500 --> 24:51.730 But that's probably all of this. 24:51.733 --> 24:56.773 So 50, 60 years from now, they will probably be the dominant 24:56.767 --> 24:59.827 user of coal. 24:59.833 --> 25:01.233 Any questions on that? 25:01.233 --> 25:01.733 Yeah? 25:01.733 --> 25:05.073 STUDENT: So the decrease over time for all of these regions, 25:05.067 --> 25:09.027 is that because of a change in energy use, or is it because 25:09.033 --> 25:10.503 they've run out of coal? 25:10.500 --> 25:12.330 PROFESSOR: I think it's mostly 25:12.333 --> 25:14.233 running out of coal. 25:14.233 --> 25:16.503 I don't think these projections that are put 25:16.500 --> 25:21.470 forward put much stock in the fact that we're going to 25:21.467 --> 25:23.667 purposely leave that stuff in the ground. 25:23.667 --> 25:24.927 Yeah. 25:29.933 --> 25:33.473 There's this term you hear on television all the time "clean 25:33.467 --> 25:35.727 coal." I can't tell you how many times I've seen this 25:35.733 --> 25:36.673 commercial. 25:36.667 --> 25:38.527 Maybe I listen to the wrong channels or something. 25:38.533 --> 25:41.403 But "clean coal" is a marketing term used to 25:41.400 --> 25:45.470 indicate coal burning without local air pollution. 25:45.467 --> 25:48.997 And to some extent, that is feasible today with the 25:49.000 --> 25:52.500 appropriate scrubbers on the smokestacks, but also with 25:52.500 --> 25:54.830 carbon capture and sequestration. 25:54.833 --> 26:00.503 The term "clean coal" usually infers both of these. 26:00.500 --> 26:05.000 But this second technology is not developed yet. 26:05.000 --> 26:07.670 So it's talking about something really 26:07.667 --> 26:10.197 far into the future. 26:10.200 --> 26:15.000 So there is no such thing as "clean coal" if, by that term, 26:15.000 --> 26:19.670 they mean both of these characteristics. 26:23.067 --> 26:25.227 So watch out for this term "clean coal." It's a little 26:25.233 --> 26:30.373 bit of a figment of the ad agency's imagination. 26:32.900 --> 26:36.070 So then we'll talk briefly about oil. 26:36.067 --> 26:36.927 Where is the oil? 26:36.933 --> 26:39.373 Well, I hope you can read that in the back. 26:39.367 --> 26:42.367 But most of it's in the Middle East Saudi Arabia, Kuwait, 26:42.367 --> 26:47.427 Iran, Iraq, and the Emirates. 26:47.433 --> 26:49.673 And so that's just what we know about from the 26:49.667 --> 26:50.497 newspapers, right? 26:50.500 --> 26:54.500 That's the cause of all of our headaches. 26:54.500 --> 26:57.400 The oil comes from the Middle East. But there is quite a bit 26:57.400 --> 27:00.770 in the USSR, Venezuela. 27:00.767 --> 27:04.827 The United States doesn't have much left. 27:04.833 --> 27:06.833 A few other countries have it. 27:06.833 --> 27:10.933 This is as of this moment. 27:10.933 --> 27:13.603 And what does it look like into the future? 27:13.600 --> 27:19.570 This goes to 2050 and starts in the year 1930. 27:19.567 --> 27:22.367 And it's in units--strange units, billions 27:22.367 --> 27:24.867 of barrels per year. 27:24.867 --> 27:35.127 GB/A, gigabarrels per annum, is the unit on that thing. 27:35.133 --> 27:40.873 And this brings us to this concept called "peak oil." The 27:40.867 --> 27:44.727 concept of peak oil is that oil use will, at some point, 27:44.733 --> 27:49.973 reach a maximum and then begin to decrease slowly. 27:49.967 --> 27:53.827 And it'll do that--it'll peak at different times in 27:53.833 --> 27:56.303 different countries for different reservoirs. 27:56.300 --> 28:01.700 For example, the US has probably passed its peak oil. 28:01.700 --> 28:08.630 It probably did it 10 or 20 years ago. 28:08.633 --> 28:11.503 Other countries, for example, the Middle East, won't reach 28:11.500 --> 28:14.230 their peak oil or maybe they're just about reaching it 28:14.233 --> 28:16.103 these are all projections, though, so 28:16.100 --> 28:17.100 they can't be trusted. 28:17.100 --> 28:22.430 But eventually, they will all taper off because you're using 28:22.433 --> 28:25.803 up the resource not because you've decided to keep it in 28:25.800 --> 28:28.400 the ground, but because you're using up the resource. 28:28.400 --> 28:33.270 So by the time we get to 2050, we'll be already halfway down 28:33.267 --> 28:33.827 from the peak. 28:33.833 --> 28:37.873 And of course, the price at that point will be climbing 28:37.867 --> 28:41.527 even much more steeply than we see today. 28:41.533 --> 28:44.303 Remember, the coal curves went further than that. 28:44.300 --> 28:50.800 That plot went out to 2100, of course, just in the former 28:50.800 --> 28:52.070 Soviet Union. 28:56.233 --> 29:00.703 You should know that New Haven is a big oil 29:00.700 --> 29:02.470 port for New England. 29:02.467 --> 29:05.867 Here's a Google picture of the port in New Haven. 29:05.867 --> 29:09.367 And all these white circles here, of course and there are 29:09.367 --> 29:13.227 dozens of them are oil tanks. 29:13.233 --> 29:15.903 So when you drive across the Q Bridge and look around, you'll 29:15.900 --> 29:17.970 see these things all over the place. 29:17.967 --> 29:21.867 And of course, that's because the oil tankers come in there, 29:21.867 --> 29:25.227 off-load their oil into these tanks, and then they are 29:25.233 --> 29:29.333 transported by truck to the rest of New England, used for 29:29.333 --> 29:30.773 a variety of purposes. 29:30.767 --> 29:36.267 Some of it's gasoline, some of it's crude oil. 29:36.267 --> 29:41.267 Among other uses is that it's used to drive the Harbor power 29:41.267 --> 29:47.897 plant, which is here, I guess, which gives us most of our 29:47.900 --> 29:51.270 electricity in New Haven. 29:51.267 --> 29:53.427 There's the power plant. 29:53.433 --> 29:57.203 It's called the Harbor Generating Station. 29:57.200 --> 30:03.300 Last year, it emitted almost 600,000 tons of CO2 into the 30:03.300 --> 30:08.630 atmosphere, while producing about 600,000 megawatt hours 30:08.633 --> 30:10.603 of electrical energy. 30:10.600 --> 30:14.100 Yale produces a little bit of its own. 30:14.100 --> 30:18.600 But this is the main generator plant for New Haven. 30:18.600 --> 30:22.200 This information and a lot more comes from a nice website 30:22.200 --> 30:27.830 called carma.org that tracks fossil fuel burning plants 30:27.833 --> 30:29.533 around the world. 30:29.533 --> 30:32.573 And you can get information on how much they burn, how much 30:32.567 --> 30:35.727 CO2 they put in the atmosphere, and so on, from 30:35.733 --> 30:37.173 that interesting website, carma.org. 30:41.900 --> 30:43.130 Questions here? 30:46.400 --> 30:51.930 Natural gas has suddenly become very important. 30:51.933 --> 30:56.903 These are the areas where we are currently getting natural 30:56.900 --> 31:02.000 gas or we'll soon be getting large amounts of natural gas. 31:02.000 --> 31:07.500 And they use this curious word "play" in the natural gas 31:07.500 --> 31:12.270 industry to indicate an area targeted for gas development. 31:12.267 --> 31:14.367 So if you run across that word, don't be confused. 31:14.367 --> 31:20.067 It has that particular term in that field of study. 31:20.067 --> 31:25.697 And it's a very exciting field right now, because they've 31:25.700 --> 31:27.070 learned how to get--suddenly they've learned how to get 31:27.067 --> 31:31.167 natural gas out of shale, using this 31:31.167 --> 31:32.397 method called fracting. 31:34.867 --> 31:37.467 So when you look at the timeline, this is similar to 31:37.467 --> 31:45.597 the ones I've shown you for coal and oil, except it's for 31:45.600 --> 31:48.970 natural gas and just for the US. 31:48.967 --> 31:54.327 And the timeline is a shorter one, 1990 to 2035. 31:54.333 --> 31:58.303 They've got these various categories tight gas, onshore 31:58.300 --> 32:01.730 conventional, offshore, coal bed methane. 32:01.733 --> 32:04.073 But look at this new one, shale gas. 32:04.067 --> 32:05.127 It was almost nothing. 32:05.133 --> 32:08.533 And then just a couple years ago, they discovered this 32:08.533 --> 32:12.173 method for getting natural gas out of shales. 32:12.167 --> 32:14.967 And suddenly, that's become the biggest one. 32:14.967 --> 32:16.567 And it's growing. 32:16.567 --> 32:19.297 So this is a big surprise. 32:19.300 --> 32:23.470 It humbles us in terms of our ability to predict the future 32:23.467 --> 32:26.327 of energy resources, because we didn't see this one coming. 32:26.333 --> 32:30.003 And temporarily, this is going to really shake the markets 32:30.000 --> 32:34.730 and is shaking the markets, and is, to some extent, 32:34.733 --> 32:39.873 slowing down the development of renewables, because now 32:39.867 --> 32:45.297 we've got a cheap new source of natural gas, which, as they 32:45.300 --> 32:48.330 say, is cleaner than coal. 32:48.333 --> 32:53.403 However, it's still a fossil fuel, still putting CO2 in the 32:53.400 --> 32:55.000 atmosphere. 32:55.000 --> 32:56.270 Questions on this? 32:59.633 --> 33:03.003 OK, we'll move on to nuclear. 33:03.000 --> 33:05.300 That's what a typical nuclear plant looks like. 33:05.300 --> 33:06.470 These are cooling towers. 33:06.467 --> 33:09.727 You don't see any smokestacks. 33:09.733 --> 33:11.103 You're not burning anything. 33:15.267 --> 33:17.697 You've got the reactor core. 33:17.700 --> 33:19.830 You produce steam from that. 33:19.833 --> 33:21.733 And the rest you know. 33:21.733 --> 33:24.533 Once you get the steam, you put it through a turbine, 33:24.533 --> 33:27.303 turbine runs a generator to make electricity. 33:27.300 --> 33:31.830 You've got to cool down the back side with cooling water. 33:31.833 --> 33:33.673 That's what the cooling tower is for. 33:33.667 --> 33:35.097 And then you can recycle the water. 33:38.800 --> 33:44.870 Now, remember, this is nuclear fission. 33:44.867 --> 33:50.397 This is taking large nuclei and splitting them apart to 33:50.400 --> 33:52.070 get energy. 33:52.067 --> 33:56.567 This is a book you'd find, in an introductory textbook in 33:56.567 --> 33:57.967 nuclear physics. 33:57.967 --> 34:01.967 It's the binding energy per nucleon as the function of the 34:01.967 --> 34:05.427 mass number of the element that you're talking about. 34:08.500 --> 34:13.600 It has a peak roughly where iron sits, and decreases to 34:13.600 --> 34:17.000 the right and the left of that. 34:17.000 --> 34:22.130 This means that if you split apart heavy nuclei, you can 34:22.133 --> 34:27.233 get energy out, or if you combine like nuclei, you get 34:27.233 --> 34:29.473 energy out. 34:29.467 --> 34:31.927 That's called fusion. 34:31.933 --> 34:37.973 This is the way the sun makes its energy, by taking hydrogen 34:37.967 --> 34:41.827 and hydrogen and making helium. 34:41.833 --> 34:44.633 And this is the way we make energy in a conventional 34:44.633 --> 34:47.903 nuclear plant, by taking uranium 235 and splitting it 34:47.900 --> 34:52.770 apart into lighter nuclei and getting energy out that way. 34:56.067 --> 35:00.797 We're still working on a way to do this synthetically. 35:00.800 --> 35:03.900 That's one of the great unsolved problems in nuclear 35:03.900 --> 35:08.070 physics, is how to make a fusion reactor that'll 35:08.067 --> 35:10.227 generate electricity for us. 35:10.233 --> 35:12.933 We've been trying for 50 years, still haven't 35:12.933 --> 35:13.673 been able to do it. 35:13.667 --> 35:17.297 So all the nuclear plants we're talking about here use 35:17.300 --> 35:21.030 fission to generate electricity. 35:21.033 --> 35:22.303 Questions on that? 35:25.567 --> 35:30.797 These are the countries that do it, ranked by the percent 35:30.800 --> 35:33.900 of their total electricity generation 35:33.900 --> 35:36.600 that is done by nuclear. 35:36.600 --> 35:40.930 Lithuania and France lead the way with 75%. 35:40.933 --> 35:47.333 The United States is over here with 22% percent, and so on. 35:47.333 --> 35:50.133 So we are not a leader in this by any means. 35:50.133 --> 35:51.403 But we do some. 35:54.167 --> 35:56.427 And here's where the uranium is located. 35:56.433 --> 36:00.533 The big purple box for each country just gives you a 36:00.533 --> 36:05.173 measure of how much uranium is believed to be stored in the 36:05.167 --> 36:09.167 earth's crust within the national borders of each of 36:09.167 --> 36:10.167 these countries. 36:10.167 --> 36:11.667 So we have a lot. 36:11.667 --> 36:13.797 Canada has a lot. 36:13.800 --> 36:14.930 Kazakhstan has a lot. 36:14.933 --> 36:16.073 Russia has some. 36:16.067 --> 36:17.427 Australia has a whole lot. 36:20.233 --> 36:21.433 What about Connecticut? 36:21.433 --> 36:23.433 Yes, we get some of ours from Connecticut. 36:23.433 --> 36:27.503 There's a nuclear plant in the southeast corner of the state 36:27.500 --> 36:30.270 called Millstone 2 and Millstone 3. 36:30.267 --> 36:34.997 That's what it looks like from the air. 36:35.000 --> 36:41.370 And it generates about 2,000 megawatts of energy. 36:47.267 --> 36:52.027 But it has a sad history in a way. 36:52.033 --> 36:56.303 The install capacity, in terms of gigawatts, is given here. 36:56.300 --> 37:01.500 And the number of reactors is given here, 100, 200, 300. 37:01.500 --> 37:05.330 And you see that it grew rapidly during the '70s. 37:05.333 --> 37:09.333 But then because of these two famous incidents Three Mile 37:09.333 --> 37:15.233 Island in eastern Pennsylvania and Chernobyl in the Ukraine 37:15.233 --> 37:17.673 suddenly, people got spooked about the 37:17.667 --> 37:19.467 use of nuclear plants. 37:19.467 --> 37:24.297 And really, nothing much has been built for the last 20 37:24.300 --> 37:29.730 years, even 25 years, in terms of new power plants. 37:29.733 --> 37:32.273 So that is a large build-out. 37:32.267 --> 37:35.697 But it's pretty much flat for the last couple of decades. 37:40.267 --> 37:42.167 And what to do with the nuclear waste? 37:42.167 --> 37:46.127 So I mentioned that there was a plant--there's a nuclear 37:46.133 --> 37:49.203 plant in southeast Connecticut. 37:49.200 --> 37:51.700 There used to be one up on the river, up on the Connecticut 37:51.700 --> 37:53.100 River, in the center part of the state. 37:53.100 --> 37:55.230 That's called the Connecticut Yankee Plant. 37:55.233 --> 37:58.173 That was shut down about 15 years ago. 37:58.167 --> 38:01.867 And not only did they have nowhere to ship the waste, the 38:01.867 --> 38:05.867 nuclear waste when that plant was active, but when they 38:05.867 --> 38:08.297 stopped the plant and decommissioned it, they still 38:08.300 --> 38:09.570 had no place to put the waste. 38:09.567 --> 38:12.027 So it's still sitting there. 38:12.033 --> 38:15.333 15 years after the plant was shut down, you still have all 38:15.333 --> 38:19.203 the nuclear waste below ground in these big tubes, because we 38:19.200 --> 38:21.830 don't know yet in this country how to get 38:21.833 --> 38:23.673 rid of nuclear waste. 38:23.667 --> 38:24.927 So that's a real problem. 38:27.733 --> 38:29.703 Questions on that? 38:32.400 --> 38:36.300 I think we can get through hydro then. 38:36.300 --> 38:39.700 The basic idea is a simple one. 38:39.700 --> 38:42.470 For hydroelectric power, as I said before, you need to get 38:42.467 --> 38:46.227 the water falling on high terrain. 38:46.233 --> 38:50.003 Now, that's likely to happen anyway, because when the air 38:50.000 --> 38:55.400 comes along and lifts up over a mountain, you cool the air 38:55.400 --> 38:58.800 adiabatically, generate clouds and precipitation. 38:58.800 --> 39:01.170 So you've got this process called orographic 39:01.167 --> 39:03.197 precipitation, mountain-induced 39:03.200 --> 39:07.400 precipitation, that automatically gives you a lot 39:07.400 --> 39:09.870 of rain on high terrain. 39:09.867 --> 39:11.427 So it's kind of perfect in a way. 39:14.100 --> 39:18.930 The potential energy, then, you've produced is the product 39:18.933 --> 39:21.803 this is right out of your physics textbook potential 39:21.800 --> 39:27.370 energy is the product of mass, gravity, and height. 39:27.367 --> 39:28.627 It's simply Mgh. 39:31.467 --> 39:34.967 And that would have units of, well, Joules. 39:37.967 --> 39:40.427 Now, your job is not done. 39:40.433 --> 39:43.803 You've got to get this into your hydroelectric plant, get 39:43.800 --> 39:47.870 it through a turbine, and make electricity from it. 39:47.867 --> 39:52.097 But at least the energy is there from the rain falling on 39:52.100 --> 39:52.930 high ground. 39:52.933 --> 39:55.573 And as I mentioned before, it can be either a dammed up 39:55.567 --> 39:58.997 lake, or there are these new run-of-the-river designs, 39:59.000 --> 40:01.730 where you don't have to dam, you just take the water. 40:01.733 --> 40:04.333 But then you're subject to whatever the river flow 40:04.333 --> 40:06.973 happens to be at the moment. 40:06.967 --> 40:09.527 You don't have any way to store and use 40:09.533 --> 40:13.573 it during dry periods. 40:13.567 --> 40:16.167 So there's a typical dam system. 40:16.167 --> 40:21.297 This is from Hydro-Quebec up in northern Quebec. 40:21.300 --> 40:25.630 A large dammed lake goes down through a power plant, 40:25.633 --> 40:29.803 generates electricity, off you go. 40:29.800 --> 40:31.130 Here are some examples. 40:31.133 --> 40:34.233 I'll show you some of these in just a minute. 40:34.233 --> 40:38.503 The James Bay Project, up in northern Quebec, generates 40:38.500 --> 40:44.730 16,000 megawatts when it's operating at full capacity. 40:44.733 --> 40:49.733 The famous Grand Coulee Dam, about 7,000 megawatts. 40:49.733 --> 40:52.773 These are all the most famous dams in this country. 40:52.767 --> 40:54.367 Hoover Dam's 2,000. 40:54.367 --> 40:56.067 Glen Canyon's 1,300. 40:56.067 --> 40:58.397 And the Three Gorges dam, the new one that opened up in 40:58.400 --> 41:01.900 China about 10 years ago, is the largest of all. 41:01.900 --> 41:04.370 That's about 20,000 megawatts. 41:04.367 --> 41:06.997 Let's take a look at these. 41:07.000 --> 41:10.500 So the James Bay Project is here. 41:10.500 --> 41:11.300 Do you know where you are? 41:11.300 --> 41:13.070 So here's Labrador. 41:13.067 --> 41:16.427 Connecticut's down here somewhere. 41:16.433 --> 41:20.573 And Hudson Bay is here, and James Bay is there. 41:20.567 --> 41:24.097 So they dammed up some of these rivers on their way into 41:24.100 --> 41:26.300 James Bay and Hudson Bay. 41:30.333 --> 41:34.133 A word about the seasonality of hydroelectric. 41:34.133 --> 41:38.103 And I'll use Hydro-Quebec as an example in my discussion of 41:38.100 --> 41:39.730 seasonality. 41:39.733 --> 41:44.203 As you know from this course, rainfall normally comes 41:44.200 --> 41:47.170 heavier in some seasons of the year than in other 41:47.167 --> 41:48.027 seasons of the year. 41:48.033 --> 41:54.903 Well, in Canada, for reasons we've already touched on, the 41:54.900 --> 42:00.830 maximum demand is in winter because of electrical heating. 42:00.833 --> 42:03.303 And yet, in winter, most of the 42:03.300 --> 42:06.670 precipitation falls as snow. 42:06.667 --> 42:09.297 So it doesn't go right into the rivers. 42:09.300 --> 42:12.670 So the maximum natural river flow is in the spring and 42:12.667 --> 42:16.867 early summer from snow melt. 42:16.867 --> 42:18.627 So how do you solve that problem? 42:18.633 --> 42:20.473 Your demand is in winter. 42:20.467 --> 42:23.667 Your natural river flow is in spring and early summer. 42:23.667 --> 42:26.427 Well, there are two ways to solve it. 42:26.433 --> 42:28.073 One is the obvious way. 42:28.067 --> 42:32.767 The reservoirs can store that water for six months 42:32.767 --> 42:35.227 until you need it. 42:35.233 --> 42:38.773 And the other thing is to sell it to a place that has a 42:38.767 --> 42:39.897 different demand curve. 42:39.900 --> 42:44.330 In other words, they sell a lot of energy to us down here 42:44.333 --> 42:48.933 in New England, because a lot of our maximum demand is in 42:48.933 --> 42:51.533 summer for air conditioning. 42:51.533 --> 42:55.573 So using those two methods, they solve this 42:55.567 --> 43:00.797 incompatibility between their demand and their 43:00.800 --> 43:01.900 natural river flow. 43:01.900 --> 43:05.470 So as you go around the world, not only for hydro, but for 43:05.467 --> 43:08.797 the other renewables, you want to look at this issue. 43:08.800 --> 43:10.500 When is the demand? 43:10.500 --> 43:12.930 When is the source available? 43:12.933 --> 43:14.973 And find out some way to solve that problem. 43:14.967 --> 43:18.567 That applies to almost every renewable energy source. 43:18.567 --> 43:22.127 The timing isn't what you would want. 43:22.133 --> 43:23.373 Questions on that? 43:26.800 --> 43:30.600 Another famous one is the Columbia River and the Snake 43:30.600 --> 43:33.230 River that feeds into it. 43:33.233 --> 43:36.003 So here is Washington and Oregon. 43:39.967 --> 43:41.627 The biggest--there are a lot of big dams along there. 43:41.633 --> 43:47.103 I think the biggest is a Grand Coulee Dam, which is there. 43:47.100 --> 43:52.600 And that's the one I gave you the production numbers for. 43:52.600 --> 43:54.230 Another big area in this country is the 43:54.233 --> 43:57.173 Colorado River system. 43:57.167 --> 44:01.327 And the two most famous parts there are the Glen Canyon Dam 44:01.333 --> 44:05.473 with Lake Powell backed up behind it and Hoover Dam with 44:05.467 --> 44:09.267 Lake Mead backed up behind it. 44:09.267 --> 44:15.067 But on the scale of things, those are relatively small. 44:15.067 --> 44:17.927 Those are those numbers there. 44:17.933 --> 44:21.073 I mean, they look majestic to see them. 44:21.067 --> 44:24.597 But they're not as large a some of the other big, new 44:24.600 --> 44:26.670 hydroelectric plants we have around the world. 44:30.833 --> 44:34.533 And then the Three Gorges Dam in China, you see it here, 44:34.533 --> 44:36.233 backed up a huge lake. 44:36.233 --> 44:41.973 And that has that huge number of 20,000 megawatts of energy 44:41.967 --> 44:44.567 at full capacity. 44:44.567 --> 44:45.527 How does it work? 44:45.533 --> 44:49.373 Well, you've got your reservoir with a certain 44:49.367 --> 44:51.297 height of water. 44:51.300 --> 44:53.800 Hydrostatically, that generates high pressure at the 44:53.800 --> 44:58.200 bottom, which pushes water down through this smooth tube 44:58.200 --> 45:04.970 called the penstock, smooth to avoid turbulence and losses. 45:04.967 --> 45:07.467 And then it goes right into the turbine. 45:07.467 --> 45:09.127 And then the rest of the story you know. 45:09.133 --> 45:11.633 You turn the turbine, the turbine turns a generator, 45:11.633 --> 45:13.273 which makes electricity. 45:13.267 --> 45:14.267 And off you go. 45:14.267 --> 45:18.027 And the water then goes on down the river. 45:23.200 --> 45:25.800 There's the Grand Coulee Dam. 45:25.800 --> 45:27.930 And I want to show you this. 45:27.933 --> 45:31.433 There's a couple of people standing there for scale. 45:31.433 --> 45:34.973 There is the turbine, one of the turbines for the Grand 45:34.967 --> 45:35.597 Coulee Dam. 45:35.600 --> 45:40.300 These are really massive turbines that generate a lot 45:40.300 --> 45:41.530 of electricity. 45:46.300 --> 45:49.830 Yeah, so let me just wrap up with this then. 45:49.833 --> 45:53.873 I pulled off this data from the DOE a few years ago, 45:53.867 --> 45:58.327 comparing three states Connecticut, Ohio, and Oregon. 45:58.333 --> 46:04.203 Now, Connecticut, as we've seen, has some petroleum and 46:04.200 --> 46:06.470 gas being used to generate electricity. 46:06.467 --> 46:08.327 But it also has a big nuclear component. 46:08.333 --> 46:10.433 In fact, that's the largest single component. 46:10.433 --> 46:12.733 44% of our electricity in 46:12.733 --> 46:14.833 Connecticut comes from nuclear. 46:14.833 --> 46:19.633 And our CO2 emissions, on average, are pretty low 46:19.633 --> 46:22.603 because of that. 46:22.600 --> 46:26.700 Ohio doesn't have too much coal of its own. 46:26.700 --> 46:30.670 But West Virginia lies just east of it. 46:30.667 --> 46:33.597 It shares a long border with West Virginia, which is a 46:33.600 --> 46:36.670 strong coal-producing state. 46:36.667 --> 46:39.167 And so they ship the coal over the border, burn it. 46:39.167 --> 46:44.527 And 86, 87% of the electricity in Ohio is 46:44.533 --> 46:45.973 generated by coal burning. 46:49.233 --> 46:51.733 Oregon, on the other hand, being on the West Coast, 46:51.733 --> 46:58.203 mountainous, heavy rainfall, 81% is hydroelectric. 46:58.200 --> 47:03.230 So here, within the same country, within the US of A, 47:03.233 --> 47:05.733 because of the way these states are located in 47:05.733 --> 47:10.603 different provinces, you've got three completely different 47:10.600 --> 47:16.270 dominant electrical energy sources hydroelectric, coal, 47:16.267 --> 47:18.597 and nuclear. 47:18.600 --> 47:20.270 So there is a lot of variability out there. 47:20.267 --> 47:25.827 And it depends on what's available nearby, basically. 47:25.833 --> 47:27.103 Any questions on this? 47:30.900 --> 47:31.900 That was a lot. 47:31.900 --> 47:33.300 Let's finish it for today. 47:33.300 --> 47:36.430 And on Wednesday, we'll do the renewables.