WEBVTT 00:00:00.000 --> 00:00:02.440 align:middle line:90% [SQUEAKING] 00:00:02.440 --> 00:00:04.392 align:middle line:90% [RUSTLING] 00:00:04.392 --> 00:00:05.368 align:middle line:90% [CLICKING] 00:00:05.368 --> 00:00:10.740 align:middle line:90% 00:00:10.740 --> 00:00:13.740 align:middle line:84% DAVID HSU: Hi, everyone, and welcome back to the MIT 00:00:13.740 --> 00:00:15.970 align:middle line:90% class on urban energy systems. 00:00:15.970 --> 00:00:19.180 align:middle line:84% Wherever you're seeing this lecture, please subscribe. 00:00:19.180 --> 00:00:21.180 align:middle line:84% You can either find it on the web page 00:00:21.180 --> 00:00:25.660 align:middle line:84% where you found this video or ask the instructor. 00:00:25.660 --> 00:00:29.620 align:middle line:84% So let's get back to the topic for today, 00:00:29.620 --> 00:00:32.850 align:middle line:84% which is going to be cities and decarbonization. 00:00:32.850 --> 00:00:35.070 align:middle line:90% What is the role of cities? 00:00:35.070 --> 00:00:38.010 align:middle line:84% Again, I'm David Hsu, and if you're 00:00:38.010 --> 00:00:41.340 align:middle line:84% thinking about how cities can take action 00:00:41.340 --> 00:00:43.350 align:middle line:84% or what their role is in decarbonization, 00:00:43.350 --> 00:00:47.100 align:middle line:84% you have found the right place and your people. 00:00:47.100 --> 00:00:49.770 align:middle line:84% So I want to cover just briefly how you're going 00:00:49.770 --> 00:00:51.150 align:middle line:90% to prepare for class this week. 00:00:51.150 --> 00:00:52.420 align:middle line:90% This is our second class. 00:00:52.420 --> 00:00:55.170 align:middle line:84% I want to make sure that everyone's caught up. 00:00:55.170 --> 00:00:57.690 align:middle line:84% First, the introductory reading from last week 00:00:57.690 --> 00:00:59.620 align:middle line:90% is fairly short and scalable. 00:00:59.620 --> 00:01:02.650 align:middle line:84% So it's easy to catch up, but you should catch up. 00:01:02.650 --> 00:01:07.110 align:middle line:84% And it's particularly important to look at MacKay chapter 2. 00:01:07.110 --> 00:01:10.072 align:middle line:90% Again, it's MacKay chapter 2. 00:01:10.072 --> 00:01:13.200 align:middle line:84% There's the initial problem set due Monday night. 00:01:13.200 --> 00:01:15.480 align:middle line:84% You can just access the problem set 00:01:15.480 --> 00:01:20.065 align:middle line:84% by going directly to this Google form, the link on the screen. 00:01:20.065 --> 00:01:21.690 align:middle line:84% You should do the reading for this week 00:01:21.690 --> 00:01:22.830 align:middle line:90% that's on the syllabus. 00:01:22.830 --> 00:01:26.340 align:middle line:84% I also show the reading for this week on the next page. 00:01:26.340 --> 00:01:29.310 align:middle line:84% And then you should watch the rest of this video lecture. 00:01:29.310 --> 00:01:32.267 align:middle line:84% And during the reading and while watching the video lecture, 00:01:32.267 --> 00:01:34.350 align:middle line:84% it's important for you to write down the questions 00:01:34.350 --> 00:01:35.793 align:middle line:90% that you have for discussion. 00:01:35.793 --> 00:01:37.710 align:middle line:84% And then I want you to feel free to share them 00:01:37.710 --> 00:01:41.220 align:middle line:84% on Slack, whenever, asynchronously, or in our class 00:01:41.220 --> 00:01:44.270 align:middle line:90% meeting on Tuesday. 00:01:44.270 --> 00:01:45.710 align:middle line:90% So the material for today-- 00:01:45.710 --> 00:01:46.880 align:middle line:90% again, I won't go over them. 00:01:46.880 --> 00:01:48.140 align:middle line:90% These are all in your syllabus. 00:01:48.140 --> 00:01:49.682 align:middle line:84% But these will also be in the slides, 00:01:49.682 --> 00:01:51.160 align:middle line:90% so you can follow the links. 00:01:51.160 --> 00:01:55.876 align:middle line:84% The first four readings are the required readings, 00:01:55.876 --> 00:01:59.650 align:middle line:84% a kind of gathering of very different readings. 00:01:59.650 --> 00:02:02.050 align:middle line:84% And the last two readings are optional readings 00:02:02.050 --> 00:02:07.700 align:middle line:84% that give additional information to the articles above. 00:02:07.700 --> 00:02:10.419 align:middle line:84% So what I want to start with is MacKay chapter 2, 00:02:10.419 --> 00:02:12.635 align:middle line:84% what he calls the balance sheet, and it's 00:02:12.635 --> 00:02:14.890 align:middle line:84% an important set of concepts simply 00:02:14.890 --> 00:02:17.500 align:middle line:84% so we can think about the energy system. 00:02:17.500 --> 00:02:20.860 align:middle line:84% And very simply, what MacKay is trying to do in his book 00:02:20.860 --> 00:02:24.370 align:middle line:84% is contrast these red and green bars. 00:02:24.370 --> 00:02:27.430 align:middle line:84% Energy consumption is on the left and red, 00:02:27.430 --> 00:02:30.140 align:middle line:84% and energy production is on the right in green. 00:02:30.140 --> 00:02:32.560 align:middle line:84% And so when MacKay titles his book 00:02:32.560 --> 00:02:34.930 align:middle line:84% Sustainable Energy-- without the hot air, what 00:02:34.930 --> 00:02:37.690 align:middle line:84% we're trying to do is replace our current level 00:02:37.690 --> 00:02:40.943 align:middle line:84% of consumption with entirely renewable resources, 00:02:40.943 --> 00:02:43.360 align:middle line:84% and that's how we're going to achieve a sustainable energy 00:02:43.360 --> 00:02:44.480 align:middle line:90% system. 00:02:44.480 --> 00:02:47.500 align:middle line:84% And so a sustainable energy system 00:02:47.500 --> 00:02:50.260 align:middle line:84% would be if our total conceivable sustainable 00:02:50.260 --> 00:02:52.270 align:middle line:84% production sources, on the right, 00:02:52.270 --> 00:02:54.790 align:middle line:84% are greater than our total consumption. 00:02:54.790 --> 00:02:56.860 align:middle line:84% And an unsustainable energy system 00:02:56.860 --> 00:02:59.470 align:middle line:84% would be where our total consumption of energy 00:02:59.470 --> 00:03:01.990 align:middle line:84% is larger than our total conceivable sustainable 00:03:01.990 --> 00:03:02.780 align:middle line:90% production. 00:03:02.780 --> 00:03:05.050 align:middle line:84% And, of course, these two bars will change over 00:03:05.050 --> 00:03:09.100 align:middle line:84% time as our expectations around consumption change 00:03:09.100 --> 00:03:12.640 align:middle line:84% and our technologies and our institutions 00:03:12.640 --> 00:03:14.890 align:middle line:84% and our markets for sustainable production change. 00:03:14.890 --> 00:03:16.180 align:middle line:90% But that's the challenge. 00:03:16.180 --> 00:03:18.850 align:middle line:84% The challenge is to try to put these two in balance 00:03:18.850 --> 00:03:21.550 align:middle line:84% and at least have total sustainable production that 00:03:21.550 --> 00:03:24.790 align:middle line:84% is enough to meet all of our societal needs, 00:03:24.790 --> 00:03:28.720 align:middle line:84% or our global societal needs, for energy consumption. 00:03:28.720 --> 00:03:32.620 align:middle line:84% And so what that might look like is the key forms of consumption 00:03:32.620 --> 00:03:35.020 align:middle line:90% on the left-hand stack in red-- 00:03:35.020 --> 00:03:38.110 align:middle line:84% that is the energy we need for transportation, including 00:03:38.110 --> 00:03:40.360 align:middle line:90% cars, planes, and freight. 00:03:40.360 --> 00:03:42.310 align:middle line:84% It's the energy we need to heat and cool 00:03:42.310 --> 00:03:43.840 align:middle line:90% the spaces that we live in. 00:03:43.840 --> 00:03:46.420 align:middle line:84% That can wildly differ across countries. 00:03:46.420 --> 00:03:50.140 align:middle line:84% It's a basic need for lighting so we can see at night. 00:03:50.140 --> 00:03:53.530 align:middle line:84% It's a growing need for energy for information systems 00:03:53.530 --> 00:03:56.170 align:middle line:90% and our other gadgets. 00:03:56.170 --> 00:03:58.000 align:middle line:90% The fifth point, food-- 00:03:58.000 --> 00:03:59.830 align:middle line:84% a tremendous amount of energy goes 00:03:59.830 --> 00:04:05.530 align:middle line:84% into growing and transporting and keeping our food cold. 00:04:05.530 --> 00:04:07.570 align:middle line:84% And, finally, the manufacturing-- 00:04:07.570 --> 00:04:10.060 align:middle line:84% for all the technologies or all the gadgets 00:04:10.060 --> 00:04:13.150 align:middle line:84% we need to do transportation or heating and cooling, 00:04:13.150 --> 00:04:14.830 align:middle line:84% like information systems and food, 00:04:14.830 --> 00:04:17.154 align:middle line:84% we have to make these things in the first place, 00:04:17.154 --> 00:04:20.079 align:middle line:84% and that requires a tremendous amount of energy. 00:04:20.079 --> 00:04:23.230 align:middle line:84% On the right-hand side, our sustainable production stack 00:04:23.230 --> 00:04:24.860 align:middle line:90% has a number of categories. 00:04:24.860 --> 00:04:27.760 align:middle line:84% The good thing is-- and I'll try to emphasize this in the class 00:04:27.760 --> 00:04:32.080 align:middle line:84% repeatedly-- is that we have many sustainable technologies 00:04:32.080 --> 00:04:33.950 align:middle line:90% that can produce energy. 00:04:33.950 --> 00:04:36.160 align:middle line:90% We have wind and solar. 00:04:36.160 --> 00:04:38.230 align:middle line:84% Solar energy can be harnessed in the form 00:04:38.230 --> 00:04:42.430 align:middle line:84% of photovoltaic or solar cells that produce electricity. 00:04:42.430 --> 00:04:45.685 align:middle line:84% We can harness solar energy through thermal energy, 00:04:45.685 --> 00:04:48.880 align:middle line:84% and we can also harness solar energy through biomass, 00:04:48.880 --> 00:04:51.460 align:middle line:84% by harvesting the potential of the Earth 00:04:51.460 --> 00:04:53.980 align:middle line:84% to engage in photosynthesis, create crops 00:04:53.980 --> 00:04:56.510 align:middle line:84% that we then can use for other things, 00:04:56.510 --> 00:04:59.890 align:middle line:90% including burning in engines. 00:04:59.890 --> 00:05:03.910 align:middle line:84% Hydroelectric power is producing electricity directly from-- 00:05:03.910 --> 00:05:08.050 align:middle line:84% or mechanical storage directly from-- hydropower. 00:05:08.050 --> 00:05:11.590 align:middle line:84% Wave energy and tide energy are two sources of energy 00:05:11.590 --> 00:05:16.000 align:middle line:84% that come from the Earth on a regular basis. 00:05:16.000 --> 00:05:18.910 align:middle line:84% Geothermal energy also comes from the Earth. 00:05:18.910 --> 00:05:22.060 align:middle line:84% The heat inside the Earth can be harnessed to produce energy. 00:05:22.060 --> 00:05:25.768 align:middle line:84% And finally, nuclear, And MacKay puts it with a question mark 00:05:25.768 --> 00:05:27.310 align:middle line:84% because it's not clear whether or not 00:05:27.310 --> 00:05:30.250 align:middle line:84% nuclear energy or nuclear power counts as sustainable. 00:05:30.250 --> 00:05:34.240 align:middle line:84% It is low carbon, but as I said in an earlier class, 00:05:34.240 --> 00:05:37.030 align:middle line:84% we have questions about how do we handle 00:05:37.030 --> 00:05:40.040 align:middle line:84% the fuel for nuclear power plants, 00:05:40.040 --> 00:05:42.250 align:middle line:84% how do we handle the waste from nuclear power plants, 00:05:42.250 --> 00:05:43.900 align:middle line:84% and whether or not that will be fully 00:05:43.900 --> 00:05:46.960 align:middle line:90% sustainable in the long run. 00:05:46.960 --> 00:05:49.560 align:middle line:84% And so I want to cover two physical concepts from MacKay 00:05:49.560 --> 00:05:51.870 align:middle line:84% chapter 2 that I think are basically 00:05:51.870 --> 00:05:54.660 align:middle line:84% going to be the most important physical concepts you 00:05:54.660 --> 00:05:56.940 align:middle line:90% need to understand this class. 00:05:56.940 --> 00:05:59.790 align:middle line:84% And the first one, quite simply, is energy. 00:05:59.790 --> 00:06:03.760 align:middle line:84% It's the quantitative property of doing work. 00:06:03.760 --> 00:06:06.730 align:middle line:84% Energy can be neither destroyed nor created, 00:06:06.730 --> 00:06:10.480 align:middle line:84% one of our fundamental laws of thermodynamics. 00:06:10.480 --> 00:06:15.220 align:middle line:84% Energy can be transformed into light, heat, or mass, hence 00:06:15.220 --> 00:06:19.870 align:middle line:84% the famous equation by Einstein, E equals mc squared, 00:06:19.870 --> 00:06:23.500 align:middle line:84% energy equals mass times of speed of light squared. 00:06:23.500 --> 00:06:27.110 align:middle line:84% This is a fundamental finding out of relativity. 00:06:27.110 --> 00:06:30.180 align:middle line:84% And, of course, energy can take many different forms. 00:06:30.180 --> 00:06:33.080 align:middle line:84% And we use it in many different forms in our energy system. 00:06:33.080 --> 00:06:34.760 align:middle line:90% Energy can be kinetic. 00:06:34.760 --> 00:06:36.440 align:middle line:90% It can be chemical. 00:06:36.440 --> 00:06:38.090 align:middle line:90% We can have potential energy. 00:06:38.090 --> 00:06:39.830 align:middle line:84% We have mechanical energy, let's say, 00:06:39.830 --> 00:06:42.320 align:middle line:84% stored in the elastic properties of materials 00:06:42.320 --> 00:06:45.530 align:middle line:84% and, of course, biological energy, which is fundamentally 00:06:45.530 --> 00:06:47.990 align:middle line:84% chemical energy, but we have different modes 00:06:47.990 --> 00:06:50.870 align:middle line:84% of perhaps using that chemical energy in our muscles, 00:06:50.870 --> 00:06:53.830 align:middle line:90% in animals, in ecosystems. 00:06:53.830 --> 00:06:55.580 align:middle line:84% And we're going to measure energy in terms 00:06:55.580 --> 00:06:57.560 align:middle line:90% of units of kilowatt-hours. 00:06:57.560 --> 00:07:01.220 align:middle line:84% You'll see energy referred to in terms of British Thermal Units, 00:07:01.220 --> 00:07:05.090 align:middle line:84% BTUs, something only used in the US and America 00:07:05.090 --> 00:07:06.410 align:middle line:90% or the United States. 00:07:06.410 --> 00:07:10.400 align:middle line:84% Therms, joules, calories, are all units for energy. 00:07:10.400 --> 00:07:13.220 align:middle line:84% They can all be converted to kilowatt-hours. 00:07:13.220 --> 00:07:16.010 align:middle line:84% A specific category I just want to highlight below 00:07:16.010 --> 00:07:20.270 align:middle line:84% is fossil fuels are sometimes measured in barrels of oil, 00:07:20.270 --> 00:07:23.480 align:middle line:84% short tons of coal, cubic feet of natural gas. 00:07:23.480 --> 00:07:24.980 align:middle line:84% That's because that's how we measure 00:07:24.980 --> 00:07:27.260 align:middle line:84% the things we trade in commodity markets 00:07:27.260 --> 00:07:29.420 align:middle line:90% for commoditized fossil fuels. 00:07:29.420 --> 00:07:32.480 align:middle line:84% But, again, the amount of energy in a barrel of oil 00:07:32.480 --> 00:07:35.960 align:middle line:84% and a short ton of coal and cubic foot of natural gas 00:07:35.960 --> 00:07:39.040 align:middle line:84% can be converted to kilowatt-hours. 00:07:39.040 --> 00:07:41.790 align:middle line:84% So just to give you a few examples, example 1, 00:07:41.790 --> 00:07:44.040 align:middle line:84% you may have had the frustrating experience 00:07:44.040 --> 00:07:47.190 align:middle line:84% of having gone to the gym, foolishly 00:07:47.190 --> 00:07:49.890 align:middle line:84% counting your calories, realizing you worked out 00:07:49.890 --> 00:07:51.740 align:middle line:84% for an hour on a running treadmill, 00:07:51.740 --> 00:07:54.540 align:middle line:84% and it's only equivalent to three Oreos. 00:07:54.540 --> 00:07:56.520 align:middle line:90% You can also look at example 2. 00:07:56.520 --> 00:08:00.240 align:middle line:84% The average American household uses per year about 11,000 00:08:00.240 --> 00:08:02.550 align:middle line:90% kilowatt hours in electricity. 00:08:02.550 --> 00:08:07.050 align:middle line:84% Each person uses 300 million BTUs total 00:08:07.050 --> 00:08:11.400 align:middle line:84% per year, which is approximately 2.3 gallons of oil, 00:08:11.400 --> 00:08:15.300 align:middle line:84% 7.89 pounds of coal, and 252 cubic feet 00:08:15.300 --> 00:08:17.495 align:middle line:90% of natural gas per day. 00:08:17.495 --> 00:08:18.870 align:middle line:84% Now, it's just worth pointing out 00:08:18.870 --> 00:08:21.930 align:middle line:84% that the first example, in terms of the American household, 00:08:21.930 --> 00:08:25.530 align:middle line:84% is in kilowatt-hours but only counts for electricity. 00:08:25.530 --> 00:08:27.880 align:middle line:84% That's for the whole household per year. 00:08:27.880 --> 00:08:30.210 align:middle line:84% The second sentence measures each person 00:08:30.210 --> 00:08:35.250 align:middle line:84% on a per-capita basis but then breaks the millions of BTUs 00:08:35.250 --> 00:08:38.250 align:middle line:84% into different units because of the different sources 00:08:38.250 --> 00:08:39.159 align:middle line:90% of energy. 00:08:39.159 --> 00:08:41.970 align:middle line:84% And this is to say that, when we do these comparisons, 00:08:41.970 --> 00:08:44.400 align:middle line:84% we want to be careful about the units we use, 00:08:44.400 --> 00:08:47.610 align:middle line:84% the averaging over time, and the sources of energy, 00:08:47.610 --> 00:08:49.830 align:middle line:84% because the original source of energy 00:08:49.830 --> 00:08:52.780 align:middle line:84% may not actually be how much energy we use in the end. 00:08:52.780 --> 00:08:56.850 align:middle line:84% And we'll talk about that more in a few slides. 00:08:56.850 --> 00:08:59.270 align:middle line:84% Another key physical concept we have to talk about 00:08:59.270 --> 00:09:02.540 align:middle line:84% or will be very useful is power, and that's 00:09:02.540 --> 00:09:05.240 align:middle line:84% the quantitative rate of doing work. 00:09:05.240 --> 00:09:09.650 align:middle line:84% That is power is energy per time. 00:09:09.650 --> 00:09:11.000 align:middle line:90% It's a rate. 00:09:11.000 --> 00:09:13.700 align:middle line:84% The units we use of that are watts, 00:09:13.700 --> 00:09:16.340 align:middle line:90% or equal to joules per second. 00:09:16.340 --> 00:09:20.150 align:middle line:84% Other forms of power that you might be familiar with 00:09:20.150 --> 00:09:24.860 align:middle line:84% are ergs, amperes in terms of electrical current, horsepower 00:09:24.860 --> 00:09:29.220 align:middle line:84% in terms of the engine in your car or other motors, 00:09:29.220 --> 00:09:34.080 align:middle line:84% and lumens are the amount of energy passed off 00:09:34.080 --> 00:09:36.900 align:middle line:84% per second from an LED light bulb 00:09:36.900 --> 00:09:39.362 align:middle line:84% but measured over a sphere around a light bulb. 00:09:39.362 --> 00:09:41.820 align:middle line:84% So it's actually weighted by the area around the light bulb 00:09:41.820 --> 00:09:48.590 align:middle line:84% or what degree of area is putting out how much energy. 00:09:48.590 --> 00:09:52.790 align:middle line:84% So to just use the same example as the previous slide, 00:09:52.790 --> 00:09:54.790 align:middle line:84% you could say, I worked out for an hour, 00:09:54.790 --> 00:09:57.640 align:middle line:84% and I only worked off the equivalent of three Oreos. 00:09:57.640 --> 00:09:59.980 align:middle line:84% But maybe it sounds perhaps more impressive 00:09:59.980 --> 00:10:02.770 align:middle line:84% if you say, "My workout maintained a steady power 00:10:02.770 --> 00:10:07.220 align:middle line:90% output of three Oreos per hour!" 00:10:07.220 --> 00:10:09.280 align:middle line:84% Another key concept we have to cover 00:10:09.280 --> 00:10:12.640 align:middle line:84% that links energy and climate is emissions intensity. 00:10:12.640 --> 00:10:16.300 align:middle line:84% And emissions are measured in terms of greenhouse gases, 00:10:16.300 --> 00:10:19.970 align:middle line:84% usually measured in metric-ton carbon dioxide equivalent, 00:10:19.970 --> 00:10:26.153 align:middle line:84% which is abbreviated MTCDE, or mt-CO2-e, and so on. 00:10:26.153 --> 00:10:27.820 align:middle line:84% And the reason why we have to measure it 00:10:27.820 --> 00:10:31.390 align:middle line:84% in terms of metric-ton carbon dioxide equivalent 00:10:31.390 --> 00:10:33.760 align:middle line:84% is that there's a lot of different greenhouse gases, 00:10:33.760 --> 00:10:37.180 align:middle line:84% and some of them, for example, methane, CH4, 00:10:37.180 --> 00:10:40.640 align:middle line:84% has much more global warming potential than carbon dioxide. 00:10:40.640 --> 00:10:45.160 align:middle line:84% So a single ton of methane has about 84 times 00:10:45.160 --> 00:10:49.420 align:middle line:84% the global warming potential of a ton of carbon dioxide 00:10:49.420 --> 00:10:50.440 align:middle line:90% early in its life. 00:10:50.440 --> 00:10:53.980 align:middle line:84% That declines over time to about 20 metric tons 00:10:53.980 --> 00:10:55.420 align:middle line:90% of carbon dioxide equivalent. 00:10:55.420 --> 00:10:58.750 align:middle line:84% So this is just to say that, if we have different greenhouse 00:10:58.750 --> 00:11:01.030 align:middle line:84% gases, we measure them or make them 00:11:01.030 --> 00:11:03.070 align:middle line:84% all equivalent to a metric ton of carbon 00:11:03.070 --> 00:11:06.540 align:middle line:84% dioxide equivalent during their lifetime. 00:11:06.540 --> 00:11:10.740 align:middle line:84% We can also measure emissions intensity by the type of gas, 00:11:10.740 --> 00:11:13.830 align:middle line:84% as the example I just gave you in terms of methane, 00:11:13.830 --> 00:11:17.190 align:middle line:84% also nitrous oxide and fluorohexane, I think, 00:11:17.190 --> 00:11:19.020 align:middle line:90% are another greenhouse gas. 00:11:19.020 --> 00:11:22.320 align:middle line:84% You can measure in emissions intensity per unit of energy. 00:11:22.320 --> 00:11:24.330 align:middle line:84% This much greenhouse gas is created 00:11:24.330 --> 00:11:26.730 align:middle line:90% in terms of this much energy. 00:11:26.730 --> 00:11:29.580 align:middle line:84% You can measure greenhouse gases per activity, 00:11:29.580 --> 00:11:31.740 align:middle line:90% per dollar of GDP, or by region. 00:11:31.740 --> 00:11:33.810 align:middle line:84% People use lots of different intensities. 00:11:33.810 --> 00:11:35.227 align:middle line:84% And the reason why I want to focus 00:11:35.227 --> 00:11:37.200 align:middle line:84% on this key concept of intensity is 00:11:37.200 --> 00:11:39.460 align:middle line:84% that, as we look at different parts of the system, 00:11:39.460 --> 00:11:40.620 align:middle line:84% we're going to look at the intensity 00:11:40.620 --> 00:11:42.120 align:middle line:84% of the different parts of the system 00:11:42.120 --> 00:11:45.090 align:middle line:84% to get a whole picture of where greenhouse gases are coming 00:11:45.090 --> 00:11:47.910 align:middle line:84% from, just like we're going to look at energy intensity 00:11:47.910 --> 00:11:49.620 align:middle line:84% in terms of how much energy do you need 00:11:49.620 --> 00:11:52.110 align:middle line:84% for different activities, how much energy do 00:11:52.110 --> 00:11:54.460 align:middle line:84% different regions of the world use. 00:11:54.460 --> 00:11:57.810 align:middle line:84% And so to give you a few examples of the Conference 00:11:57.810 --> 00:12:01.140 align:middle line:84% of the Parties, the COP meetings that the UN Framework 00:12:01.140 --> 00:12:05.700 align:middle line:84% Convention on Climate Change runs every year-- 00:12:05.700 --> 00:12:07.230 align:middle line:90% they have reporting inventory. 00:12:07.230 --> 00:12:11.460 align:middle line:84% And when every country which is party to the Paris Agreement 00:12:11.460 --> 00:12:14.173 align:middle line:84% has to report its greenhouse gas emissions and, frankly, 00:12:14.173 --> 00:12:16.590 align:middle line:84% the actions that they're taking to reduce their greenhouse 00:12:16.590 --> 00:12:17.410 align:middle line:90% gases. 00:12:17.410 --> 00:12:20.520 align:middle line:84% They have to measure or report their greenhouse gases in terms 00:12:20.520 --> 00:12:22.380 align:middle line:90% of a specific inventory format. 00:12:22.380 --> 00:12:24.040 align:middle line:90% So I have linked to that here. 00:12:24.040 --> 00:12:25.920 align:middle line:84% You can click on it, and you can see 00:12:25.920 --> 00:12:29.670 align:middle line:84% how countries report different kinds of greenhouse gases. 00:12:29.670 --> 00:12:32.010 align:middle line:84% It's because countries can only see 00:12:32.010 --> 00:12:36.100 align:middle line:84% the source of the activities that create greenhouse gases. 00:12:36.100 --> 00:12:39.030 align:middle line:84% So it's easier for us to measure how many barrels of oil 00:12:39.030 --> 00:12:42.990 align:middle line:84% we burned or how many short tons of coal we burned or, let's 00:12:42.990 --> 00:12:44.760 align:middle line:84% say, how much land use conversion has 00:12:44.760 --> 00:12:48.000 align:middle line:84% led to how much methane or how much carbon dioxide. 00:12:48.000 --> 00:12:52.200 align:middle line:84% We can also measure, let's say, our greenhouse gas emissions 00:12:52.200 --> 00:12:56.650 align:middle line:84% per unit of electricity because electricity comes from a grid. 00:12:56.650 --> 00:12:58.640 align:middle line:84% The grid is a technology we'll talk about a lot 00:12:58.640 --> 00:13:01.620 align:middle line:84% in in this class that mixes different sources of energy 00:13:01.620 --> 00:13:02.340 align:middle line:90% together. 00:13:02.340 --> 00:13:06.240 align:middle line:84% And so we try to get an average intensity of greenhouse gas 00:13:06.240 --> 00:13:08.280 align:middle line:84% emissions per unit of electricity 00:13:08.280 --> 00:13:10.050 align:middle line:90% in different regions. 00:13:10.050 --> 00:13:12.030 align:middle line:84% Another emissions intensity factor 00:13:12.030 --> 00:13:14.380 align:middle line:84% that people look at quite often is air quality. 00:13:14.380 --> 00:13:17.100 align:middle line:84% You can look at how many greenhouse gases or how 00:13:17.100 --> 00:13:21.150 align:middle line:84% much particulate matter is produced by certain activities, 00:13:21.150 --> 00:13:26.020 align:middle line:84% like vehicle miles traveled or number of cars on the road. 00:13:26.020 --> 00:13:28.270 align:middle line:84% So just to give you an example of what carbon emission 00:13:28.270 --> 00:13:31.900 align:middle line:84% intensity looks like, this is the carbon emission intensity 00:13:31.900 --> 00:13:36.160 align:middle line:84% of economies in 2018, and this is from Our World in Data. 00:13:36.160 --> 00:13:38.200 align:middle line:84% And you can see, actually, it's measured, 00:13:38.200 --> 00:13:42.940 align:middle line:84% on the bottom legend here, in terms of amount of kilograms 00:13:42.940 --> 00:13:47.530 align:middle line:84% of carbon dioxide equivalent, the carbon dioxide intensity, 00:13:47.530 --> 00:13:52.550 align:middle line:84% per dollar of GDP measured in international 2011 prices. 00:13:52.550 --> 00:13:55.060 align:middle line:84% And you can see, by that measure, actually, 00:13:55.060 --> 00:13:58.960 align:middle line:84% a lot of the developed world, such as Australia, Europe, 00:13:58.960 --> 00:14:01.870 align:middle line:84% North America, and parts of Latin America 00:14:01.870 --> 00:14:04.570 align:middle line:84% don't look very intense, if only because they 00:14:04.570 --> 00:14:06.310 align:middle line:84% don't produce that many greenhouse 00:14:06.310 --> 00:14:09.670 align:middle line:90% gases per dollar of GDP output. 00:14:09.670 --> 00:14:12.430 align:middle line:84% Now, like we talked about in the last class 00:14:12.430 --> 00:14:15.943 align:middle line:84% in terms of population, what does this hide? 00:14:15.943 --> 00:14:17.860 align:middle line:84% Well, there's a couple of things with the map. 00:14:17.860 --> 00:14:21.460 align:middle line:84% Sometimes the area of the map distorts the actual area 00:14:21.460 --> 00:14:22.720 align:middle line:90% or total emissions. 00:14:22.720 --> 00:14:25.300 align:middle line:84% Small places don't look like they have as much impact 00:14:25.300 --> 00:14:27.310 align:middle line:84% as big places, even though that really has 00:14:27.310 --> 00:14:28.960 align:middle line:90% nothing to do with the average. 00:14:28.960 --> 00:14:31.720 align:middle line:84% But the more important point from a map like this 00:14:31.720 --> 00:14:34.690 align:middle line:84% is that it hides the fact that the rich countries, 00:14:34.690 --> 00:14:38.500 align:middle line:84% like Australia, Europe, North America, and parts 00:14:38.500 --> 00:14:41.710 align:middle line:84% of Latin America, simply have much larger GDPs. 00:14:41.710 --> 00:14:47.450 align:middle line:84% So it looks like the carbon dioxide output per GDP is low. 00:14:47.450 --> 00:14:49.930 align:middle line:84% But if we look at the per-capita CO2 emissions, 00:14:49.930 --> 00:14:51.482 align:middle line:84% like the point at our last class, 00:14:51.482 --> 00:14:53.440 align:middle line:84% you can see that, for a relatively small number 00:14:53.440 --> 00:14:55.690 align:middle line:84% of people in those rich, developed countries, 00:14:55.690 --> 00:14:58.750 align:middle line:84% they have very high CO2 emissions per capita. 00:14:58.750 --> 00:15:01.738 align:middle line:84% And so your map basically changes diametrically. 00:15:01.738 --> 00:15:04.030 align:middle line:84% And you can see the difference between richer countries 00:15:04.030 --> 00:15:05.080 align:middle line:90% and poor countries. 00:15:05.080 --> 00:15:07.300 align:middle line:84% And overwhelmingly, the richer countries 00:15:07.300 --> 00:15:11.780 align:middle line:84% are more responsible for carbon dioxide emissions. 00:15:11.780 --> 00:15:15.320 align:middle line:84% If we look at this similarly in a scatterplot, 00:15:15.320 --> 00:15:17.390 align:middle line:84% you can, again, see that it looks 00:15:17.390 --> 00:15:19.555 align:middle line:84% like, on an emission intensity basis, 00:15:19.555 --> 00:15:21.680 align:middle line:84% India and the United States are not that different. 00:15:21.680 --> 00:15:23.900 align:middle line:84% Of course, the difference is, in terms 00:15:23.900 --> 00:15:26.990 align:middle line:84% of the output of the economy on a per-capita basis, 00:15:26.990 --> 00:15:29.360 align:middle line:84% the average person in the United States 00:15:29.360 --> 00:15:32.720 align:middle line:84% produces much more and inevitably consumes much more 00:15:32.720 --> 00:15:34.940 align:middle line:84% than your average person in India or Pakistan. 00:15:34.940 --> 00:15:38.810 align:middle line:84% So even though we have equivalent emissions intensity 00:15:38.810 --> 00:15:41.720 align:middle line:84% per dollar, we simply produce and consume 00:15:41.720 --> 00:15:43.700 align:middle line:84% much more in the richer countries. 00:15:43.700 --> 00:15:47.720 align:middle line:84% And I make this point because, after the Kyoto Protocol 00:15:47.720 --> 00:15:50.750 align:middle line:84% and after the George W. Bush administration 00:15:50.750 --> 00:15:52.700 align:middle line:84% chose to leave the Kyoto Protocol, 00:15:52.700 --> 00:15:55.640 align:middle line:84% one of their arguments was that the US actually 00:15:55.640 --> 00:15:59.180 align:middle line:84% had a lower carbon emission intensity, or at least 00:15:59.180 --> 00:16:01.610 align:middle line:84% a comparable carbon emission intensity, 00:16:01.610 --> 00:16:03.380 align:middle line:90% to some developing countries. 00:16:03.380 --> 00:16:06.770 align:middle line:84% Of course, this hid the fact that the United States 00:16:06.770 --> 00:16:11.400 align:middle line:84% is both richer and consumes much more and produces much more. 00:16:11.400 --> 00:16:15.050 align:middle line:84% So that's just a way to talk about what intensities may tell 00:16:15.050 --> 00:16:18.100 align:middle line:90% us and what they may hide also. 00:16:18.100 --> 00:16:20.140 align:middle line:84% Now I'll get to a really key diagram 00:16:20.140 --> 00:16:22.100 align:middle line:84% that I rather love in this class. 00:16:22.100 --> 00:16:25.870 align:middle line:84% So I'll start off this class by talking about Sankey diagrams. 00:16:25.870 --> 00:16:28.090 align:middle line:84% And you can find a Sankey diagram for the US 00:16:28.090 --> 00:16:31.180 align:middle line:84% and every state at this web link at part of the bottom 00:16:31.180 --> 00:16:34.090 align:middle line:84% from Lawrence Livermore National Laboratory. 00:16:34.090 --> 00:16:37.270 align:middle line:84% What a Sankey diagram is is basically a flow chart, 00:16:37.270 --> 00:16:39.638 align:middle line:84% and it's a flow chart between the sources on the left. 00:16:39.638 --> 00:16:41.680 align:middle line:84% And you can see all of our energy sources, solar, 00:16:41.680 --> 00:16:44.920 align:middle line:84% nuclear, hydro, wind, geothermal, natural gas, coal, 00:16:44.920 --> 00:16:46.480 align:middle line:90% biomass, and petroleum. 00:16:46.480 --> 00:16:50.080 align:middle line:84% And you can see all of the ultimate uses on the right. 00:16:50.080 --> 00:16:51.710 align:middle line:90% And the final-- 00:16:51.710 --> 00:16:53.710 align:middle line:84% I guess what we'd call final consumption is 00:16:53.710 --> 00:16:55.670 align:middle line:84% in residential buildings, commercial buildings, 00:16:55.670 --> 00:16:57.910 align:middle line:84% industrial buildings, and transportation. 00:16:57.910 --> 00:17:00.460 align:middle line:84% Of course, this final category here 00:17:00.460 --> 00:17:03.580 align:middle line:84% is also a kind of a statement about where does the energy go 00:17:03.580 --> 00:17:04.900 align:middle line:90% in the first place. 00:17:04.900 --> 00:17:09.250 align:middle line:84% Only about 50% of the energy or less that we actually 00:17:09.250 --> 00:17:14.410 align:middle line:84% burn from the original sources goes into these uses 00:17:14.410 --> 00:17:15.940 align:middle line:90% in these sectors. 00:17:15.940 --> 00:17:19.060 align:middle line:84% About, actually, looks like one third of the energy 00:17:19.060 --> 00:17:21.700 align:middle line:84% goes to what we call energy services. 00:17:21.700 --> 00:17:24.490 align:middle line:84% And rejected energy is the byproduct 00:17:24.490 --> 00:17:28.060 align:middle line:84% of that combustion, usually, that we don't capture 00:17:28.060 --> 00:17:29.410 align:middle line:90% for actual energy services. 00:17:29.410 --> 00:17:32.200 align:middle line:84% So to give you an example, you can see how-- 00:17:32.200 --> 00:17:35.920 align:middle line:84% I said before, the electric grid mixes many different types 00:17:35.920 --> 00:17:37.630 align:middle line:90% of energy sources-- 00:17:37.630 --> 00:17:42.520 align:middle line:84% solar, nuclear, hydro, wind, all these, natural gas, and coal 00:17:42.520 --> 00:17:44.470 align:middle line:90% all feed into the electric grid. 00:17:44.470 --> 00:17:46.930 align:middle line:84% But when we feed that energy into the electric grid, 00:17:46.930 --> 00:17:50.050 align:middle line:84% into power plants, we basically only take a fraction of it. 00:17:50.050 --> 00:17:52.750 align:middle line:84% It looks like about one third of the electricity, 00:17:52.750 --> 00:17:54.910 align:middle line:84% one third of the energy in those energy sources, 00:17:54.910 --> 00:17:57.980 align:middle line:84% actually goes to things like residential, commercial, 00:17:57.980 --> 00:17:58.750 align:middle line:90% and industrial. 00:17:58.750 --> 00:18:01.010 align:middle line:84% But about 2/3 of it gets rejected, 00:18:01.010 --> 00:18:03.550 align:middle line:84% which means that it's heat energy going out 00:18:03.550 --> 00:18:06.190 align:middle line:84% of the chimney of a coal-fired power plant, 00:18:06.190 --> 00:18:08.710 align:middle line:84% or might be energy lost in the electric grid that's 00:18:08.710 --> 00:18:10.570 align:middle line:84% simply lost because of the resistance 00:18:10.570 --> 00:18:12.580 align:middle line:90% of the electrical wires. 00:18:12.580 --> 00:18:14.830 align:middle line:84% And so this kind of graph, I actually 00:18:14.830 --> 00:18:17.380 align:middle line:84% find tremendously useful to summarize 00:18:17.380 --> 00:18:19.780 align:middle line:84% what the sources on the left are, 00:18:19.780 --> 00:18:22.810 align:middle line:84% the ultimate uses of the energy are on the right, 00:18:22.810 --> 00:18:24.913 align:middle line:84% and also some of the interim steps where 00:18:24.913 --> 00:18:26.830 align:middle line:84% we might be able to capture some of the energy 00:18:26.830 --> 00:18:29.320 align:middle line:84% back in terms of energy efficiency or at least 00:18:29.320 --> 00:18:31.570 align:middle line:84% think about how our intermediate technologies, 00:18:31.570 --> 00:18:34.180 align:middle line:84% like the electric grid, actually use energy 00:18:34.180 --> 00:18:37.240 align:middle line:84% and how much of the intrinsic energy in the fuel source 00:18:37.240 --> 00:18:38.770 align:middle line:90% are we using. 00:18:38.770 --> 00:18:41.290 align:middle line:84% To take one example from this graph, 00:18:41.290 --> 00:18:43.460 align:middle line:84% I think it does a really good job of showing you, 00:18:43.460 --> 00:18:45.520 align:middle line:84% for example, that electricity overwhelmingly 00:18:45.520 --> 00:18:47.860 align:middle line:84% goes into residential buildings, commercial buildings, 00:18:47.860 --> 00:18:51.185 align:middle line:84% and industrial buildings or industrial activities, 00:18:51.185 --> 00:18:53.560 align:middle line:84% but you can see that there is no link between electricity 00:18:53.560 --> 00:18:56.590 align:middle line:84% generation and transportation, so a very small orange line 00:18:56.590 --> 00:19:00.162 align:middle line:90% here, 0.02 quads. 00:19:00.162 --> 00:19:01.870 align:middle line:84% And once again, I should have pointed out 00:19:01.870 --> 00:19:04.570 align:middle line:84% is that the total US energy consumption in 2021 00:19:04.570 --> 00:19:06.400 align:middle line:90% was at 97 quads. 00:19:06.400 --> 00:19:09.580 align:middle line:84% It's pretty easy mentally to round that up to about 100. 00:19:09.580 --> 00:19:13.240 align:middle line:84% So this is actually 0.02%, roughly, 00:19:13.240 --> 00:19:16.300 align:middle line:84% of all the energy in the US or electricity 00:19:16.300 --> 00:19:17.710 align:middle line:90% is used for transportation. 00:19:17.710 --> 00:19:20.740 align:middle line:84% You can see, overwhelmingly, that the majority of energy 00:19:20.740 --> 00:19:26.440 align:middle line:84% for transportation, 24.3 quads, or about 24% going to the US, 00:19:26.440 --> 00:19:27.790 align:middle line:90% comes from petroleum. 00:19:27.790 --> 00:19:33.040 align:middle line:84% And originally, that came from about 35 quads of-- or 35% 00:19:33.040 --> 00:19:35.500 align:middle line:90% of our initial energy sources. 00:19:35.500 --> 00:19:37.270 align:middle line:84% And you can see some portion goes off 00:19:37.270 --> 00:19:38.650 align:middle line:90% to industrial activities. 00:19:38.650 --> 00:19:40.450 align:middle line:84% But the vast majority of the energy 00:19:40.450 --> 00:19:43.690 align:middle line:84% that drives our transportation system is petroleum. 00:19:43.690 --> 00:19:47.740 align:middle line:84% And you can see that, when we burn petroleum or gasoline 00:19:47.740 --> 00:19:49.900 align:middle line:84% in our internal combustion engines, 00:19:49.900 --> 00:19:53.170 align:middle line:84% a very small fraction-- it looks like about 20% of it-- 00:19:53.170 --> 00:19:56.530 align:middle line:84% is actually used for moving the car forward. 00:19:56.530 --> 00:19:59.950 align:middle line:84% About 80% of the energy actually goes out of the tailpipe 00:19:59.950 --> 00:20:03.790 align:middle line:84% either in the form of heat out of the tailpipe or else air 00:20:03.790 --> 00:20:04.360 align:middle line:90% resistance. 00:20:04.360 --> 00:20:06.530 align:middle line:84% That is not really what we are trying to do. 00:20:06.530 --> 00:20:10.440 align:middle line:84% We're trying to move goods and services and people around. 00:20:10.440 --> 00:20:12.257 align:middle line:84% And so this is just, again, a way 00:20:12.257 --> 00:20:14.590 align:middle line:84% of saying that there's lots of different kinds of Sankey 00:20:14.590 --> 00:20:15.220 align:middle line:90% diagrams. 00:20:15.220 --> 00:20:18.040 align:middle line:84% This is a nice one that it has proportional flows 00:20:18.040 --> 00:20:21.820 align:middle line:84% between sources, intermediate, transforming technologies, 00:20:21.820 --> 00:20:22.960 align:middle line:90% and usages. 00:20:22.960 --> 00:20:25.540 align:middle line:84% It also shows you what efficiency level 00:20:25.540 --> 00:20:27.880 align:middle line:84% is being achieved in these different sectors. 00:20:27.880 --> 00:20:30.170 align:middle line:84% This is essentially an accounting exercise, 00:20:30.170 --> 00:20:32.530 align:middle line:84% but if you can find a Sankey diagram for a given 00:20:32.530 --> 00:20:34.793 align:middle line:84% region or a city or a country, it 00:20:34.793 --> 00:20:36.460 align:middle line:84% gives you a really good picture of where 00:20:36.460 --> 00:20:40.160 align:middle line:84% the energy is coming from and where the energy is going to. 00:20:40.160 --> 00:20:42.020 align:middle line:84% So we want to use these Sankey diagrams 00:20:42.020 --> 00:20:45.500 align:middle line:84% to think about what our pathways are to deep decarbonization. 00:20:45.500 --> 00:20:48.090 align:middle line:84% Deep decarbonization-- I think I've said before, 00:20:48.090 --> 00:20:49.610 align:middle line:90% if I haven't said it before-- 00:20:49.610 --> 00:20:52.140 align:middle line:90% it is both a goal and a process. 00:20:52.140 --> 00:20:54.800 align:middle line:84% We know that climate science tells us-- 00:20:54.800 --> 00:20:58.730 align:middle line:84% the IPCC has told us through an exhaustive scientific process 00:20:58.730 --> 00:21:02.420 align:middle line:84% that we need to achieve net-zero anthropogenic greenhouse gas 00:21:02.420 --> 00:21:04.130 align:middle line:90% emissions by 2050. 00:21:04.130 --> 00:21:06.620 align:middle line:84% Deep decarbonization is both the goal 00:21:06.620 --> 00:21:09.680 align:middle line:84% of getting to net-zero emissions by 2050, 00:21:09.680 --> 00:21:11.120 align:middle line:90% and also, it's this process. 00:21:11.120 --> 00:21:13.880 align:middle line:84% We're decarbonizing for the next 28 years 00:21:13.880 --> 00:21:17.040 align:middle line:84% to lessen the effects of climate change. 00:21:17.040 --> 00:21:19.790 align:middle line:84% And so the first deep decarbonization plan 00:21:19.790 --> 00:21:22.040 align:middle line:90% started in 2015. 00:21:22.040 --> 00:21:24.740 align:middle line:84% The Deep Decarbonization Pathways Project 00:21:24.740 --> 00:21:26.600 align:middle line:84% started 2015 for a number of countries 00:21:26.600 --> 00:21:29.630 align:middle line:84% to try to think about what analytical or policy 00:21:29.630 --> 00:21:31.460 align:middle line:84% or technology pathways we needed. 00:21:31.460 --> 00:21:33.500 align:middle line:84% It was updated in this paper in 2020 00:21:33.500 --> 00:21:35.270 align:middle line:90% that you read for this class. 00:21:35.270 --> 00:21:38.180 align:middle line:84% That was quickly followed by the White House Mid-Century 00:21:38.180 --> 00:21:41.000 align:middle line:84% Strategy, which was the Obama administration's commitment 00:21:41.000 --> 00:21:44.390 align:middle line:84% to the Paris Agreement to reduce greenhouse gas emissions by 80% 00:21:44.390 --> 00:21:45.560 align:middle line:90% by 2050. 00:21:45.560 --> 00:21:48.230 align:middle line:84% But just four years later, you have a series of reports 00:21:48.230 --> 00:21:52.010 align:middle line:84% from academics and NGOs looking at ways 00:21:52.010 --> 00:21:54.750 align:middle line:84% to get to 100% reduction by 2050, 00:21:54.750 --> 00:21:59.310 align:middle line:84% which is what the IPCC says we need to do by 2050. 00:21:59.310 --> 00:22:02.240 align:middle line:84% And so the key thing I want to say in this class 00:22:02.240 --> 00:22:06.865 align:middle line:84% but also in the paper I referred to last time last week, 00:22:06.865 --> 00:22:08.240 align:middle line:84% the paper on deep decarbonization 00:22:08.240 --> 00:22:10.970 align:middle line:84% that I wrote recently, is that many of these plans 00:22:10.970 --> 00:22:13.170 align:middle line:84% agree what the technology pathways are. 00:22:13.170 --> 00:22:17.840 align:middle line:84% So we should focus as urban policy analysts 00:22:17.840 --> 00:22:19.520 align:middle line:84% and urban planners and people who work 00:22:19.520 --> 00:22:21.800 align:middle line:90% in cities on implementation. 00:22:21.800 --> 00:22:23.330 align:middle line:90% We should focus on geography. 00:22:23.330 --> 00:22:25.100 align:middle line:84% We should focus on the politics of it. 00:22:25.100 --> 00:22:28.220 align:middle line:84% And, frankly, as planners, we should look at the land use 00:22:28.220 --> 00:22:30.230 align:middle line:84% and built environment implications 00:22:30.230 --> 00:22:33.420 align:middle line:90% of deep decarbonization. 00:22:33.420 --> 00:22:37.050 align:middle line:84% So look at the Sankey diagram from Williams et al., 2020. 00:22:37.050 --> 00:22:42.775 align:middle line:84% They look at the reference case for energy use 00:22:42.775 --> 00:22:43.650 align:middle line:90% in the United States. 00:22:43.650 --> 00:22:46.380 align:middle line:84% And this is a reference case I think the Energy Information 00:22:46.380 --> 00:22:49.260 align:middle line:84% Administration puts out every year. 00:22:49.260 --> 00:22:50.700 align:middle line:84% You can see on the left-hand side 00:22:50.700 --> 00:22:53.250 align:middle line:84% that, overwhelmingly, the reference case, which 00:22:53.250 --> 00:22:55.320 align:middle line:84% is usually fairly conservative, shows 00:22:55.320 --> 00:22:57.540 align:middle line:84% that we will get most of our energy 00:22:57.540 --> 00:23:00.850 align:middle line:84% from-- we get most of our energy currently from uranium, coal, 00:23:00.850 --> 00:23:03.060 align:middle line:84% natural gas, a little bit from biomass, 00:23:03.060 --> 00:23:05.460 align:middle line:84% and a large portion from petroleum. 00:23:05.460 --> 00:23:08.160 align:middle line:84% You can see renewables here are relatively small-- 00:23:08.160 --> 00:23:10.860 align:middle line:84% geothermal, solar, wind, and hydro. 00:23:10.860 --> 00:23:13.890 align:middle line:84% And all the energy goes through the intermediate steps-- 00:23:13.890 --> 00:23:17.370 align:middle line:84% electricity generation, pipeline gas, petroleum refining 00:23:17.370 --> 00:23:19.350 align:middle line:90% outputs, or liquid fuels. 00:23:19.350 --> 00:23:21.300 align:middle line:84% It gets transmitted through the electric grid, 00:23:21.300 --> 00:23:23.220 align:middle line:84% and it ultimately goes to buildings, 00:23:23.220 --> 00:23:25.740 align:middle line:84% which are residential and commercial buildings together. 00:23:25.740 --> 00:23:28.500 align:middle line:84% It goes to industry, and it goes to transportation. 00:23:28.500 --> 00:23:30.690 align:middle line:84% Again, you can see here from buildings 00:23:30.690 --> 00:23:33.090 align:middle line:84% that, overwhelmingly, about half of the energy 00:23:33.090 --> 00:23:35.010 align:middle line:84% comes from the grid, and half the energy comes 00:23:35.010 --> 00:23:36.450 align:middle line:90% from pipeline gas. 00:23:36.450 --> 00:23:39.600 align:middle line:84% Transportation, almost all the energy we currently use 00:23:39.600 --> 00:23:42.720 align:middle line:90% comes from petroleum. 00:23:42.720 --> 00:23:47.070 align:middle line:84% And industry uses a variety of energy technologies and fuels. 00:23:47.070 --> 00:23:50.670 align:middle line:84% Now let's contrast that with the Williams paper on what 00:23:50.670 --> 00:23:53.980 align:middle line:84% a 100%-renewable-energy future would look like. 00:23:53.980 --> 00:23:55.960 align:middle line:84% There's a couple of things to notice here. 00:23:55.960 --> 00:23:59.100 align:middle line:84% First, all of our renewables, the 100% renewable sources 00:23:59.100 --> 00:24:02.940 align:middle line:84% we are going to need, have taken over completely-- geothermal, 00:24:02.940 --> 00:24:05.200 align:middle line:90% solar, wind, hydro, and biomass. 00:24:05.200 --> 00:24:09.000 align:middle line:84% There's no coal, no natural gas, and no petroleum. 00:24:09.000 --> 00:24:10.980 align:middle line:84% Overwhelmingly, about 2/3 of the energy 00:24:10.980 --> 00:24:12.880 align:middle line:84% will go through the electric grid. 00:24:12.880 --> 00:24:15.240 align:middle line:84% It will be generated as electricity, 00:24:15.240 --> 00:24:17.240 align:middle line:84% either goes through the grid or be 00:24:17.240 --> 00:24:19.590 align:middle line:84% used to produce hydrogen. Hydrogen will 00:24:19.590 --> 00:24:23.350 align:middle line:84% produce various liquid and gaseous fuels. 00:24:23.350 --> 00:24:25.890 align:middle line:84% And if you look at what the future looks like in 2050 00:24:25.890 --> 00:24:29.172 align:middle line:84% according to this paper or this technology pathway, 00:24:29.172 --> 00:24:31.380 align:middle line:84% you can see that buildings have to overwhelmingly get 00:24:31.380 --> 00:24:33.210 align:middle line:90% their energy from electricity. 00:24:33.210 --> 00:24:35.310 align:middle line:84% Industry will still use a variety of inputs, 00:24:35.310 --> 00:24:38.880 align:middle line:84% but all those inputs will be from intermediate steps that 00:24:38.880 --> 00:24:42.700 align:middle line:84% have transformed our renewable energy into the kinds of fuels 00:24:42.700 --> 00:24:44.580 align:middle line:84% we need to drive industrial processes. 00:24:44.580 --> 00:24:46.770 align:middle line:84% And you can see that transportation 00:24:46.770 --> 00:24:49.800 align:middle line:84% is going to come overwhelmingly from electric. 00:24:49.800 --> 00:24:52.190 align:middle line:84% About 50% of our energy in transportation 00:24:52.190 --> 00:24:53.190 align:middle line:90% will come from electric. 00:24:53.190 --> 00:24:56.340 align:middle line:84% Some of it will come from, I think, liquid fuels, 00:24:56.340 --> 00:24:59.970 align:middle line:84% and some will come from compressed gases, 00:24:59.970 --> 00:25:02.670 align:middle line:84% such as hydrogen and maybe natural gas 00:25:02.670 --> 00:25:07.710 align:middle line:84% or methane produced from renewable resources. 00:25:07.710 --> 00:25:09.870 align:middle line:84% And let's just look at the implications from this, 00:25:09.870 --> 00:25:13.290 align:middle line:84% and this is to read the numbers off those previous two graphs. 00:25:13.290 --> 00:25:15.630 align:middle line:84% And then you look at the power sector. 00:25:15.630 --> 00:25:18.120 align:middle line:84% You can see that petroleum, natural gas, and coal, 00:25:18.120 --> 00:25:22.290 align:middle line:84% as I said, have to be eliminated completely, 100%. 00:25:22.290 --> 00:25:25.950 align:middle line:84% Biomass has to grow by 3 and 1/2 times. 00:25:25.950 --> 00:25:28.800 align:middle line:84% Nuclear power, in the 100% renewable case, 00:25:28.800 --> 00:25:30.360 align:middle line:84% is actually eliminated completely 00:25:30.360 --> 00:25:33.240 align:middle line:84% because I think Williams et al. do not define nuclear 00:25:33.240 --> 00:25:34.980 align:middle line:90% as a renewable energy source. 00:25:34.980 --> 00:25:38.070 align:middle line:84% But the key things, the most dire, I think, 00:25:38.070 --> 00:25:41.250 align:middle line:84% or most challenging things we have to deal with 00:25:41.250 --> 00:25:46.110 align:middle line:84% are growing our solar energy share by about a factor of 46. 00:25:46.110 --> 00:25:49.860 align:middle line:84% We have to grow our share from wind by a factor of 27. 00:25:49.860 --> 00:25:52.920 align:middle line:84% Hydro and geothermal are going to be relatively small players 00:25:52.920 --> 00:25:54.150 align:middle line:90% in this forecast. 00:25:54.150 --> 00:25:56.980 align:middle line:84% And that's just for the electric power sector. 00:25:56.980 --> 00:25:59.220 align:middle line:84% If you look at buildings, residential/commercial, 00:25:59.220 --> 00:26:00.850 align:middle line:90% you can see two things. 00:26:00.850 --> 00:26:05.610 align:middle line:84% Not only does electricity have to decline in total use, 00:26:05.610 --> 00:26:08.430 align:middle line:84% but we have to completely eliminate natural gas. 00:26:08.430 --> 00:26:13.020 align:middle line:84% And we have to increase our use of biomass just slightly. 00:26:13.020 --> 00:26:14.970 align:middle line:84% Now, the key thing is that the reason 00:26:14.970 --> 00:26:17.670 align:middle line:84% why we're declining our total use of electricity 00:26:17.670 --> 00:26:18.888 align:middle line:90% is that it's more efficient. 00:26:18.888 --> 00:26:20.430 align:middle line:84% But at the same time, the electricity 00:26:20.430 --> 00:26:22.950 align:middle line:84% we do use is going to be used to do things 00:26:22.950 --> 00:26:25.170 align:middle line:84% that natural gas currently does, like we're 00:26:25.170 --> 00:26:28.590 align:middle line:84% going to get heating and cooling from electricity rather than 00:26:28.590 --> 00:26:30.760 align:middle line:90% from natural gas as we do now. 00:26:30.760 --> 00:26:32.252 align:middle line:84% And so this is one important point 00:26:32.252 --> 00:26:33.960 align:middle line:84% I want to highlight from Sankey diagrams. 00:26:33.960 --> 00:26:36.690 align:middle line:84% If you look at the total primary energy in buildings, 00:26:36.690 --> 00:26:39.428 align:middle line:84% it actually has to go down by about 50%. 00:26:39.428 --> 00:26:41.970 align:middle line:84% And this is the point I think I made in the last class, which 00:26:41.970 --> 00:26:46.170 align:middle line:84% is, if you look back here, the total amount of energy-- 00:26:46.170 --> 00:26:48.180 align:middle line:84% it looks like, I think, roughly 100 quads, 00:26:48.180 --> 00:26:51.460 align:middle line:84% also 100 exajoules I think is how this paper measures it. 00:26:51.460 --> 00:26:53.140 align:middle line:84% And if you look at the next slide, 00:26:53.140 --> 00:26:55.260 align:middle line:84% you can see that the width of these flows 00:26:55.260 --> 00:26:58.680 align:middle line:84% have gone down quite a bit, which is just to make the point 00:26:58.680 --> 00:27:00.510 align:middle line:84% that I think I said to you last week, which 00:27:00.510 --> 00:27:04.450 align:middle line:84% is that not only do our uses have to become more efficient, 00:27:04.450 --> 00:27:08.520 align:middle line:84% we also have to simply reduce the total amount we're using. 00:27:08.520 --> 00:27:10.890 align:middle line:84% And the remaining 50% have to become renewable. 00:27:10.890 --> 00:27:12.810 align:middle line:84% So we actually need a complete transformation 00:27:12.810 --> 00:27:15.510 align:middle line:84% of our energy system both on the consumption side 00:27:15.510 --> 00:27:17.690 align:middle line:90% and the production side. 00:27:17.690 --> 00:27:21.080 align:middle line:84% If you look at the Tong paper, this 00:27:21.080 --> 00:27:24.500 align:middle line:84% is going to shift a little bit to this question of existing 00:27:24.500 --> 00:27:26.060 align:middle line:90% energy infrastructure. 00:27:26.060 --> 00:27:29.840 align:middle line:84% This is a paper written in 2019 in Nature. 00:27:29.840 --> 00:27:31.940 align:middle line:84% And in this paper, they say our estimates 00:27:31.940 --> 00:27:36.110 align:middle line:84% suggest that little or no new CO2-emitting infrastructure 00:27:36.110 --> 00:27:38.990 align:middle line:84% can be commissioned, and that existing infrastructure may 00:27:38.990 --> 00:27:42.530 align:middle line:84% need to be retired early or be retrofitted with carbon capture 00:27:42.530 --> 00:27:45.530 align:middle line:84% and storage technology in order to meet the Paris Agreement 00:27:45.530 --> 00:27:46.680 align:middle line:90% climate goals. 00:27:46.680 --> 00:27:49.640 align:middle line:84% So this paper is basically going to show us that we have 00:27:49.640 --> 00:27:51.380 align:middle line:84% existing infrastructure-- obviously, 00:27:51.380 --> 00:27:53.707 align:middle line:84% the energy infrastructure that we use every day-- 00:27:53.707 --> 00:27:55.790 align:middle line:84% and if we want to meet our Paris Agreement climate 00:27:55.790 --> 00:27:57.920 align:middle line:84% goals, which is keeping, preferably, 00:27:57.920 --> 00:28:02.270 align:middle line:84% global average temperatures less than 1.5 degrees Celsius higher 00:28:02.270 --> 00:28:04.640 align:middle line:84% than pre-Industrial era, we actually 00:28:04.640 --> 00:28:08.630 align:middle line:84% need to build no more fossil fuel infrastructure, which 00:28:08.630 --> 00:28:10.280 align:middle line:90% is CO2-emitting infrastructure. 00:28:10.280 --> 00:28:12.920 align:middle line:84% And we may have to retire some of the energy infrastructure 00:28:12.920 --> 00:28:16.400 align:middle line:84% that we have early before it's planned lifetime. 00:28:16.400 --> 00:28:18.560 align:middle line:90% This is part of the struggle. 00:28:18.560 --> 00:28:20.270 align:middle line:84% This is why you have activists trying 00:28:20.270 --> 00:28:23.540 align:middle line:84% to retire coal-fired power plants 00:28:23.540 --> 00:28:26.990 align:middle line:84% and avoid building new pipelines and natural gas plants 00:28:26.990 --> 00:28:31.340 align:middle line:84% or having, let's say, gas bans for new appliances in parts 00:28:31.340 --> 00:28:34.352 align:middle line:84% of Massachusetts and California and other states. 00:28:34.352 --> 00:28:35.810 align:middle line:84% So just to show you what this looks 00:28:35.810 --> 00:28:38.717 align:middle line:84% like, all these categories in the legend here-- 00:28:38.717 --> 00:28:40.550 align:middle line:84% commercial buildings, residential buildings, 00:28:40.550 --> 00:28:42.633 align:middle line:84% international transport, road transport, industry, 00:28:42.633 --> 00:28:44.990 align:middle line:84% electricity-- these kinds of technologies 00:28:44.990 --> 00:28:48.500 align:middle line:84% have a natural lifetime in terms of they 00:28:48.500 --> 00:28:51.800 align:middle line:84% have a committed CO2 emission from existing 00:28:51.800 --> 00:28:53.460 align:middle line:90% and proposed infrastructure. 00:28:53.460 --> 00:28:55.700 align:middle line:84% And you can see that our existing infrastructure 00:28:55.700 --> 00:28:58.850 align:middle line:84% is overwhelmingly dominated by industry and electricity. 00:28:58.850 --> 00:29:01.070 align:middle line:84% And road transport is this blue wedge, 00:29:01.070 --> 00:29:03.325 align:middle line:84% and buildings are actually relatively small. 00:29:03.325 --> 00:29:04.700 align:middle line:84% And those are all things that are 00:29:04.700 --> 00:29:06.920 align:middle line:84% going to phase out naturally over time 00:29:06.920 --> 00:29:08.580 align:middle line:90% because infrastructure gets old. 00:29:08.580 --> 00:29:11.210 align:middle line:84% If you don't maintain it, and you don't rebuild it, 00:29:11.210 --> 00:29:14.160 align:middle line:84% then it wears out, and you can't use it anymore. 00:29:14.160 --> 00:29:16.340 align:middle line:84% We've had more proposed infrastructure, 00:29:16.340 --> 00:29:20.510 align:middle line:84% but that proposed infrastructure cannot be built if we need 00:29:20.510 --> 00:29:23.090 align:middle line:84% to try to meet our Paris Climate goals. 00:29:23.090 --> 00:29:27.020 align:middle line:84% At the same time, in the B panel here, we 00:29:27.020 --> 00:29:30.120 align:middle line:84% have the committed emissions from different countries. 00:29:30.120 --> 00:29:32.210 align:middle line:84% And you can see the lifetime of infrastructure 00:29:32.210 --> 00:29:36.440 align:middle line:84% in China is relatively long and a large portion 00:29:36.440 --> 00:29:39.110 align:middle line:84% of the future problem because so much of it 00:29:39.110 --> 00:29:41.000 align:middle line:90% has been built fairly recently. 00:29:41.000 --> 00:29:42.530 align:middle line:84% You can see the rest of the world 00:29:42.530 --> 00:29:47.060 align:middle line:84% is actually only about 2/3 of the problem that China poses. 00:29:47.060 --> 00:29:49.730 align:middle line:84% And, actually, the US has a relatively small future 00:29:49.730 --> 00:29:53.070 align:middle line:84% committed emissions because the nature of our technology. 00:29:53.070 --> 00:29:56.060 align:middle line:84% Of course, there's been many more proposed projects, 00:29:56.060 --> 00:30:00.172 align:middle line:84% but the point of this paper is that we cannot actually build 00:30:00.172 --> 00:30:02.630 align:middle line:84% the proposed infrastructure, and we may have to retire some 00:30:02.630 --> 00:30:05.990 align:middle line:84% of those existing infrastructure early to avoid going over 00:30:05.990 --> 00:30:08.010 align:middle line:90% our climate limits. 00:30:08.010 --> 00:30:10.700 align:middle line:84% So another kind of interesting graph in this paper which 00:30:10.700 --> 00:30:12.920 align:middle line:84% I like quite a bit is a population pyramid, 00:30:12.920 --> 00:30:15.830 align:middle line:84% but it's a population pyramid showing 00:30:15.830 --> 00:30:19.520 align:middle line:84% the proportions of the population of people by age. 00:30:19.520 --> 00:30:21.290 align:middle line:84% It actually shows the age structure 00:30:21.290 --> 00:30:23.480 align:middle line:84% of our global electricity-generating 00:30:23.480 --> 00:30:24.500 align:middle line:90% capacity. 00:30:24.500 --> 00:30:26.930 align:middle line:84% And I want to simply make a point about what 00:30:26.930 --> 00:30:30.290 align:middle line:84% the different nature of the problem in China and the US 00:30:30.290 --> 00:30:30.890 align:middle line:90% are. 00:30:30.890 --> 00:30:33.380 align:middle line:84% You can see on the left-hand side-- 00:30:33.380 --> 00:30:35.720 align:middle line:84% this is the rest of the world, in some ways, 00:30:35.720 --> 00:30:36.750 align:middle line:90% dominated by the US. 00:30:36.750 --> 00:30:39.170 align:middle line:84% You can see around 15 or 17 years ago, 00:30:39.170 --> 00:30:42.020 align:middle line:84% we've built quite a bit of natural gas or oil 00:30:42.020 --> 00:30:43.465 align:middle line:90% infrastructure. 00:30:43.465 --> 00:30:44.840 align:middle line:84% You can see the rest of the world 00:30:44.840 --> 00:30:47.450 align:middle line:84% has more recently been building gas and oil 00:30:47.450 --> 00:30:49.293 align:middle line:84% infrastructure, these yellow bars. 00:30:49.293 --> 00:30:50.960 align:middle line:84% And you can see on the right-hand side-- 00:30:50.960 --> 00:30:54.230 align:middle line:84% this is electricity generation from coal, 00:30:54.230 --> 00:30:57.080 align:middle line:84% and that is overwhelmingly dominated by coal-fired power 00:30:57.080 --> 00:31:01.560 align:middle line:84% plants built in China mostly in the last 12 or 14 years. 00:31:01.560 --> 00:31:03.080 align:middle line:84% The reason why we use this graph is 00:31:03.080 --> 00:31:04.580 align:middle line:84% to look at the nature of the problem 00:31:04.580 --> 00:31:07.443 align:middle line:84% and what particular sectors we're going to have to tackle 00:31:07.443 --> 00:31:09.110 align:middle line:84% or which particular power plants we have 00:31:09.110 --> 00:31:13.310 align:middle line:84% to tackle to avoid creating more greenhouse gas emissions that, 00:31:13.310 --> 00:31:16.340 align:middle line:84% again, will put us beyond our Paris Agreement targets, that 00:31:16.340 --> 00:31:23.230 align:middle line:84% will then finally jeopardize the climate of the planet. 00:31:23.230 --> 00:31:26.640 align:middle line:84% So this brings me to cities, which is-- 00:31:26.640 --> 00:31:29.700 align:middle line:84% numerous recent studies show that most US greenhouse gas 00:31:29.700 --> 00:31:31.440 align:middle line:84% emissions or global greenhouse gas 00:31:31.440 --> 00:31:34.140 align:middle line:84% emissions in some of these studies are from cities. 00:31:34.140 --> 00:31:36.660 align:middle line:84% But the key point of this literature I want to highlight 00:31:36.660 --> 00:31:38.520 align:middle line:84% is that the exact proportion depends 00:31:38.520 --> 00:31:41.270 align:middle line:90% on how and where you count. 00:31:41.270 --> 00:31:42.380 align:middle line:90% The Jones et al. 00:31:42.380 --> 00:31:45.740 align:middle line:84% 2018 paper and the Goldstein et al 2020 paper 00:31:45.740 --> 00:31:49.100 align:middle line:84% both find that higher incomes and lower population densities 00:31:49.100 --> 00:31:51.110 align:middle line:84% are highly correlated with higher carbon 00:31:51.110 --> 00:31:54.140 align:middle line:90% footprints and energy use. 00:31:54.140 --> 00:31:59.210 align:middle line:84% The Gurney et al 2018, 2020, and 2021 reports and papers 00:31:59.210 --> 00:32:01.910 align:middle line:84% find that a majority of road and fossil fuel 00:32:01.910 --> 00:32:05.978 align:middle line:84% infrastructure or use can be associated with cities. 00:32:05.978 --> 00:32:07.520 align:middle line:84% The Moran paper is quite interesting, 00:32:07.520 --> 00:32:11.420 align:middle line:84% and it finds that, both in China and the US, 00:32:11.420 --> 00:32:15.680 align:middle line:84% the largest 10 cities plus 5%, or the top 5%-- 00:32:15.680 --> 00:32:18.080 align:middle line:84% of suburban residents by income are 00:32:18.080 --> 00:32:20.570 align:middle line:84% responsible for more than a majority of the greenhouse 00:32:20.570 --> 00:32:23.960 align:middle line:84% gas emissions from both countries, China and the US, 00:32:23.960 --> 00:32:27.530 align:middle line:84% which is to say that, if we focused just on the largest 10 00:32:27.530 --> 00:32:31.272 align:middle line:84% cities and the most carbon-intensive suburbs, now 00:32:31.272 --> 00:32:33.230 align:middle line:84% we could actually make a significant difference 00:32:33.230 --> 00:32:35.450 align:middle line:84% in the greenhouse gas emissions of the countries. 00:32:35.450 --> 00:32:37.910 align:middle line:84% It is also kind of recapping the moral argument 00:32:37.910 --> 00:32:41.600 align:middle line:84% I made to you in the last class, which is that the richest 00:32:41.600 --> 00:32:46.250 align:middle line:84% people in both countries have a disproportionate responsibility 00:32:46.250 --> 00:32:48.860 align:middle line:84% to lower the greenhouse gas emissions just in the same way 00:32:48.860 --> 00:32:51.140 align:middle line:84% that the US has a disproportionate responsibility 00:32:51.140 --> 00:32:53.750 align:middle line:84% to lower its greenhouse gas emissions relative to the rest 00:32:53.750 --> 00:32:54.920 align:middle line:90% of the world. 00:32:54.920 --> 00:32:58.820 align:middle line:84% Finally, the Seto in the 2021 and the Wiedmann et al. 00:32:58.820 --> 00:33:02.373 align:middle line:84% papers, 2021, show different research and planning 00:33:02.373 --> 00:33:04.790 align:middle line:84% frameworks for how do we really count these greenhouse gas 00:33:04.790 --> 00:33:05.290 align:middle line:90% emissions. 00:33:05.290 --> 00:33:07.520 align:middle line:84% And so there's debate about how you count it, 00:33:07.520 --> 00:33:10.580 align:middle line:84% but there's this emerging consensus in the literature 00:33:10.580 --> 00:33:13.400 align:middle line:84% that cities are responsible for a large proportion 00:33:13.400 --> 00:33:16.380 align:middle line:84% of greenhouse gas emissions in many countries, 00:33:16.380 --> 00:33:18.830 align:middle line:90% including China and the US. 00:33:18.830 --> 00:33:20.630 align:middle line:84% Just to highlight a few of the key issues 00:33:20.630 --> 00:33:22.970 align:middle line:84% why it's hard to get an exact proportion, 00:33:22.970 --> 00:33:25.130 align:middle line:84% depends on different definitions of cities 00:33:25.130 --> 00:33:26.960 align:middle line:90% or what an urban area is. 00:33:26.960 --> 00:33:30.200 align:middle line:84% It depends which emissions you count, upstream emissions, 00:33:30.200 --> 00:33:34.610 align:middle line:84% like things that you import in the form of fuels or goods; 00:33:34.610 --> 00:33:37.490 align:middle line:84% downstream emissions, the things that you export out of the city 00:33:37.490 --> 00:33:39.920 align:middle line:84% or waste energy or waste products that 00:33:39.920 --> 00:33:42.170 align:middle line:84% go outside of the city; and goods and services. 00:33:42.170 --> 00:33:43.730 align:middle line:84% There's all different ways to count the emissions 00:33:43.730 --> 00:33:44.772 align:middle line:90% from all of these things. 00:33:44.772 --> 00:33:48.440 align:middle line:84% The C40 annual report that I assigned in the reading 00:33:48.440 --> 00:33:51.210 align:middle line:90% gets to some of these issues. 00:33:51.210 --> 00:33:53.090 align:middle line:84% Finally, some interesting questions 00:33:53.090 --> 00:33:55.220 align:middle line:84% that are not always accounted for-- cities 00:33:55.220 --> 00:33:56.800 align:middle line:84% clearly shape local microclimates. 00:33:56.800 --> 00:33:59.370 align:middle line:84% Do we count that as part of climate change, 00:33:59.370 --> 00:34:01.640 align:middle line:84% because that actually changes how people subsequently 00:34:01.640 --> 00:34:02.862 align:middle line:90% use energy in cities? 00:34:02.862 --> 00:34:04.820 align:middle line:84% And there's this kind of fundamental question-- 00:34:04.820 --> 00:34:06.380 align:middle line:90% how do you measure affluence? 00:34:06.380 --> 00:34:08.630 align:middle line:84% Do you measure in terms of wealth or income? 00:34:08.630 --> 00:34:11.449 align:middle line:84% I suspect if we measured these in different ways, 00:34:11.449 --> 00:34:14.000 align:middle line:84% you'd find different places responsible 00:34:14.000 --> 00:34:16.699 align:middle line:84% for different levels of greenhouse gas emissions. 00:34:16.699 --> 00:34:18.469 align:middle line:84% Just again, to kind of make this argument 00:34:18.469 --> 00:34:20.989 align:middle line:84% about how we measure things matters 00:34:20.989 --> 00:34:24.270 align:middle line:84% and also how intensity may show us a different picture, 00:34:24.270 --> 00:34:25.520 align:middle line:90% this is from the Gurney et al. 00:34:25.520 --> 00:34:26.960 align:middle line:90% 2020 paper. 00:34:26.960 --> 00:34:29.790 align:middle line:84% The left-hand panel shows absolute emissions. 00:34:29.790 --> 00:34:31.909 align:middle line:84% You can see the absolute emissions 00:34:31.909 --> 00:34:34.909 align:middle line:84% in this country basically almost identically 00:34:34.909 --> 00:34:37.940 align:middle line:84% mimics the spatial or urban spatial structure 00:34:37.940 --> 00:34:43.010 align:middle line:84% of the country, where all the red areas and the left coast 00:34:43.010 --> 00:34:46.400 align:middle line:84% are high concentrations of absolute emissions. 00:34:46.400 --> 00:34:48.500 align:middle line:84% Of course, if you measure on a per-capita basis, 00:34:48.500 --> 00:34:50.330 align:middle line:84% you might say, OK, out West, people 00:34:50.330 --> 00:34:52.088 align:middle line:90% are relatively inefficient. 00:34:52.088 --> 00:34:53.630 align:middle line:84% But we should also highlight the fact 00:34:53.630 --> 00:34:55.190 align:middle line:84% that there's these interrelationships 00:34:55.190 --> 00:34:57.060 align:middle line:90% between these two areas. 00:34:57.060 --> 00:35:00.140 align:middle line:84% Places out here in the West is a high concentration 00:35:00.140 --> 00:35:02.510 align:middle line:84% of fossil fuel production/generation. 00:35:02.510 --> 00:35:04.700 align:middle line:90% But where is that energy going? 00:35:04.700 --> 00:35:06.380 align:middle line:90% That energy is going to cities. 00:35:06.380 --> 00:35:11.090 align:middle line:84% And so we think back to MacKay's left-hand bar of consumption. 00:35:11.090 --> 00:35:13.770 align:middle line:84% I would argue to all the urban planners in the room-- 00:35:13.770 --> 00:35:16.730 align:middle line:84% and I've said this to my colleagues in city government-- 00:35:16.730 --> 00:35:18.920 align:middle line:84% that we should not be complacent about the fact 00:35:18.920 --> 00:35:22.640 align:middle line:84% that we think we have relatively low per-capita emissions 00:35:22.640 --> 00:35:23.420 align:middle line:90% in cities. 00:35:23.420 --> 00:35:25.460 align:middle line:84% We have to be responsible for the fact 00:35:25.460 --> 00:35:27.410 align:middle line:84% that energy is being used elsewhere, 00:35:27.410 --> 00:35:30.680 align:middle line:84% that we consume in the form of fuels, goods 00:35:30.680 --> 00:35:34.280 align:middle line:84% and services, food, and we export our waste also. 00:35:34.280 --> 00:35:36.170 align:middle line:84% So that is the place where cities 00:35:36.170 --> 00:35:38.750 align:middle line:84% can have a big impact on greenhouse gas emissions. 00:35:38.750 --> 00:35:40.760 align:middle line:84% But it may be a different kind of efficiency. 00:35:40.760 --> 00:35:43.700 align:middle line:84% We might have to think about how much we consume, 00:35:43.700 --> 00:35:47.150 align:middle line:84% why we consume energy, and how do we do it more efficiently, 00:35:47.150 --> 00:35:50.000 align:middle line:84% and, hopefully, ultimately reduce our consumption to meet 00:35:50.000 --> 00:35:52.665 align:middle line:90% our decarbonization goals. 00:35:52.665 --> 00:35:54.540 align:middle line:84% Finally, I'll just flash through the readings 00:35:54.540 --> 00:35:57.660 align:middle line:84% quickly because we'll talk about them more in class. 00:35:57.660 --> 00:36:00.780 align:middle line:84% The Hsu et al 2019 paper-- this is actually not my paper. 00:36:00.780 --> 00:36:03.480 align:middle line:84% It's written by a colleague, Angel Hsu 00:36:03.480 --> 00:36:05.250 align:middle line:90% at University of North Carolina. 00:36:05.250 --> 00:36:08.190 align:middle line:84% It is a research roadmap for how do we spend more time 00:36:08.190 --> 00:36:12.150 align:middle line:84% or how do we spend more thinking about quantifying the climate 00:36:12.150 --> 00:36:16.830 align:middle line:84% mitigation actions that nonstate or subnational governments 00:36:16.830 --> 00:36:17.520 align:middle line:90% could take. 00:36:17.520 --> 00:36:19.900 align:middle line:84% And this is getting at that measurement question. 00:36:19.900 --> 00:36:22.320 align:middle line:84% How are we going to measure greenhouse gas emissions? 00:36:22.320 --> 00:36:23.820 align:middle line:84% And how are we going to measure what 00:36:23.820 --> 00:36:25.813 align:middle line:90% action those entities take? 00:36:25.813 --> 00:36:27.480 align:middle line:84% And just to give you an example, there's 00:36:27.480 --> 00:36:31.560 align:middle line:84% different ways to count how cities take climate action 00:36:31.560 --> 00:36:33.330 align:middle line:90% in comparison to state targets. 00:36:33.330 --> 00:36:35.610 align:middle line:84% And those targets may be different still 00:36:35.610 --> 00:36:37.620 align:middle line:90% than national-level targets. 00:36:37.620 --> 00:36:40.530 align:middle line:84% And so there's a question-- are we going to double count? 00:36:40.530 --> 00:36:43.660 align:middle line:84% In some cases, or, actually, most cases, 00:36:43.660 --> 00:36:46.560 align:middle line:84% cities are more ambitious than their states. 00:36:46.560 --> 00:36:50.090 align:middle line:84% Cities are often more ambitious than national governments. 00:36:50.090 --> 00:36:52.290 align:middle line:84% We want to avoid double counting. 00:36:52.290 --> 00:36:53.520 align:middle line:90% We want to assume-- 00:36:53.520 --> 00:36:57.240 align:middle line:84% we want to count cities considering 00:36:57.240 --> 00:37:00.000 align:middle line:84% how those cities are going to act relative to cities 00:37:00.000 --> 00:37:01.270 align:middle line:90% without targets. 00:37:01.270 --> 00:37:03.240 align:middle line:90% So this paper will get at that. 00:37:03.240 --> 00:37:05.280 align:middle line:84% We'll just talk about more in class. 00:37:05.280 --> 00:37:08.010 align:middle line:84% And this brings me to this optional reading 00:37:08.010 --> 00:37:11.940 align:middle line:84% by Markolf et al., which is "Pledges and Progress." 00:37:11.940 --> 00:37:13.920 align:middle line:84% This is a Brookings Institution report. 00:37:13.920 --> 00:37:17.130 align:middle line:84% It looks at the 100 largest cities across nine states. 00:37:17.130 --> 00:37:20.430 align:middle line:84% They find that number of cities, these 100 cities, 00:37:20.430 --> 00:37:25.200 align:middle line:84% have all set fairly ambitious goals, everything on the blue 00:37:25.200 --> 00:37:26.940 align:middle line:90% here on the right. 00:37:26.940 --> 00:37:29.580 align:middle line:84% The parentheses shows you when they set the goal. 00:37:29.580 --> 00:37:32.430 align:middle line:84% And you can see Boston, where we are-- 00:37:32.430 --> 00:37:35.040 align:middle line:84% actually, Cambridge is also in the graph somewhere. 00:37:35.040 --> 00:37:37.230 align:middle line:84% But Boston, Massachusetts, in 2005-- 00:37:37.230 --> 00:37:40.410 align:middle line:84% so they're going to have an 80% reduction by 2050, 00:37:40.410 --> 00:37:46.620 align:middle line:84% as all of these cities did, also meeting the White House's 00:37:46.620 --> 00:37:49.140 align:middle line:90% targets in 2016. 00:37:49.140 --> 00:37:51.450 align:middle line:84% It's commensurate with the national targets in 2016. 00:37:51.450 --> 00:37:52.950 align:middle line:84% You can see a number of these cities 00:37:52.950 --> 00:37:55.740 align:middle line:84% here in the left have set less ambitious targets-- 00:37:55.740 --> 00:37:58.890 align:middle line:84% 50% reduction, let's say 40% reduction. 00:37:58.890 --> 00:38:02.200 align:middle line:84% But they may have more closer targets. 00:38:02.200 --> 00:38:04.290 align:middle line:84% So this might be an interim goal on the way 00:38:04.290 --> 00:38:07.710 align:middle line:84% to a more ambitious target down the road. 00:38:07.710 --> 00:38:10.410 align:middle line:84% But the take-home from this Markolf report-- 00:38:10.410 --> 00:38:12.012 align:middle line:84% and I'll let you look at your leisure 00:38:12.012 --> 00:38:13.470 align:middle line:84% because I think some of you will be 00:38:13.470 --> 00:38:15.503 align:middle line:84% quite interested in particular cities-- 00:38:15.503 --> 00:38:16.920 align:middle line:84% you can see what the difference is 00:38:16.920 --> 00:38:19.337 align:middle line:84% between their current emissions inventory and their target 00:38:19.337 --> 00:38:20.070 align:middle line:90% emissions. 00:38:20.070 --> 00:38:23.310 align:middle line:84% And you can see in the case of Chicago, Illinois, 00:38:23.310 --> 00:38:28.110 align:middle line:84% they set a 2015-- they had a 2015 greenhouse gas inventory. 00:38:28.110 --> 00:38:30.618 align:middle line:84% They had a target emission in the year of that inventory, 00:38:30.618 --> 00:38:32.160 align:middle line:84% and it looks like Chicago is emitting 00:38:32.160 --> 00:38:36.240 align:middle line:84% about 50% more emissions than they targeted in 2015. 00:38:36.240 --> 00:38:38.340 align:middle line:84% I actually find this report quite hopeful 00:38:38.340 --> 00:38:41.260 align:middle line:84% because it takes a serious look at all these cities and says, 00:38:41.260 --> 00:38:43.530 align:middle line:84% well, we should take cities seriously 00:38:43.530 --> 00:38:45.930 align:middle line:84% in terms of the climate action goals we're studying. 00:38:45.930 --> 00:38:47.800 align:middle line:84% But in order to take them seriously, 00:38:47.800 --> 00:38:50.310 align:middle line:84% we also have to hold them according to the plans 00:38:50.310 --> 00:38:51.280 align:middle line:90% that they're setting. 00:38:51.280 --> 00:38:53.970 align:middle line:84% So it looks like Boston is closer 00:38:53.970 --> 00:38:57.600 align:middle line:84% to its target of 10% higher inventory emissions 00:38:57.600 --> 00:39:00.810 align:middle line:90% than it had planned for in 2016. 00:39:00.810 --> 00:39:04.890 align:middle line:84% That 10% hopefully gives us-- or that inventory difference 00:39:04.890 --> 00:39:07.260 align:middle line:84% gives us a good place to target our actions. 00:39:07.260 --> 00:39:09.120 align:middle line:84% Other places, let's say, Los Angeles-- 00:39:09.120 --> 00:39:10.953 align:middle line:84% looks like it's actually ahead of its goals. 00:39:10.953 --> 00:39:14.190 align:middle line:84% It's actually 10% less in terms of greenhouse gas emissions 00:39:14.190 --> 00:39:16.110 align:middle line:90% than they planned for in 2013. 00:39:16.110 --> 00:39:19.830 align:middle line:84% So cities-- looks like almost overwhelmingly temperate cities 00:39:19.830 --> 00:39:22.800 align:middle line:84% except for Minneapolis, but all of these fairly 00:39:22.800 --> 00:39:24.420 align:middle line:84% temperate-region cities are doing 00:39:24.420 --> 00:39:25.830 align:middle line:90% better than they expected. 00:39:25.830 --> 00:39:27.810 align:middle line:90% Some of these cities here-- 00:39:27.810 --> 00:39:30.270 align:middle line:84% I guess Chicago is a cold climate city, 00:39:30.270 --> 00:39:31.860 align:middle line:90% and Tucson is the opposite. 00:39:31.860 --> 00:39:34.560 align:middle line:84% But for different reasons, Tucson and Chicago 00:39:34.560 --> 00:39:39.780 align:middle line:84% are wildly over the goals they set in 2014 and 2015. 00:39:39.780 --> 00:39:43.530 align:middle line:84% And so I'll just stop here, and I will talk more in class 00:39:43.530 --> 00:39:44.280 align:middle line:90% this week. 00:39:44.280 --> 00:39:46.500 align:middle line:84% We'll talk the results of our carbon calculators 00:39:46.500 --> 00:39:48.390 align:middle line:90% that you did for homework. 00:39:48.390 --> 00:39:50.880 align:middle line:84% We will put some questions for discussion on the board, 00:39:50.880 --> 00:39:52.770 align:middle line:84% and we'll just start our discussion. 00:39:52.770 --> 00:39:55.690 align:middle line:84% And we'll have some news items to talk about in class. 00:39:55.690 --> 00:39:56.740 align:middle line:90% Thank you very much. 00:39:56.740 --> 00:40:00.510 align:middle line:84% I hope you guys have a great rest of your weekend-- 00:40:00.510 --> 00:40:12.000 align:middle line:90%