WEBVTT 00:00:00.000 --> 00:00:02.390 align:middle line:90% [SQUEAKING] 00:00:02.390 --> 00:00:04.302 align:middle line:90% [RUSTLING] 00:00:04.302 --> 00:00:05.258 align:middle line:90% [CLICKING] 00:00:05.258 --> 00:00:10.530 align:middle line:90% 00:00:10.530 --> 00:00:11.880 align:middle line:90% DAVID HSU: My name is David Hsu. 00:00:11.880 --> 00:00:15.090 align:middle line:84% I'm a professor at MIT in the Department of Urban Studies 00:00:15.090 --> 00:00:16.230 align:middle line:90% and Planning. 00:00:16.230 --> 00:00:18.870 align:middle line:84% And this is another installment or another lecture 00:00:18.870 --> 00:00:21.690 align:middle line:84% in my series of lectures on urban energy 00:00:21.690 --> 00:00:23.710 align:middle line:90% systems and policy. 00:00:23.710 --> 00:00:26.160 align:middle line:84% Today, we're going to talk about the notion of energy 00:00:26.160 --> 00:00:27.750 align:middle line:90% efficiency. 00:00:27.750 --> 00:00:29.580 align:middle line:84% The notion of energy efficiency or the idea 00:00:29.580 --> 00:00:30.955 align:middle line:84% of energy efficiency is something 00:00:30.955 --> 00:00:32.729 align:middle line:84% I've worked on for a long time, and I 00:00:32.729 --> 00:00:35.940 align:middle line:84% think it's worth examining what energy efficiency is, 00:00:35.940 --> 00:00:38.970 align:middle line:84% what energy efficiency is not, and what it may or may not 00:00:38.970 --> 00:00:41.220 align:middle line:90% achieve. 00:00:41.220 --> 00:00:43.120 align:middle line:84% Materials for today are on the syllabus. 00:00:43.120 --> 00:00:45.000 align:middle line:84% You can link to all of them in the PDF 00:00:45.000 --> 00:00:48.100 align:middle line:90% if you have the PDF copies. 00:00:48.100 --> 00:00:50.560 align:middle line:84% And it's worth, I guess, starting today's lecture 00:00:50.560 --> 00:00:53.710 align:middle line:84% with this kind of profile of Bruno Latour. 00:00:53.710 --> 00:00:56.680 align:middle line:84% He's called here a post-truth philosopher. 00:00:56.680 --> 00:00:58.570 align:middle line:84% I actually don't think that captures 00:00:58.570 --> 00:01:00.048 align:middle line:90% what his work is about. 00:01:00.048 --> 00:01:02.590 align:middle line:84% He was quite influential in the time I was in graduate school 00:01:02.590 --> 00:01:04.599 align:middle line:84% and I think quite influential since in terms 00:01:04.599 --> 00:01:07.870 align:middle line:84% of talking about how humans interact with the natural world 00:01:07.870 --> 00:01:09.670 align:middle line:90% and environment. 00:01:09.670 --> 00:01:11.230 align:middle line:84% At the time, I was in graduate school 00:01:11.230 --> 00:01:12.670 align:middle line:90% in the '90s, and the author-- 00:01:12.670 --> 00:01:15.460 align:middle line:84% a lot of his work was focused on science and technology, 00:01:15.460 --> 00:01:17.800 align:middle line:84% namely, how science, scientific facts, 00:01:17.800 --> 00:01:19.715 align:middle line:84% and how technologies were produced. 00:01:19.715 --> 00:01:21.340 align:middle line:84% So he writes about the high speed rail. 00:01:21.340 --> 00:01:23.260 align:middle line:84% He writes about the early internet in France. 00:01:23.260 --> 00:01:25.570 align:middle line:84% He goes on to write about other topics 00:01:25.570 --> 00:01:28.480 align:middle line:84% about how do humans relate to the natural world. 00:01:28.480 --> 00:01:31.240 align:middle line:84% And so, in this magazine profile, 00:01:31.240 --> 00:01:34.420 align:middle line:84% The New York Times Magazine, they write in the subtitle, 00:01:34.420 --> 00:01:36.820 align:middle line:84% "He spent decades deconstructing the way that scientists 00:01:36.820 --> 00:01:38.230 align:middle line:90% claim their authority." 00:01:38.230 --> 00:01:41.440 align:middle line:84% A lot of his work is about how institutions and systems 00:01:41.440 --> 00:01:44.510 align:middle line:84% create kinds of knowledge or create certain cultures. 00:01:44.510 --> 00:01:47.440 align:middle line:84% So I would argue that he's not, perhaps, a "post-truth" 00:01:47.440 --> 00:01:49.920 align:middle line:84% philosopher as much as one who examines the systems 00:01:49.920 --> 00:01:52.630 align:middle line:84% and institutions that surround certain technologies. 00:01:52.630 --> 00:01:55.120 align:middle line:84% And that's a theme I want to bring forward in this class. 00:01:55.120 --> 00:01:57.460 align:middle line:84% I think you've probably heard me allude to this a number 00:01:57.460 --> 00:01:58.900 align:middle line:90% of times before. 00:01:58.900 --> 00:02:04.780 align:middle line:84% How we create institutions, how we create markets, policies-- 00:02:04.780 --> 00:02:07.600 align:middle line:84% those all shape how technologies develop. 00:02:07.600 --> 00:02:10.120 align:middle line:84% It's also relevant this week because Bruno Latour just 00:02:10.120 --> 00:02:11.930 align:middle line:90% died, actually, a few days ago. 00:02:11.930 --> 00:02:14.770 align:middle line:84% This is a obituary in The Guardian. 00:02:14.770 --> 00:02:18.070 align:middle line:84% You can read obituaries in other major newspapers. 00:02:18.070 --> 00:02:19.600 align:middle line:84% A lot of newspapers say that he's 00:02:19.600 --> 00:02:23.710 align:middle line:84% one of the most misunderstood French philosophers, 00:02:23.710 --> 00:02:26.365 align:middle line:84% but his work was inherently interdisciplinary. 00:02:26.365 --> 00:02:29.380 align:middle line:84% He does touch on how humans create 00:02:29.380 --> 00:02:32.020 align:middle line:84% what we consider to be objective scientific realities, 00:02:32.020 --> 00:02:35.930 align:middle line:84% but also how that shapes how we see the world. 00:02:35.930 --> 00:02:38.400 align:middle line:84% And so this is a theme I want to bring forward 00:02:38.400 --> 00:02:41.370 align:middle line:84% to talk about what is energy efficiency. 00:02:41.370 --> 00:02:43.320 align:middle line:84% We could take this very abstract definition. 00:02:43.320 --> 00:02:47.160 align:middle line:84% I kind of came up with this very pared-down definition 00:02:47.160 --> 00:02:49.680 align:middle line:84% that I thought nobody could possibly disagree with. 00:02:49.680 --> 00:02:52.680 align:middle line:84% It's the efficient provision of energy services. 00:02:52.680 --> 00:02:56.102 align:middle line:84% Instead of simply focusing on the efficient use of energy, 00:02:56.102 --> 00:02:57.810 align:middle line:84% I've tried to reposition it a little bit, 00:02:57.810 --> 00:03:00.720 align:middle line:84% focusing on the services we get from energy and also 00:03:00.720 --> 00:03:01.650 align:middle line:90% the provision. 00:03:01.650 --> 00:03:03.730 align:middle line:84% This energy does not come from nowhere. 00:03:03.730 --> 00:03:05.050 align:middle line:90% It comes from systems. 00:03:05.050 --> 00:03:08.490 align:middle line:84% So if we break down this pared-down definition 00:03:08.490 --> 00:03:12.000 align:middle line:84% of energy efficiency, we'll focus on services. 00:03:12.000 --> 00:03:15.630 align:middle line:84% We can question what the meaning of service is itself. 00:03:15.630 --> 00:03:18.450 align:middle line:84% What is a reasonable expectation of service? 00:03:18.450 --> 00:03:20.730 align:middle line:84% Here in North America, or at least where 00:03:20.730 --> 00:03:23.260 align:middle line:84% we're having this class this year, 00:03:23.260 --> 00:03:26.190 align:middle line:84% we expect to have energy fairly abundant 00:03:26.190 --> 00:03:27.750 align:middle line:90% and reliable and cheap. 00:03:27.750 --> 00:03:31.470 align:middle line:84% We expect to be able to get access to electricity any time 00:03:31.470 --> 00:03:32.820 align:middle line:90% we flick on a switch. 00:03:32.820 --> 00:03:36.700 align:middle line:84% We expect to be able to gas our car any time we need to. 00:03:36.700 --> 00:03:39.660 align:middle line:84% Of course, we know that, when those systems are disrupted, 00:03:39.660 --> 00:03:43.950 align:middle line:84% such as in a hurricane, as in Hurricane Ian, which Florida's 00:03:43.950 --> 00:03:46.890 align:middle line:84% just recovering from now, we know service can be disrupted. 00:03:46.890 --> 00:03:48.990 align:middle line:84% We know wildfire can disrupt service. 00:03:48.990 --> 00:03:52.080 align:middle line:84% And so this-- we don't expect it to happen 00:03:52.080 --> 00:03:54.780 align:middle line:84% in these, quote unquote, I guess, 00:03:54.780 --> 00:03:57.750 align:middle line:84% what we call "disasters" or "periodic disasters." 00:03:57.750 --> 00:03:59.370 align:middle line:84% But we also know these things happen 00:03:59.370 --> 00:04:00.960 align:middle line:84% fairly frequently and increasingly 00:04:00.960 --> 00:04:02.980 align:middle line:90% frequently in our older grid. 00:04:02.980 --> 00:04:04.860 align:middle line:84% So we have to ask ourselves for the future 00:04:04.860 --> 00:04:06.960 align:middle line:84% as we plan what our systems are going 00:04:06.960 --> 00:04:09.600 align:middle line:84% to look like in the future, what is the reasonable expectation 00:04:09.600 --> 00:04:11.770 align:middle line:90% of service? 00:04:11.770 --> 00:04:13.660 align:middle line:84% Of course, we also should recognize 00:04:13.660 --> 00:04:16.959 align:middle line:84% that our ideas about what energy services are 00:04:16.959 --> 00:04:19.209 align:middle line:84% will vary according to our expectations 00:04:19.209 --> 00:04:20.649 align:middle line:90% and norms and institutions. 00:04:20.649 --> 00:04:25.190 align:middle line:84% Those all vary by places, by people, and by culture. 00:04:25.190 --> 00:04:29.090 align:middle line:84% If we talk about energy, we have to ask ourselves, what counts? 00:04:29.090 --> 00:04:31.760 align:middle line:84% For example, if we consider renewable energy, 00:04:31.760 --> 00:04:34.520 align:middle line:84% we consider it renewable because we get essentially 00:04:34.520 --> 00:04:38.420 align:middle line:84% wind and solar energy from larger geophysical forces 00:04:38.420 --> 00:04:40.970 align:middle line:84% or from the Sun, which is essentially 00:04:40.970 --> 00:04:44.240 align:middle line:84% an infinite source of energy falling on the Earth, which 00:04:44.240 --> 00:04:46.155 align:middle line:90% also powers ecosystems. 00:04:46.155 --> 00:04:47.780 align:middle line:84% But consider where we draw the boundary 00:04:47.780 --> 00:04:49.610 align:middle line:90% for what we consider energy. 00:04:49.610 --> 00:04:53.390 align:middle line:84% We consider renewable resources to be essentially infinite 00:04:53.390 --> 00:04:55.420 align:middle line:90% because they come from the Sun. 00:04:55.420 --> 00:04:57.170 align:middle line:84% At the same time, we consider fossil fuels 00:04:57.170 --> 00:04:59.780 align:middle line:84% to be relatively finite, not only in 00:04:59.780 --> 00:05:02.510 align:middle line:84% the amount that's produced, but also, of course, the amount 00:05:02.510 --> 00:05:05.390 align:middle line:84% that the atmosphere can absorb of carbon dioxide 00:05:05.390 --> 00:05:07.520 align:middle line:84% or other greenhouse gas emissions. 00:05:07.520 --> 00:05:10.610 align:middle line:84% But also consider if we draw our boundary around cities. 00:05:10.610 --> 00:05:12.110 align:middle line:84% As I mentioned in the first lecture, 00:05:12.110 --> 00:05:14.870 align:middle line:84% we have upstream emissions, and we have downstream emissions. 00:05:14.870 --> 00:05:17.060 align:middle line:90% Consider trash. 00:05:17.060 --> 00:05:19.970 align:middle line:84% Trash was originally consumed materials. 00:05:19.970 --> 00:05:22.340 align:middle line:84% Those required energies to manufacture them, 00:05:22.340 --> 00:05:23.780 align:middle line:90% thus upstream emissions. 00:05:23.780 --> 00:05:25.760 align:middle line:84% We consider the place of consumption 00:05:25.760 --> 00:05:27.110 align:middle line:90% quite often to be cities. 00:05:27.110 --> 00:05:29.360 align:middle line:84% And then we consider the downstream emissions, 00:05:29.360 --> 00:05:31.250 align:middle line:84% the energy or the emissions associated 00:05:31.250 --> 00:05:32.720 align:middle line:90% with disposing of trash. 00:05:32.720 --> 00:05:34.910 align:middle line:84% If we trace through energy in the same way, 00:05:34.910 --> 00:05:37.370 align:middle line:84% there's obviously embodied emissions upstream. 00:05:37.370 --> 00:05:40.040 align:middle line:84% There is the consumption, what we consider to be consumption, 00:05:40.040 --> 00:05:41.360 align:middle line:90% in, let's say, cities. 00:05:41.360 --> 00:05:44.240 align:middle line:84% And then there's embodied energy going out with the trash. 00:05:44.240 --> 00:05:47.090 align:middle line:84% Of course, it requires energy to get rid of trash. 00:05:47.090 --> 00:05:50.060 align:middle line:84% Also, energy can be generated from trash, as 00:05:50.060 --> 00:05:51.920 align:middle line:90% in waste-to-energy incinerators. 00:05:51.920 --> 00:05:55.700 align:middle line:84% So how you account for what counts as energy matters, 00:05:55.700 --> 00:05:58.310 align:middle line:84% and how we think about energy efficiency. 00:05:58.310 --> 00:06:00.230 align:middle line:90% And, of course, provision-- 00:06:00.230 --> 00:06:03.780 align:middle line:84% like I said before, energy doesn't come from nowhere. 00:06:03.780 --> 00:06:07.230 align:middle line:84% It has to be provided by somebody or by some agency. 00:06:07.230 --> 00:06:10.950 align:middle line:84% We know that provision of energy is not equal to all people. 00:06:10.950 --> 00:06:15.020 align:middle line:84% We expect that we have access to as much abundant energy 00:06:15.020 --> 00:06:17.360 align:middle line:84% at a reasonable price as we want. 00:06:17.360 --> 00:06:21.930 align:middle line:84% That's clearly not true in some parts of even North America. 00:06:21.930 --> 00:06:25.340 align:middle line:84% Not everyone has enough money to pay the utility bills. 00:06:25.340 --> 00:06:27.440 align:middle line:84% And there's many issues raised by provision. 00:06:27.440 --> 00:06:30.380 align:middle line:84% Do we expect people to pay for all their energy? 00:06:30.380 --> 00:06:32.510 align:middle line:84% We obviously subsidize other activities 00:06:32.510 --> 00:06:35.360 align:middle line:84% and other aspects of life, other public goods, 00:06:35.360 --> 00:06:36.770 align:middle line:90% such as transportation. 00:06:36.770 --> 00:06:38.330 align:middle line:90% Why don't we subsidize energy? 00:06:38.330 --> 00:06:42.620 align:middle line:84% We have a system built where ratepayers or users pay 00:06:42.620 --> 00:06:44.498 align:middle line:90% for exactly how much they use. 00:06:44.498 --> 00:06:46.040 align:middle line:84% What does that mean for how much they 00:06:46.040 --> 00:06:47.242 align:middle line:90% pay for how much we invest? 00:06:47.242 --> 00:06:48.700 align:middle line:84% Or should we invest, in the future, 00:06:48.700 --> 00:06:50.090 align:middle line:90% in other kinds of energy? 00:06:50.090 --> 00:06:53.002 align:middle line:84% These are all questions about energy efficiency. 00:06:53.002 --> 00:06:54.710 align:middle line:84% So, again, this gets back to the question 00:06:54.710 --> 00:06:58.160 align:middle line:84% of how do we define efficiency, which brings me 00:06:58.160 --> 00:06:59.930 align:middle line:84% to the Elizabeth Shove article I assigned 00:06:59.930 --> 00:07:02.420 align:middle line:84% for today, which is titled, I think, quite usefully, 00:07:02.420 --> 00:07:04.820 align:middle line:84% "What is wrong with energy efficiency?" 00:07:04.820 --> 00:07:07.490 align:middle line:84% Just to summarize some of the critiques of energy efficiency 00:07:07.490 --> 00:07:10.640 align:middle line:84% in her article, the first one is that the recognition 00:07:10.640 --> 00:07:13.010 align:middle line:84% that energy efficiency is not going to meet 00:07:13.010 --> 00:07:14.960 align:middle line:90% climate change on its own. 00:07:14.960 --> 00:07:17.570 align:middle line:84% Even if we consider the theoretical limits of energy 00:07:17.570 --> 00:07:19.640 align:middle line:84% efficiency, as one of the other articles 00:07:19.640 --> 00:07:21.680 align:middle line:84% also considers, we also, I think, 00:07:21.680 --> 00:07:23.780 align:middle line:84% should recognize that we are unlikely to reach 00:07:23.780 --> 00:07:25.310 align:middle line:90% the theoretical limit. 00:07:25.310 --> 00:07:26.930 align:middle line:84% But even the theoretical limit is not 00:07:26.930 --> 00:07:31.040 align:middle line:84% going to reduce greenhouse gas emissions completely. 00:07:31.040 --> 00:07:32.875 align:middle line:84% Also, there's a question of rebound effects, 00:07:32.875 --> 00:07:35.000 align:middle line:84% and this is an area that's been studied quite a bit 00:07:35.000 --> 00:07:36.000 align:middle line:90% in literature. 00:07:36.000 --> 00:07:37.670 align:middle line:84% It's also called the Jevons paradox, 00:07:37.670 --> 00:07:39.320 align:middle line:84% after a British economist, who looked 00:07:39.320 --> 00:07:44.950 align:middle line:84% at the likely scarcity or the British Navy 00:07:44.950 --> 00:07:46.450 align:middle line:90% running out of coal. 00:07:46.450 --> 00:07:48.010 align:middle line:84% Of course, he studies this paradox 00:07:48.010 --> 00:07:52.420 align:middle line:84% and sees that the British Navy then transfers or changes over 00:07:52.420 --> 00:07:56.660 align:middle line:84% to oil for its ships and uses more energy than before. 00:07:56.660 --> 00:08:00.160 align:middle line:84% So it's kind of given this rebound effect also-- 00:08:00.160 --> 00:08:03.700 align:middle line:84% the idea that if you use more efficient technology, 00:08:03.700 --> 00:08:06.670 align:middle line:84% user expectations rebound, and people actually 00:08:06.670 --> 00:08:08.350 align:middle line:90% use more energy than before. 00:08:08.350 --> 00:08:12.400 align:middle line:84% Another simple example is, do we actually save energy 00:08:12.400 --> 00:08:13.330 align:middle line:90% in energy efficiency? 00:08:13.330 --> 00:08:14.860 align:middle line:90% We have a more efficient car. 00:08:14.860 --> 00:08:17.020 align:middle line:84% Do people feel less guilty or less, 00:08:17.020 --> 00:08:19.990 align:middle line:84% let's say, constrained to drive more 00:08:19.990 --> 00:08:22.780 align:middle line:84% if energy efficiency or gas prices are a constraining 00:08:22.780 --> 00:08:25.313 align:middle line:90% effect? 00:08:25.313 --> 00:08:27.230 align:middle line:84% There's also the critique of energy efficiency 00:08:27.230 --> 00:08:28.820 align:middle line:84% that it's simply improving the system 00:08:28.820 --> 00:08:32.120 align:middle line:84% rather than overhauling or rethinking the system 00:08:32.120 --> 00:08:32.900 align:middle line:90% completely. 00:08:32.900 --> 00:08:38.250 align:middle line:90% 00:08:38.250 --> 00:08:41.409 align:middle line:84% And, of course, the main point of Shove's article, 00:08:41.409 --> 00:08:44.062 align:middle line:84% which actually references Bruno Latour quite a bit, 00:08:44.062 --> 00:08:46.020 align:middle line:84% is that, when we think about energy efficiency, 00:08:46.020 --> 00:08:48.940 align:middle line:84% we're basically counting some things rather than others. 00:08:48.940 --> 00:08:51.750 align:middle line:84% This is what Bruno Latour calls purification. 00:08:51.750 --> 00:08:54.550 align:middle line:84% You basically purify the object of study. 00:08:54.550 --> 00:08:56.880 align:middle line:84% We focus on energy itself without thinking 00:08:56.880 --> 00:08:59.010 align:middle line:84% about all the political or social entanglements 00:08:59.010 --> 00:09:01.060 align:middle line:84% of the energy to get there in the first place. 00:09:01.060 --> 00:09:04.300 align:middle line:84% For example, we talk about reducing our oil use. 00:09:04.300 --> 00:09:06.090 align:middle line:84% We may not be focused necessarily 00:09:06.090 --> 00:09:08.580 align:middle line:84% on where the oil comes from, as in discussions 00:09:08.580 --> 00:09:11.820 align:middle line:84% of energy independence or energy dependence. 00:09:11.820 --> 00:09:16.560 align:middle line:84% If we are getting oil from Venezuela and Nigeria and Iran 00:09:16.560 --> 00:09:20.495 align:middle line:84% and Russia, as we quite often do in global oil markets, 00:09:20.495 --> 00:09:21.870 align:middle line:84% we're basically focused on making 00:09:21.870 --> 00:09:25.500 align:middle line:84% our use of oil more efficient without necessarily 00:09:25.500 --> 00:09:27.680 align:middle line:84% taking into account some of these other factors. 00:09:27.680 --> 00:09:30.180 align:middle line:84% So, obviously, discussions of national security 00:09:30.180 --> 00:09:32.970 align:middle line:84% often take into account the idea of energy efficiency 00:09:32.970 --> 00:09:35.820 align:middle line:84% as reducing our dependence on foreign sources of oil, 00:09:35.820 --> 00:09:38.530 align:middle line:84% is a phrase you'll hear quite often. 00:09:38.530 --> 00:09:40.965 align:middle line:84% And, finally, the main critique of energy efficiency 00:09:40.965 --> 00:09:42.840 align:middle line:84% that summarizes some of these other critiques 00:09:42.840 --> 00:09:47.430 align:middle line:84% is that it's essentially a status quo view of energy. 00:09:47.430 --> 00:09:50.820 align:middle line:84% It basically frames or bounds the problem in certain ways. 00:09:50.820 --> 00:09:54.490 align:middle line:84% It says that we expect to have a certain level of service. 00:09:54.490 --> 00:09:57.300 align:middle line:84% We may not take into account what our future rebound 00:09:57.300 --> 00:10:00.540 align:middle line:84% effects are or by simply maintaining the status quo, 00:10:00.540 --> 00:10:02.640 align:middle line:84% by framing the problem in a certain way, 00:10:02.640 --> 00:10:06.470 align:middle line:84% rather than radically rethinking the problem. 00:10:06.470 --> 00:10:08.220 align:middle line:84% MacKay takes a different approach. 00:10:08.220 --> 00:10:09.720 align:middle line:84% In going through these texts, I want 00:10:09.720 --> 00:10:12.840 align:middle line:84% to show you how the texts reflect different viewpoints 00:10:12.840 --> 00:10:14.670 align:middle line:90% or rhetorical framings. 00:10:14.670 --> 00:10:18.570 align:middle line:84% MacKay says in chapter 19, every big effort helps. 00:10:18.570 --> 00:10:20.610 align:middle line:84% We've established the UK's present lifestyle 00:10:20.610 --> 00:10:22.860 align:middle line:84% can't be sustained on its own renewables. 00:10:22.860 --> 00:10:25.680 align:middle line:84% So what are our options if we wish to get off fossil fuels 00:10:25.680 --> 00:10:26.940 align:middle line:90% and live sustainably? 00:10:26.940 --> 00:10:29.160 align:middle line:84% We can balance the energy budget either by reducing 00:10:29.160 --> 00:10:32.910 align:middle line:84% demand or increasing supply or, of course, by doing both. 00:10:32.910 --> 00:10:36.150 align:middle line:84% But he skips down to say in the second paragraph, 00:10:36.150 --> 00:10:37.410 align:middle line:90% "Have no illusions. 00:10:37.410 --> 00:10:40.080 align:middle line:84% To achieve our goal of getting off fossil fuels, 00:10:40.080 --> 00:10:43.620 align:middle line:84% these reductions in demand and increasing supply must be big." 00:10:43.620 --> 00:10:47.370 align:middle line:84% So his emphasis is that we have to do big things, 00:10:47.370 --> 00:10:50.340 align:middle line:84% that energy efficiency should basically 00:10:50.340 --> 00:10:52.920 align:middle line:84% reflect this sense, which is what matters 00:10:52.920 --> 00:10:55.680 align:middle line:84% is the total impact on the problem of energy use 00:10:55.680 --> 00:10:56.640 align:middle line:90% and climate. 00:10:56.640 --> 00:10:59.190 align:middle line:84% And if you had to characterize it as an equation, 00:10:59.190 --> 00:11:02.340 align:middle line:84% it's simply impact equals the volume of the problem times 00:11:02.340 --> 00:11:03.190 align:middle line:90% change. 00:11:03.190 --> 00:11:05.400 align:middle line:84% So, as he says, if everyone does a little, 00:11:05.400 --> 00:11:06.720 align:middle line:90% we'll only achieve a little. 00:11:06.720 --> 00:11:09.310 align:middle line:84% We need big changes in demand and supply. 00:11:09.310 --> 00:11:11.610 align:middle line:84% But if we make changes, we have to apply those changes 00:11:11.610 --> 00:11:16.570 align:middle line:84% to large volumes or the entirety of the problem. 00:11:16.570 --> 00:11:19.238 align:middle line:84% From the Cullen and Allwood papers, the 2010 papers, 00:11:19.238 --> 00:11:21.280 align:middle line:84% you see they use this equation a couple of times. 00:11:21.280 --> 00:11:25.210 align:middle line:84% The potential for saving energy is the scale of energy flow, 00:11:25.210 --> 00:11:27.280 align:middle line:84% and then multiplied times the difference 00:11:27.280 --> 00:11:30.070 align:middle line:84% between the target efficiency and the current efficiency. 00:11:30.070 --> 00:11:31.930 align:middle line:84% This fundamentally reflects a different view 00:11:31.930 --> 00:11:33.110 align:middle line:90% of energy efficiency. 00:11:33.110 --> 00:11:36.010 align:middle line:84% It matters how efficient we can get 00:11:36.010 --> 00:11:38.990 align:middle line:84% compared to our current level of efficiency. 00:11:38.990 --> 00:11:41.890 align:middle line:84% So what matters is the potential for energy savings measured 00:11:41.890 --> 00:11:43.270 align:middle line:90% versus current efficiency. 00:11:43.270 --> 00:11:45.250 align:middle line:84% The delta effect essentially just 00:11:45.250 --> 00:11:47.680 align:middle line:84% depends on this bracketed term, the difference 00:11:47.680 --> 00:11:50.510 align:middle line:84% between target efficiency and current efficiency. 00:11:50.510 --> 00:11:53.560 align:middle line:84% This is a very different view because, as Cullen and Allwood 00:11:53.560 --> 00:11:56.590 align:middle line:84% point out and I'll highlight later in one of the tables, 00:11:56.590 --> 00:12:00.550 align:middle line:84% that our current use of energy is only about 10% or 11% 00:12:00.550 --> 00:12:05.170 align:middle line:84% of the primary energy we consume is actually harvested or used 00:12:05.170 --> 00:12:06.670 align:middle line:90% as final services. 00:12:06.670 --> 00:12:09.850 align:middle line:84% So as they argue, if we can increase our energy efficiency, 00:12:09.850 --> 00:12:12.970 align:middle line:84% we can drastically reduce our use of primary energy 00:12:12.970 --> 00:12:15.590 align:middle line:90% or greenhouse gas emissions. 00:12:15.590 --> 00:12:18.030 align:middle line:84% If you look at how they characterize the problem, 00:12:18.030 --> 00:12:21.020 align:middle line:84% they also say up front in one of their papers, 00:12:21.020 --> 00:12:23.960 align:middle line:84% "The reasons for using energy more efficiently are clear." 00:12:23.960 --> 00:12:25.550 align:middle line:84% And then they go down to say there's 00:12:25.550 --> 00:12:27.830 align:middle line:84% this Kaya identity, which is essentially 00:12:27.830 --> 00:12:29.780 align:middle line:90% a product of four drivers-- 00:12:29.780 --> 00:12:33.150 align:middle line:84% population, per-capita wealth, energy use intensity, 00:12:33.150 --> 00:12:35.300 align:middle line:84% which is energy per unit of wealth, 00:12:35.300 --> 00:12:38.990 align:middle line:84% and carbon intensity, which is CO2 per unit of energy. 00:12:38.990 --> 00:12:41.540 align:middle line:84% And they go right to say, "The first two drivers 00:12:41.540 --> 00:12:44.120 align:middle line:84% are socioeconomic and are difficult to limit 00:12:44.120 --> 00:12:45.170 align:middle line:90% in practice." 00:12:45.170 --> 00:12:49.280 align:middle line:84% Getting back to the Bruno Latour view or Elizabeth Shove's 00:12:49.280 --> 00:12:51.380 align:middle line:84% critique of energy efficiency, we 00:12:51.380 --> 00:12:53.420 align:middle line:84% have to critique whether or not these first two 00:12:53.420 --> 00:12:56.160 align:middle line:84% drivers are, in fact, difficult to limit in practice. 00:12:56.160 --> 00:13:00.142 align:middle line:84% But also, when we often say that climate change is no longer 00:13:00.142 --> 00:13:02.600 align:middle line:84% a technical problem-- it's a social and political problem-- 00:13:02.600 --> 00:13:04.040 align:middle line:84% we have to question whether or not 00:13:04.040 --> 00:13:05.990 align:middle line:84% we can simply take these first two drivers 00:13:05.990 --> 00:13:08.060 align:middle line:90% and leave them off the table. 00:13:08.060 --> 00:13:10.490 align:middle line:84% They spend most of the time in their two papers, 00:13:10.490 --> 00:13:13.340 align:middle line:84% usefully, I think, focused on the third and fourth drivers, 00:13:13.340 --> 00:13:15.703 align:middle line:84% which are technical options, which, of course, require 00:13:15.703 --> 00:13:17.120 align:middle line:84% energy to be used more efficiently 00:13:17.120 --> 00:13:19.460 align:middle line:84% and the decarbonization of energy supplies, something 00:13:19.460 --> 00:13:21.090 align:middle line:84% we've talked a lot about in this class. 00:13:21.090 --> 00:13:23.100 align:middle line:84% But what I'm trying to re-emphasize in this class, 00:13:23.100 --> 00:13:25.683 align:middle line:84% and the reason why I started off by talking about Bruno Latour 00:13:25.683 --> 00:13:29.450 align:middle line:84% and Elizabeth Shove, is that we cannot avoid the entanglement 00:13:29.450 --> 00:13:31.440 align:middle line:84% of some of these technical issues with social 00:13:31.440 --> 00:13:33.420 align:middle line:90% and political context. 00:13:33.420 --> 00:13:36.830 align:middle line:84% And we have to address the social and economic drivers 00:13:36.830 --> 00:13:40.010 align:middle line:84% of energy consumption, namely, per-capita wealth 00:13:40.010 --> 00:13:43.830 align:middle line:84% and per-capita energy use in wealthy countries. 00:13:43.830 --> 00:13:47.610 align:middle line:84% Of course, they do go on to say that "significant socioeconomic 00:13:47.610 --> 00:13:51.030 align:middle line:84% barriers also limit the uptake of new efficient designs. 00:13:51.030 --> 00:13:54.300 align:middle line:84% These include market imperfections, 00:13:54.300 --> 00:13:57.090 align:middle line:84% such as a lack of adequate information and financing, 00:13:57.090 --> 00:13:59.340 align:middle line:84% higher perceived costs, and differential benefits 00:13:59.340 --> 00:14:00.720 align:middle line:90% to the owner and user." 00:14:00.720 --> 00:14:03.070 align:middle line:84% You will recognize many of these factors, 00:14:03.070 --> 00:14:05.820 align:middle line:84% including behavioral barriers, such as consumer trends 00:14:05.820 --> 00:14:06.660 align:middle line:90% and habits. 00:14:06.660 --> 00:14:08.940 align:middle line:84% You'll recognize many of these factors 00:14:08.940 --> 00:14:10.860 align:middle line:84% are things we identified in previous readings, 00:14:10.860 --> 00:14:13.770 align:middle line:84% such as the reading by Blumstein et al., 1980. 00:14:13.770 --> 00:14:15.330 align:middle line:84% As I said in the previous lecture, 00:14:15.330 --> 00:14:18.450 align:middle line:84% I teach that article every year because all those barriers 00:14:18.450 --> 00:14:19.260 align:middle line:90% still exist. 00:14:19.260 --> 00:14:22.060 align:middle line:84% There are still barriers that we need to overcome. 00:14:22.060 --> 00:14:24.420 align:middle line:84% But let's get into the meat of their analysis, 00:14:24.420 --> 00:14:27.290 align:middle line:84% if only because I think they do some useful 00:14:27.290 --> 00:14:30.330 align:middle line:84% defining in some ways, chunking the problem, 00:14:30.330 --> 00:14:34.530 align:middle line:84% breaking down the problem into a more practical set of problems. 00:14:34.530 --> 00:14:37.470 align:middle line:84% They make this distinction between convergent devices 00:14:37.470 --> 00:14:39.960 align:middle line:90% and passive systems. 00:14:39.960 --> 00:14:42.480 align:middle line:84% They classify things as energy sources 00:14:42.480 --> 00:14:45.270 align:middle line:84% where they essentially transform fuels. 00:14:45.270 --> 00:14:47.783 align:middle line:84% There's some fuel loss in going to refined fuels 00:14:47.783 --> 00:14:49.200 align:middle line:84% and electricity, for example, when 00:14:49.200 --> 00:14:51.690 align:middle line:84% we go from petroleum to gasoline, 00:14:51.690 --> 00:14:53.580 align:middle line:90% there's some fuel loss. 00:14:53.580 --> 00:14:54.930 align:middle line:90% If we go from coal-- 00:14:54.930 --> 00:14:56.820 align:middle line:84% we can't necessarily use coal in our homes, 00:14:56.820 --> 00:14:58.140 align:middle line:90% but we can use electricity. 00:14:58.140 --> 00:15:03.000 align:middle line:84% As we know, we lose energy to generation distribution. 00:15:03.000 --> 00:15:05.580 align:middle line:84% And then this goes all the way through to end-use conversion. 00:15:05.580 --> 00:15:08.250 align:middle line:84% What we ultimately want is a set of services. 00:15:08.250 --> 00:15:10.170 align:middle line:84% Let's say we want light in our homes. 00:15:10.170 --> 00:15:12.940 align:middle line:84% That light in our homes requires electricity. 00:15:12.940 --> 00:15:14.880 align:middle line:84% So we have to go through the set of losses 00:15:14.880 --> 00:15:16.500 align:middle line:84% to get to the end-use conversion. 00:15:16.500 --> 00:15:20.490 align:middle line:84% The end-use conversion converts electricity into light. 00:15:20.490 --> 00:15:23.250 align:middle line:84% And, as they say in the article, once things 00:15:23.250 --> 00:15:26.700 align:middle line:84% have converted to this end use, it's very hard 00:15:26.700 --> 00:15:27.820 align:middle line:90% to harvest them again. 00:15:27.820 --> 00:15:30.998 align:middle line:84% In other words, there's some final service that we want. 00:15:30.998 --> 00:15:33.540 align:middle line:84% There's some useful energy that goes into that final service, 00:15:33.540 --> 00:15:35.748 align:middle line:84% but there's a whole series of losses-- the fuel loss, 00:15:35.748 --> 00:15:38.820 align:middle line:84% the generation loss, generation distribution loss, conversion 00:15:38.820 --> 00:15:41.640 align:middle line:84% losses, and system losses, and that's the total losses. 00:15:41.640 --> 00:15:45.030 align:middle line:84% And they distinguish the final service as the thing we want. 00:15:45.030 --> 00:15:46.950 align:middle line:84% And passive systems are essentially 00:15:46.950 --> 00:15:49.590 align:middle line:84% systems that do not transform energy again. 00:15:49.590 --> 00:15:51.240 align:middle line:90% They receive energy at the end. 00:15:51.240 --> 00:15:55.780 align:middle line:84% They're essentially the nodes at the end of the system. 00:15:55.780 --> 00:15:57.900 align:middle line:84% Another way to look at energy use 00:15:57.900 --> 00:16:01.510 align:middle line:84% is that we have some historical level of energy use. 00:16:01.510 --> 00:16:05.027 align:middle line:84% We may have a lower, hopefully, level of current energy use. 00:16:05.027 --> 00:16:07.110 align:middle line:84% Note, as I've shown you before, current energy use 00:16:07.110 --> 00:16:09.233 align:middle line:84% is probably higher than it was historically. 00:16:09.233 --> 00:16:10.650 align:middle line:84% But the point they want to make is 00:16:10.650 --> 00:16:13.500 align:middle line:84% that we have potential to realize energy efficiency. 00:16:13.500 --> 00:16:15.323 align:middle line:84% We have our current level of energy use. 00:16:15.323 --> 00:16:17.490 align:middle line:84% There's some level of reduction in energy use, which 00:16:17.490 --> 00:16:18.210 align:middle line:90% is economic. 00:16:18.210 --> 00:16:20.580 align:middle line:84% In other words, it would actually save money 00:16:20.580 --> 00:16:25.350 align:middle line:84% or is cost effective to, say, use the energy by, let's say, 00:16:25.350 --> 00:16:28.090 align:middle line:84% deploying new technologies or policies. 00:16:28.090 --> 00:16:30.900 align:middle line:84% Having said that, our economic potential reduction-- here, 00:16:30.900 --> 00:16:32.430 align:middle line:90% about 40%-- 00:16:32.430 --> 00:16:34.410 align:middle line:84% is lower than our technical potential 00:16:34.410 --> 00:16:37.860 align:middle line:84% because, theoretically, we could reduce our energy use by 55%, 00:16:37.860 --> 00:16:40.290 align:middle line:84% it looks like here, if we applied 00:16:40.290 --> 00:16:42.450 align:middle line:90% every possible technology. 00:16:42.450 --> 00:16:44.670 align:middle line:84% But the difference between technical and economic 00:16:44.670 --> 00:16:47.280 align:middle line:84% potential is that some things are economically 00:16:47.280 --> 00:16:48.480 align:middle line:90% cost effective. 00:16:48.480 --> 00:16:50.280 align:middle line:84% Some things are technologically possible 00:16:50.280 --> 00:16:53.038 align:middle line:84% but not yet economically cost effective. 00:16:53.038 --> 00:16:55.080 align:middle line:84% So that's the difference between these two lines. 00:16:55.080 --> 00:16:56.790 align:middle line:84% And, of course, our theoretical potential 00:16:56.790 --> 00:17:00.870 align:middle line:84% is a theoretical calculation of about how these systems could 00:17:00.870 --> 00:17:03.840 align:middle line:84% possibly work most efficiently to reduce their energy 00:17:03.840 --> 00:17:05.640 align:middle line:90% consumption completely. 00:17:05.640 --> 00:17:08.140 align:middle line:84% And so these three distinctions-- economic, 00:17:08.140 --> 00:17:09.780 align:middle line:84% technical, theoretical potential-- 00:17:09.780 --> 00:17:13.380 align:middle line:84% are something you'll see quite often in energy efficiency. 00:17:13.380 --> 00:17:15.329 align:middle line:84% We also have the question, necessarily, 00:17:15.329 --> 00:17:17.339 align:middle line:84% how these potentials are calculated. 00:17:17.339 --> 00:17:19.589 align:middle line:84% Economic potential is obviously defined 00:17:19.589 --> 00:17:23.609 align:middle line:84% in terms of a certain set of market conditions now. 00:17:23.609 --> 00:17:25.980 align:middle line:84% Technical potential is based on a certain set 00:17:25.980 --> 00:17:28.200 align:middle line:90% of technologies that exist now. 00:17:28.200 --> 00:17:31.680 align:middle line:84% And theoretical potential is how we calculate the potential. 00:17:31.680 --> 00:17:35.190 align:middle line:84% But, obviously, a new technology or a different set of demands 00:17:35.190 --> 00:17:37.680 align:middle line:84% might actually reduce energy consumption just as much 00:17:37.680 --> 00:17:40.150 align:middle line:90% as these potentials. 00:17:40.150 --> 00:17:43.510 align:middle line:84% Having said that, again, you'll see these different definitions 00:17:43.510 --> 00:17:45.460 align:middle line:90% of potential used quite often. 00:17:45.460 --> 00:17:48.310 align:middle line:84% This is from the DOE Energy Efficiency Potential Studies 00:17:48.310 --> 00:17:49.270 align:middle line:90% Catalog. 00:17:49.270 --> 00:17:51.610 align:middle line:84% You'll see they draw it a different way. 00:17:51.610 --> 00:17:53.650 align:middle line:84% Technical potential is one circle. 00:17:53.650 --> 00:17:56.530 align:middle line:84% This is how much we could reduce energy use technically. 00:17:56.530 --> 00:17:59.080 align:middle line:84% Economic potential is a subset of that. 00:17:59.080 --> 00:18:01.690 align:middle line:84% Achievable potential is smaller still 00:18:01.690 --> 00:18:03.520 align:middle line:84% because that's considered, let's say, 00:18:03.520 --> 00:18:06.800 align:middle line:84% what's socially achievable or politically achievable, 00:18:06.800 --> 00:18:11.620 align:middle line:84% which is not the same thing as economically realizable, 00:18:11.620 --> 00:18:12.913 align:middle line:90% and then achievable. 00:18:12.913 --> 00:18:14.830 align:middle line:84% And then, finally, program potential-- there's 00:18:14.830 --> 00:18:17.680 align:middle line:84% a skepticism even from the Department of Energy 00:18:17.680 --> 00:18:20.860 align:middle line:84% about how effective social or government programs can be. 00:18:20.860 --> 00:18:22.570 align:middle line:84% The program potential is smaller than 00:18:22.570 --> 00:18:24.880 align:middle line:84% the technical, economic, or theoretically 00:18:24.880 --> 00:18:28.450 align:middle line:84% achievable potential for any given policy, technology, 00:18:28.450 --> 00:18:30.590 align:middle line:90% or market. 00:18:30.590 --> 00:18:33.050 align:middle line:84% But they do a useful catalog, I guess, 00:18:33.050 --> 00:18:35.960 align:middle line:84% showing studies at the utility level, 00:18:35.960 --> 00:18:38.840 align:middle line:84% showing that there's studies that-- 00:18:38.840 --> 00:18:41.670 align:middle line:84% economic and achievable electricity savings 00:18:41.670 --> 00:18:44.540 align:middle line:90% between 1% and 1.5%. 00:18:44.540 --> 00:18:47.540 align:middle line:84% They show that the utility performance is here, 00:18:47.540 --> 00:18:51.320 align:middle line:84% looks like maybe averaging around 0.5% to 1%. 00:18:51.320 --> 00:18:53.360 align:middle line:84% There's a higher achievable potential, 00:18:53.360 --> 00:18:56.158 align:middle line:84% and there's a higher economic potential, 00:18:56.158 --> 00:18:57.450 align:middle line:90% especially out here at the end. 00:18:57.450 --> 00:19:02.200 align:middle line:84% You can see they categorize 36, 38, and 50 studies. 00:19:02.200 --> 00:19:04.675 align:middle line:84% They also emphasize in this catalog 00:19:04.675 --> 00:19:07.370 align:middle line:84% that most studies focus on certain sectors. 00:19:07.370 --> 00:19:09.050 align:middle line:84% They focus on residential, industrial, 00:19:09.050 --> 00:19:11.160 align:middle line:90% and commercial sectors. 00:19:11.160 --> 00:19:14.490 align:middle line:84% They do much less focus on agriculture, distribution, 00:19:14.490 --> 00:19:18.850 align:middle line:84% irrigation, and street lighting, which brings us back 00:19:18.850 --> 00:19:22.960 align:middle line:84% to our Sankey diagram of the US economy in 2021. 00:19:22.960 --> 00:19:25.340 align:middle line:84% Here's our four major sectors here-- residential, 00:19:25.340 --> 00:19:26.813 align:middle line:90% commercial, industrial. 00:19:26.813 --> 00:19:28.480 align:middle line:84% You'll notice, in that previous diagram, 00:19:28.480 --> 00:19:31.240 align:middle line:84% they don't show transportation because we obviously 00:19:31.240 --> 00:19:33.790 align:middle line:84% have many ways to make transportation more efficient. 00:19:33.790 --> 00:19:36.040 align:middle line:84% But it's essentially considered somewhat different, 00:19:36.040 --> 00:19:38.470 align:middle line:84% partly because it's outside the jurisdiction of utilities. 00:19:38.470 --> 00:19:41.580 align:middle line:84% We know we directly fuel our vehicles. 00:19:41.580 --> 00:19:42.690 align:middle line:90% We pump gasoline. 00:19:42.690 --> 00:19:45.000 align:middle line:84% We think of that as essentially a different system 00:19:45.000 --> 00:19:47.770 align:middle line:84% than our system for energy efficiency for residential, 00:19:47.770 --> 00:19:49.620 align:middle line:84% commercial, industrial, which is largely 00:19:49.620 --> 00:19:52.700 align:middle line:90% governed by utility companies. 00:19:52.700 --> 00:19:55.160 align:middle line:84% What's useful, I think, about the Cullen and Allwood papers 00:19:55.160 --> 00:19:58.610 align:middle line:84% is a lot of diagrams that show how things connect. 00:19:58.610 --> 00:20:01.550 align:middle line:84% For example, they show that we have three possible energy 00:20:01.550 --> 00:20:04.730 align:middle line:84% sources here on the left-- oil, gas, and coal. 00:20:04.730 --> 00:20:07.310 align:middle line:84% We have three convergent technologies-- petrol engines, 00:20:07.310 --> 00:20:09.350 align:middle line:84% diesel engines, and electric motors. 00:20:09.350 --> 00:20:12.740 align:middle line:84% We have three modes of transportation-- cars, buses, 00:20:12.740 --> 00:20:13.670 align:middle line:90% and trains. 00:20:13.670 --> 00:20:15.670 align:middle line:84% And we have a final service that we want to get, 00:20:15.670 --> 00:20:17.000 align:middle line:90% which is passenger transport. 00:20:17.000 --> 00:20:19.730 align:middle line:84% The key thing about this horizontal slice 00:20:19.730 --> 00:20:21.710 align:middle line:84% through these various technologies 00:20:21.710 --> 00:20:24.650 align:middle line:84% is that some fuel sources or energy sources can only 00:20:24.650 --> 00:20:26.630 align:middle line:84% connect to certain conversion devices, which 00:20:26.630 --> 00:20:28.130 align:middle line:90% connect to certain vehicles. 00:20:28.130 --> 00:20:32.330 align:middle line:84% For example, oil can only produce petrol or diesel. 00:20:32.330 --> 00:20:35.750 align:middle line:84% We know we have car, bus, and train versions that 00:20:35.750 --> 00:20:40.370 align:middle line:84% use petrol or diesel to get passenger transport. 00:20:40.370 --> 00:20:42.290 align:middle line:84% But if we want to use an electric motor, 00:20:42.290 --> 00:20:45.530 align:middle line:84% we can only, in this paper, get our electricity 00:20:45.530 --> 00:20:47.450 align:middle line:90% from gas and coal sources. 00:20:47.450 --> 00:20:50.573 align:middle line:84% And we have to electrify our cars, buses, and trains. 00:20:50.573 --> 00:20:52.490 align:middle line:84% Of course, it's also worth thinking about what 00:20:52.490 --> 00:20:53.840 align:middle line:90% this chain leaves out. 00:20:53.840 --> 00:20:57.410 align:middle line:84% It obviously doesn't include something simple like walking. 00:20:57.410 --> 00:21:00.200 align:middle line:84% E-bikes or micromobility might use electric motors. 00:21:00.200 --> 00:21:02.000 align:middle line:84% But walking is not something that's 00:21:02.000 --> 00:21:03.960 align:middle line:90% counted as a energy source. 00:21:03.960 --> 00:21:06.800 align:middle line:84% It may fulfill our need for passenger transport, 00:21:06.800 --> 00:21:09.740 align:middle line:84% and it actually may fulfill other needs, like, let's say, 00:21:09.740 --> 00:21:12.320 align:middle line:84% increased psychological benefit or increased health. 00:21:12.320 --> 00:21:13.820 align:middle line:84% But that's not necessarily captured 00:21:13.820 --> 00:21:16.220 align:middle line:90% in how we measure these things. 00:21:16.220 --> 00:21:19.100 align:middle line:84% There's that often quoted saying-- 00:21:19.100 --> 00:21:21.980 align:middle line:84% you can't manage what you don't measure. 00:21:21.980 --> 00:21:24.320 align:middle line:84% These papers are all about measuring certain things 00:21:24.320 --> 00:21:26.190 align:middle line:84% and thinking about how to make them more efficient. 00:21:26.190 --> 00:21:27.982 align:middle line:84% Of course, when you measure certain things, 00:21:27.982 --> 00:21:29.540 align:middle line:84% you're not counting other things. 00:21:29.540 --> 00:21:31.130 align:middle line:84% I think it's attributed to Einstein, 00:21:31.130 --> 00:21:33.360 align:middle line:84% but it's not necessarily clear if he said it. 00:21:33.360 --> 00:21:37.790 align:middle line:84% He said, not everything that can be counted 00:21:37.790 --> 00:21:40.310 align:middle line:84% counts, and not everything that counts can be counted. 00:21:40.310 --> 00:21:41.810 align:middle line:84% That's not necessarily what he said, 00:21:41.810 --> 00:21:44.240 align:middle line:84% but it's a famous quote attributed to him. 00:21:44.240 --> 00:21:46.430 align:middle line:84% This is the point of energy efficiency also. 00:21:46.430 --> 00:21:48.740 align:middle line:84% We need to count certain things, but we also 00:21:48.740 --> 00:21:52.615 align:middle line:84% need to value some things that can't necessarily be counted. 00:21:52.615 --> 00:21:54.740 align:middle line:84% If you look at some of the vertical slices, though, 00:21:54.740 --> 00:21:58.058 align:middle line:84% there's some very useful back-of-the-envelope figures 00:21:58.058 --> 00:21:58.850 align:middle line:90% for you to look at. 00:21:58.850 --> 00:22:02.270 align:middle line:84% We have the total amount of energy use for an energy 00:22:02.270 --> 00:22:03.020 align:middle line:90% source. 00:22:03.020 --> 00:22:05.750 align:middle line:84% About the majority of it is used is-- 00:22:05.750 --> 00:22:08.690 align:middle line:84% more than half of it is used in direct fuel use. 00:22:08.690 --> 00:22:11.120 align:middle line:84% About 40% of it looks to be used in electricity. 00:22:11.120 --> 00:22:14.750 align:middle line:84% And a very small portion is used actually as heat directly. 00:22:14.750 --> 00:22:17.750 align:middle line:84% The energy sources are overwhelmingly oil and coal. 00:22:17.750 --> 00:22:20.450 align:middle line:84% This is from 2010, so it may be superseded. 00:22:20.450 --> 00:22:21.830 align:middle line:90% Gas is probably higher. 00:22:21.830 --> 00:22:23.390 align:middle line:90% Renewables are probably higher. 00:22:23.390 --> 00:22:26.670 align:middle line:84% Biomass and nuclear are probably roughly the same. 00:22:26.670 --> 00:22:29.480 align:middle line:84% In terms of conversion devices, we overwhelmingly 00:22:29.480 --> 00:22:32.630 align:middle line:84% use conversion devices for transforming energy 00:22:32.630 --> 00:22:35.210 align:middle line:84% are diesel engines, electric heaters, electric motors, 00:22:35.210 --> 00:22:38.490 align:middle line:84% and biomass burners and gas burners. 00:22:38.490 --> 00:22:40.350 align:middle line:84% If you look at the passive systems, 00:22:40.350 --> 00:22:43.680 align:middle line:84% appliances, heated and cooled space, heat systems, 00:22:43.680 --> 00:22:47.040 align:middle line:84% and driven systems dominate our passive systems. 00:22:47.040 --> 00:22:51.420 align:middle line:84% You can see if we break down our 475 exajoules of energy, 00:22:51.420 --> 00:22:53.940 align:middle line:84% buildings and factories are quite high. 00:22:53.940 --> 00:22:56.260 align:middle line:84% Vehicles are actually relatively low. 00:22:56.260 --> 00:22:58.020 align:middle line:84% But, of course, all these things mix in 00:22:58.020 --> 00:22:59.910 align:middle line:84% to get all of our final services. 00:22:59.910 --> 00:23:02.040 align:middle line:84% We need vehicles, we need buildings, 00:23:02.040 --> 00:23:03.730 align:middle line:84% we need factories all mixed together. 00:23:03.730 --> 00:23:07.050 align:middle line:84% So if you look at the breakdown of final services, 00:23:07.050 --> 00:23:09.750 align:middle line:84% you can see they try to clock by how we use our energy. 00:23:09.750 --> 00:23:12.390 align:middle line:84% Thermal comfort and sustenance are relatively high, 00:23:12.390 --> 00:23:13.920 align:middle line:84% but structure, freight transport, 00:23:13.920 --> 00:23:17.040 align:middle line:84% and passenger transport are still relatively high amounts 00:23:17.040 --> 00:23:19.500 align:middle line:84% of energy because they consume material, 00:23:19.500 --> 00:23:23.310 align:middle line:84% because they consume embodied energy, as well as direct fuel 00:23:23.310 --> 00:23:25.260 align:middle line:90% use. 00:23:25.260 --> 00:23:28.070 align:middle line:84% So one thing to point out of the Sankey diagram 00:23:28.070 --> 00:23:29.600 align:middle line:84% from the Cullen and Allwood paper 00:23:29.600 --> 00:23:32.270 align:middle line:84% is that some of these things are shown as flows, 00:23:32.270 --> 00:23:33.920 align:middle line:84% but through each these vertical slices, 00:23:33.920 --> 00:23:37.010 align:middle line:84% you can't necessarily trace energy all the way through. 00:23:37.010 --> 00:23:39.440 align:middle line:84% For example, if you go from oil, oil 00:23:39.440 --> 00:23:42.530 align:middle line:84% can only be used in diesel engines and petrol engines 00:23:42.530 --> 00:23:45.290 align:middle line:84% and oil burners, so we can account 00:23:45.290 --> 00:23:47.180 align:middle line:90% for all this direct fuel use. 00:23:47.180 --> 00:23:51.150 align:middle line:84% But we use some portion of oil, some portion of gas, 00:23:51.150 --> 00:23:53.750 align:middle line:84% coal, nuclear, renewables to generate electricity. 00:23:53.750 --> 00:23:56.660 align:middle line:84% But as you start to move through these vertical slices, 00:23:56.660 --> 00:23:59.060 align:middle line:84% it gets harder and harder to account for where 00:23:59.060 --> 00:24:01.040 align:middle line:90% these flows go directly. 00:24:01.040 --> 00:24:03.620 align:middle line:90% For example, let's take trucks. 00:24:03.620 --> 00:24:06.530 align:middle line:84% We go from diesel engines and petrol engines. 00:24:06.530 --> 00:24:10.250 align:middle line:84% They may map, to some extent, to cars and trucks. 00:24:10.250 --> 00:24:11.930 align:middle line:84% But you can see these flows don't quite 00:24:11.930 --> 00:24:14.030 align:middle line:84% line up because, across the vertical slices, 00:24:14.030 --> 00:24:16.760 align:middle line:84% it's very hard to account for how many diesel 00:24:16.760 --> 00:24:19.108 align:middle line:84% and how many petrol trucks we have. 00:24:19.108 --> 00:24:20.900 align:middle line:84% Having said that, we also know some portion 00:24:20.900 --> 00:24:23.120 align:middle line:84% of our trucks, planes, and ships and trains 00:24:23.120 --> 00:24:24.860 align:middle line:90% go with freight transport. 00:24:24.860 --> 00:24:26.810 align:middle line:84% They categorize these in various ways. 00:24:26.810 --> 00:24:29.540 align:middle line:84% How do you categorize truck transport versus car 00:24:29.540 --> 00:24:31.070 align:middle line:90% or passenger transport? 00:24:31.070 --> 00:24:33.260 align:middle line:84% We know, in the United States, SUVs 00:24:33.260 --> 00:24:35.060 align:middle line:84% are classified as trucks, which makes 00:24:35.060 --> 00:24:38.030 align:middle line:84% them exempt from previous efficiency standards. 00:24:38.030 --> 00:24:40.520 align:middle line:84% So the point is, as you go across these vertical slices 00:24:40.520 --> 00:24:42.440 align:middle line:84% in this particular Sankey diagram, 00:24:42.440 --> 00:24:45.050 align:middle line:84% you can't always trace all the flows in the same way 00:24:45.050 --> 00:24:47.905 align:middle line:84% that you can in the previous Sankey diagrams we looked at. 00:24:47.905 --> 00:24:50.030 align:middle line:84% You can see that there's a few gaps in between some 00:24:50.030 --> 00:24:53.070 align:middle line:84% of these flows because, where does electricity go? 00:24:53.070 --> 00:24:55.070 align:middle line:84% It goes to a lot of these different systems, not 00:24:55.070 --> 00:24:57.420 align:middle line:84% necessarily just the heating and cooling space. 00:24:57.420 --> 00:24:59.615 align:middle line:84% But it may, let's say, go to industrial uses. 00:24:59.615 --> 00:25:02.538 align:middle line:90% 00:25:02.538 --> 00:25:04.080 align:middle line:84% Having said that, we should also look 00:25:04.080 --> 00:25:06.540 align:middle line:84% at exactly what they're trying to measure in this paper. 00:25:06.540 --> 00:25:07.860 align:middle line:90% They make a very clear-- 00:25:07.860 --> 00:25:10.500 align:middle line:84% well, they make a series of distinctions between exergy, 00:25:10.500 --> 00:25:12.630 align:middle line:90% energy, and entropy. 00:25:12.630 --> 00:25:14.910 align:middle line:84% They quote this Rosen and Dincer paper of 2008 00:25:14.910 --> 00:25:17.130 align:middle line:84% saying that "exergy is a measure of the usefulness 00:25:17.130 --> 00:25:19.890 align:middle line:84% or value or quality of an energy form." 00:25:19.890 --> 00:25:22.080 align:middle line:84% This is "defined using thermodynamic principles 00:25:22.080 --> 00:25:24.090 align:middle line:84% as the maximum amount of work which 00:25:24.090 --> 00:25:27.210 align:middle line:84% can be produced by a system or a flow of matter or energy 00:25:27.210 --> 00:25:29.683 align:middle line:84% as it comes to equilibrium with a reference environment." 00:25:29.683 --> 00:25:32.100 align:middle line:84% And the reason why they make this distinction is because-- 00:25:32.100 --> 00:25:35.130 align:middle line:84% I've said before and also MacKay writes in his book-- 00:25:35.130 --> 00:25:37.050 align:middle line:84% that there's high-grade forms of energy 00:25:37.050 --> 00:25:38.610 align:middle line:90% and low-grade forms of energy. 00:25:38.610 --> 00:25:41.850 align:middle line:84% And the intrinsic distinction between these is entropy. 00:25:41.850 --> 00:25:44.130 align:middle line:84% For example, electricity or mechanical work 00:25:44.130 --> 00:25:47.880 align:middle line:84% is the kind of energy that can be captured quite easily 00:25:47.880 --> 00:25:52.000 align:middle line:84% and recaptured and can also be used for many different things. 00:25:52.000 --> 00:25:53.550 align:middle line:84% But if you try to heat up a space, 00:25:53.550 --> 00:25:55.500 align:middle line:84% once you put heat energy into a room, 00:25:55.500 --> 00:25:57.600 align:middle line:84% it's very hard to recapture that energy. 00:25:57.600 --> 00:26:00.360 align:middle line:84% They make a distinction-- the first electricity 00:26:00.360 --> 00:26:03.300 align:middle line:84% or mechanical work is a high-grade form of energy. 00:26:03.300 --> 00:26:06.390 align:middle line:84% And MacKay calls heat a low-grade form of energy. 00:26:06.390 --> 00:26:08.190 align:middle line:84% They make a distinction here by exergy, 00:26:08.190 --> 00:26:10.920 align:middle line:84% saying exergy is how much output work can 00:26:10.920 --> 00:26:13.710 align:middle line:84% be captured from the maximum theoretical work that 00:26:13.710 --> 00:26:15.530 align:middle line:90% can be captured. 00:26:15.530 --> 00:26:17.810 align:middle line:84% Here's their definition in their papers. 00:26:17.810 --> 00:26:19.370 align:middle line:84% They say exergy efficiency is based 00:26:19.370 --> 00:26:21.500 align:middle line:84% on the first and second law of thermodynamics. 00:26:21.500 --> 00:26:24.042 align:middle line:84% They use it because they want to provide an equitable measure 00:26:24.042 --> 00:26:25.700 align:middle line:90% of conversion efficiency. 00:26:25.700 --> 00:26:27.650 align:middle line:84% They define it as mechanical work 00:26:27.650 --> 00:26:29.870 align:middle line:84% because mechanical work, like electricity, 00:26:29.870 --> 00:26:32.690 align:middle line:84% can be captured and recaptured quite easily. 00:26:32.690 --> 00:26:34.190 align:middle line:84% If you put it into a storage system, 00:26:34.190 --> 00:26:36.780 align:middle line:84% whether or not it's physical or mechanical or chemical, 00:26:36.780 --> 00:26:38.900 align:middle line:84% you can quite often recapture a very large portion 00:26:38.900 --> 00:26:39.770 align:middle line:90% of the energy. 00:26:39.770 --> 00:26:42.020 align:middle line:84% That's not the same thing for a heat battery. 00:26:42.020 --> 00:26:44.900 align:middle line:84% Let's say you put, as I said last week, 00:26:44.900 --> 00:26:47.930 align:middle line:90% heat into a hot water heater. 00:26:47.930 --> 00:26:49.850 align:middle line:84% You can store the energy for a long time, 00:26:49.850 --> 00:26:52.820 align:middle line:84% but it's very hard to take the heat energy out of the water 00:26:52.820 --> 00:26:56.060 align:middle line:84% and recapture it for future use or converting it back to, let's 00:26:56.060 --> 00:26:59.580 align:middle line:90% say, electricity or fuel. 00:26:59.580 --> 00:27:03.320 align:middle line:84% So the reason why we look at this Cullen and Allwood paper-- 00:27:03.320 --> 00:27:05.930 align:middle line:84% this is actually more like a traditional Sankey diagram 00:27:05.930 --> 00:27:07.970 align:middle line:90% because they actually are much-- 00:27:07.970 --> 00:27:09.830 align:middle line:84% they find it easier, I think, in this paper 00:27:09.830 --> 00:27:12.170 align:middle line:84% to measure exactly what the theoretical efficiency 00:27:12.170 --> 00:27:12.860 align:middle line:90% limits are. 00:27:12.860 --> 00:27:15.650 align:middle line:84% They can trace exactly where the energy sources go. 00:27:15.650 --> 00:27:17.930 align:middle line:84% Because they're not going into different services 00:27:17.930 --> 00:27:20.150 align:middle line:84% or different categories of services, 00:27:20.150 --> 00:27:22.670 align:middle line:84% they define things more clearly as going from energy sources 00:27:22.670 --> 00:27:25.340 align:middle line:84% to direct fuel use to conversion devices. 00:27:25.340 --> 00:27:27.590 align:middle line:84% They don't have the same vertical slices 00:27:27.590 --> 00:27:29.038 align:middle line:90% the other diagram does. 00:27:29.038 --> 00:27:30.830 align:middle line:84% And you can see quite clearly in this paper 00:27:30.830 --> 00:27:33.560 align:middle line:84% exactly where our energy goes to. 00:27:33.560 --> 00:27:36.230 align:middle line:90% We start with 475 exajoules. 00:27:36.230 --> 00:27:38.610 align:middle line:84% This is global energy demand in 2005, 00:27:38.610 --> 00:27:41.670 align:middle line:84% and it's probably much higher almost 20 years later. 00:27:41.670 --> 00:27:43.940 align:middle line:84% But the point is that we only get to about 11% 00:27:43.940 --> 00:27:48.140 align:middle line:84% of the total energy is converted into useful energy, namely 00:27:48.140 --> 00:27:52.400 align:middle line:84% in these forms of motion, heat, and cooling, light, and sound. 00:27:52.400 --> 00:27:56.330 align:middle line:84% The other 89%, we lose to combustion, 00:27:56.330 --> 00:27:58.850 align:middle line:84% heat exchange, oxidation, mixing. 00:27:58.850 --> 00:28:01.490 align:middle line:84% As we transfer heat, we lose energy 00:28:01.490 --> 00:28:03.960 align:middle line:84% through heat exchange, exhaust, heat losses, 00:28:03.960 --> 00:28:06.320 align:middle line:84% and electrical resistance in friction and fission. 00:28:06.320 --> 00:28:10.655 align:middle line:84% This is not to say that they say the theoretical limit is 00:28:10.655 --> 00:28:13.670 align:middle line:84% recovering the 89% of energy efficiency or energy 00:28:13.670 --> 00:28:14.630 align:middle line:90% that's lost. 00:28:14.630 --> 00:28:17.510 align:middle line:84% Having said that, we know that we have existing technologies 00:28:17.510 --> 00:28:18.470 align:middle line:90% and systems. 00:28:18.470 --> 00:28:22.220 align:middle line:84% All of these various losses are because of conversion losses. 00:28:22.220 --> 00:28:24.050 align:middle line:84% The technologies we have, the systems 00:28:24.050 --> 00:28:26.870 align:middle line:84% we have convert energy in certain ways 00:28:26.870 --> 00:28:29.870 align:middle line:84% into certain kinds of end uses that we want, 00:28:29.870 --> 00:28:32.570 align:middle line:90% like light and heat and motion. 00:28:32.570 --> 00:28:34.580 align:middle line:84% And all those conversion technologies 00:28:34.580 --> 00:28:35.600 align:middle line:90% may be inefficient. 00:28:35.600 --> 00:28:38.330 align:middle line:84% And what the point of this paper, these two papers, 00:28:38.330 --> 00:28:41.210 align:middle line:84% is that, how theoretically efficient could we be? 00:28:41.210 --> 00:28:43.850 align:middle line:84% They argue that we could be 89% more efficient. 00:28:43.850 --> 00:28:47.180 align:middle line:84% 89% more efficient would reduce our primary energy use 00:28:47.180 --> 00:28:52.490 align:middle line:84% quite a bit and reduce our climate change problems also. 00:28:52.490 --> 00:28:55.970 align:middle line:84% So if you look at how they define energy efficiency, 00:28:55.970 --> 00:28:58.468 align:middle line:84% they have a quality factor and exergy efficiency. 00:28:58.468 --> 00:29:00.260 align:middle line:84% The "e" column to look at it here, I think, 00:29:00.260 --> 00:29:01.860 align:middle line:90% is the right-hand side. 00:29:01.860 --> 00:29:04.160 align:middle line:84% You can look at it exactly how efficient 00:29:04.160 --> 00:29:06.950 align:middle line:90% our various technologies are. 00:29:06.950 --> 00:29:09.080 align:middle line:84% For upstream conversion, you can see 00:29:09.080 --> 00:29:11.090 align:middle line:84% that electricity generation from oil 00:29:11.090 --> 00:29:15.020 align:middle line:84% is relatively efficient, actually, but much less 00:29:15.020 --> 00:29:17.670 align:middle line:84% efficient than fuel transformations, 00:29:17.670 --> 00:29:21.060 align:middle line:84% such as preparing direct fuel use or renewable energy 00:29:21.060 --> 00:29:22.070 align:middle line:90% resources. 00:29:22.070 --> 00:29:25.940 align:middle line:84% You can see that oil, biomass, gas, coal, and nuclear are 00:29:25.940 --> 00:29:28.850 align:middle line:84% much less exergy efficient than renewables or fuel 00:29:28.850 --> 00:29:30.780 align:middle line:90% transformations. 00:29:30.780 --> 00:29:33.060 align:middle line:84% Combined heat and power and heat are also 00:29:33.060 --> 00:29:36.930 align:middle line:84% relatively low in terms of their exergy transformation. 00:29:36.930 --> 00:29:38.400 align:middle line:84% The other thing to notice here is 00:29:38.400 --> 00:29:41.250 align:middle line:84% that this kind of quality factor gets 00:29:41.250 --> 00:29:42.960 align:middle line:84% at the idea of how easily you can 00:29:42.960 --> 00:29:46.320 align:middle line:90% convert the energy to exergy. 00:29:46.320 --> 00:29:49.660 align:middle line:84% And so they put in 100% basically as a plug here. 00:29:49.660 --> 00:29:51.960 align:middle line:84% It basically accounts for, let's say, 00:29:51.960 --> 00:29:54.550 align:middle line:84% fuel losses or transformation losses. 00:29:54.550 --> 00:29:57.750 align:middle line:84% And you can see that nuclear, renewables, and fuel 00:29:57.750 --> 00:30:00.060 align:middle line:84% transformations, such as direct fuel use, 00:30:00.060 --> 00:30:02.370 align:middle line:84% are all relatively efficient, if only 00:30:02.370 --> 00:30:06.690 align:middle line:84% because renewables and nuclear power use electricity. 00:30:06.690 --> 00:30:08.400 align:middle line:84% Electricity is-- relatively little is 00:30:08.400 --> 00:30:10.890 align:middle line:84% lost in terms of transmission compared 00:30:10.890 --> 00:30:12.720 align:middle line:90% to other types of energy. 00:30:12.720 --> 00:30:14.280 align:middle line:84% Fuel transformation is considered 00:30:14.280 --> 00:30:15.905 align:middle line:84% to be relatively efficient because it's 00:30:15.905 --> 00:30:17.760 align:middle line:84% going to be produced as a direct fuel. 00:30:17.760 --> 00:30:19.710 align:middle line:84% This is only measuring the efficiency 00:30:19.710 --> 00:30:22.200 align:middle line:84% of the upstream conversion, not necessarily the end 00:30:22.200 --> 00:30:24.480 align:middle line:84% use down the road, which we'll see 00:30:24.480 --> 00:30:27.840 align:middle line:90% in this next, actually, table. 00:30:27.840 --> 00:30:30.360 align:middle line:84% This table shows the exergy efficiency 00:30:30.360 --> 00:30:32.460 align:middle line:90% of end-use conversion devices. 00:30:32.460 --> 00:30:34.620 align:middle line:84% You can see across the board all of our end 00:30:34.620 --> 00:30:38.670 align:middle line:84% uses for motion, for heat, and for other services are all 00:30:38.670 --> 00:30:39.420 align:middle line:90% relatively low. 00:30:39.420 --> 00:30:43.715 align:middle line:84% All devices convert about 25% of the possible theoretical 00:30:43.715 --> 00:30:44.340 align:middle line:90% maximum exergy. 00:30:44.340 --> 00:30:47.060 align:middle line:90% 00:30:47.060 --> 00:30:48.812 align:middle line:84% And you can see that's true for almost all 00:30:48.812 --> 00:30:50.770 align:middle line:84% of our different technologies-- diesel, petrol, 00:30:50.770 --> 00:30:54.190 align:middle line:84% aircraft engines, oil burners, biomass burners, and so on. 00:30:54.190 --> 00:30:57.190 align:middle line:84% One point I always make to engineers in this class 00:30:57.190 --> 00:31:00.340 align:middle line:84% is that, if you look at these two tables and the Sankey 00:31:00.340 --> 00:31:02.890 align:middle line:84% diagrams, if you're working with these technologies, 00:31:02.890 --> 00:31:04.840 align:middle line:84% that should hopefully be motivating 00:31:04.840 --> 00:31:08.710 align:middle line:84% because you improve one of these technologies a little bit-- 00:31:08.710 --> 00:31:11.650 align:middle line:84% if that technology can be scaled and adopted widely, 00:31:11.650 --> 00:31:14.620 align:middle line:84% that can have a huge impact on our total use, 00:31:14.620 --> 00:31:15.670 align:middle line:90% efficient use of energy. 00:31:15.670 --> 00:31:18.500 align:middle line:90% 00:31:18.500 --> 00:31:20.900 align:middle line:84% If we look at the compound efficiency, 00:31:20.900 --> 00:31:22.840 align:middle line:84% which takes into account fuel transformation, 00:31:22.840 --> 00:31:26.500 align:middle line:84% electricity generation, and end-use device conversion. 00:31:26.500 --> 00:31:29.650 align:middle line:84% Again, for some, actually, these-- 00:31:29.650 --> 00:31:32.470 align:middle line:84% electricity generation does not factor into what the aircraft 00:31:32.470 --> 00:31:34.840 align:middle line:90% engines or coal burners. 00:31:34.840 --> 00:31:36.662 align:middle line:90% They put 100% of the plug here. 00:31:36.662 --> 00:31:38.620 align:middle line:84% But the key point is you multiply these factors 00:31:38.620 --> 00:31:40.900 align:middle line:84% together, and you get a compound efficiency. 00:31:40.900 --> 00:31:44.230 align:middle line:84% So we started out with a very efficient fuel transformation 00:31:44.230 --> 00:31:46.330 align:middle line:84% in direct fuel use, as in aircraft engines, 00:31:46.330 --> 00:31:49.000 align:middle line:84% diesel engines, and petrol engines. 00:31:49.000 --> 00:31:51.340 align:middle line:84% But then we exhaust a lot of the energy 00:31:51.340 --> 00:31:55.490 align:middle line:84% out because we have to burn the fuel directly. 00:31:55.490 --> 00:31:57.080 align:middle line:84% A lot of heat goes out the tailpipe 00:31:57.080 --> 00:31:58.370 align:middle line:90% or the back of the engine. 00:31:58.370 --> 00:32:00.680 align:middle line:84% So we actually get fairly low compound efficiencies. 00:32:00.680 --> 00:32:02.930 align:middle line:84% Again, across all the conversion devices 00:32:02.930 --> 00:32:04.940 align:middle line:84% where we get final services, you can 00:32:04.940 --> 00:32:07.440 align:middle line:84% see that the overall average is quite low. 00:32:07.440 --> 00:32:12.230 align:middle line:84% We have overall average of 11% of actual final energy 00:32:12.230 --> 00:32:15.710 align:middle line:84% use or final services from the original primary energy 00:32:15.710 --> 00:32:17.350 align:middle line:90% going in. 00:32:17.350 --> 00:32:19.310 align:middle line:84% And so we can take this thinking further. 00:32:19.310 --> 00:32:22.220 align:middle line:84% This is the report by Griffith et al. 00:32:22.220 --> 00:32:23.740 align:middle line:90% It's called "Rewiring America"-- 00:32:23.740 --> 00:32:26.200 align:middle line:84% argues that we can have basically a highly electrified, 00:32:26.200 --> 00:32:29.020 align:middle line:84% decarbonized US energy sector, basically providing 00:32:29.020 --> 00:32:31.840 align:middle line:84% all the same services that the US economy currently 00:32:31.840 --> 00:32:35.440 align:middle line:84% provides, and argues that we have massive efficiencies 00:32:35.440 --> 00:32:36.250 align:middle line:90% in electrification. 00:32:36.250 --> 00:32:39.190 align:middle line:84% They actually trace all the energy use through 00:32:39.190 --> 00:32:42.430 align:middle line:84% all the US government reports they can find. 00:32:42.430 --> 00:32:45.310 align:middle line:84% They identify places where some of the Sankey 00:32:45.310 --> 00:32:48.610 align:middle line:84% diagram they find either misleading or duplicative 00:32:48.610 --> 00:32:50.470 align:middle line:84% because we're actually using fossil fuels. 00:32:50.470 --> 00:32:53.770 align:middle line:84% They argue that there's some large portion-- about 8% 00:32:53.770 --> 00:32:56.380 align:middle line:84% of the energy economy is misleading accounting 00:32:56.380 --> 00:32:58.150 align:middle line:90% of existing primary energy. 00:32:58.150 --> 00:33:01.630 align:middle line:84% If we eliminate fossil fuels, we'll get rid of this 8%. 00:33:01.630 --> 00:33:05.420 align:middle line:84% If we have current losses in residential, commercial, 00:33:05.420 --> 00:33:08.740 align:middle line:84% and in the industrial sector because we use fossil fuels, 00:33:08.740 --> 00:33:10.420 align:middle line:84% if we electrify these things, they'll 00:33:10.420 --> 00:33:15.010 align:middle line:84% eliminate another-- it looks like about 15% or 16% 00:33:15.010 --> 00:33:16.150 align:middle line:90% of energy use. 00:33:16.150 --> 00:33:19.762 align:middle line:84% If you electrify vehicles, they eliminate 10% electricity use. 00:33:19.762 --> 00:33:21.220 align:middle line:84% And you can see what they're trying 00:33:21.220 --> 00:33:24.550 align:middle line:84% to do is they're getting from the 97 or so quads, 00:33:24.550 --> 00:33:26.608 align:middle line:90% the US [INAUDIBLE] 100 quads. 00:33:26.608 --> 00:33:28.900 align:middle line:84% And they're trying to increase the percentage of energy 00:33:28.900 --> 00:33:33.670 align:middle line:84% services at the end, energy services increasing to 27%, 00:33:33.670 --> 00:33:35.590 align:middle line:84% and trying to get rid of what they call, 00:33:35.590 --> 00:33:37.053 align:middle line:90% with quotes, "waste." 00:33:37.053 --> 00:33:38.470 align:middle line:84% They argue that some of this waste 00:33:38.470 --> 00:33:40.960 align:middle line:84% can be captured through electrification. 00:33:40.960 --> 00:33:43.985 align:middle line:84% They also do this in a Super Sankey diagram. 00:33:43.985 --> 00:33:45.610 align:middle line:84% I encourage you to go to the PDF if you 00:33:45.610 --> 00:33:47.400 align:middle line:90% click on this interactive link. 00:33:47.400 --> 00:33:49.780 align:middle line:84% What's quite useful about this interactive diagram is 00:33:49.780 --> 00:33:51.670 align:middle line:84% you can click on any of the final services 00:33:51.670 --> 00:33:54.670 align:middle line:84% we desire, and it'll show you where all the energy comes 00:33:54.670 --> 00:33:58.780 align:middle line:90% from in its history or path. 00:33:58.780 --> 00:34:00.460 align:middle line:84% The reason why this is really useful 00:34:00.460 --> 00:34:02.320 align:middle line:84% is, if you think about efficiency, 00:34:02.320 --> 00:34:04.600 align:middle line:84% we have a set of final services here 00:34:04.600 --> 00:34:06.320 align:middle line:90% that we demand at the right. 00:34:06.320 --> 00:34:09.550 align:middle line:84% We have a set of primary energy sources going in on the left. 00:34:09.550 --> 00:34:13.639 align:middle line:84% If you can reduce consumption on this right-hand side, 00:34:13.639 --> 00:34:16.150 align:middle line:84% you eliminate all the upstream [INAUDIBLE] from happening. 00:34:16.150 --> 00:34:19.780 align:middle line:84% And, crucially, you eliminate all the previous inefficiencies 00:34:19.780 --> 00:34:20.449 align:middle line:90% or losses. 00:34:20.449 --> 00:34:22.239 align:middle line:84% In other words, if you reduce consumption, 00:34:22.239 --> 00:34:24.400 align:middle line:84% let's say, 1% here, you are going 00:34:24.400 --> 00:34:28.210 align:middle line:84% to reduce much more than 1% of primary energy use on the left 00:34:28.210 --> 00:34:31.570 align:middle line:84% because all the efficiency gained by simply not demanding 00:34:31.570 --> 00:34:33.250 align:middle line:90% the final service in the end. 00:34:33.250 --> 00:34:36.350 align:middle line:84% So this is, again, why we focus on consumption in class. 00:34:36.350 --> 00:34:39.130 align:middle line:84% I want you to think of efficiency as percolating 00:34:39.130 --> 00:34:40.389 align:middle line:90% through the whole system. 00:34:40.389 --> 00:34:43.120 align:middle line:84% If we reduce our consumption or demand, 00:34:43.120 --> 00:34:46.510 align:middle line:84% how much efficiency does it lead to upstream? 00:34:46.510 --> 00:34:49.690 align:middle line:84% And this brings me back just to this set of final services. 00:34:49.690 --> 00:34:53.710 align:middle line:84% We desire passenger transport, freight transport, structures, 00:34:53.710 --> 00:34:56.500 align:middle line:84% sustenance, like food, hygiene, and thermal comfort, 00:34:56.500 --> 00:34:58.173 align:middle line:90% communication, illumination. 00:34:58.173 --> 00:34:59.590 align:middle line:84% What I want you to think about is, 00:34:59.590 --> 00:35:01.450 align:middle line:84% if we make these things more efficient 00:35:01.450 --> 00:35:04.780 align:middle line:84% either in our conversion devices or in our demand or use 00:35:04.780 --> 00:35:05.720 align:middle line:90% of them-- 00:35:05.720 --> 00:35:07.450 align:middle line:84% for example, we know about a third 00:35:07.450 --> 00:35:10.270 align:middle line:84% of all food in developed countries is thrown away. 00:35:10.270 --> 00:35:12.610 align:middle line:84% If we were to reduce our demand for food 00:35:12.610 --> 00:35:15.160 align:middle line:84% by being less wasteful, how much would we 00:35:15.160 --> 00:35:19.330 align:middle line:84% reduce upstream both in terms of our vehicles, factories, 00:35:19.330 --> 00:35:23.080 align:middle line:84% and buildings, but, ultimately, the direct fuel use and motion 00:35:23.080 --> 00:35:25.360 align:middle line:84% that actually went into producing a third of food that 00:35:25.360 --> 00:35:26.420 align:middle line:90% is wasted? 00:35:26.420 --> 00:35:29.380 align:middle line:84% We also know that we could have different demands 00:35:29.380 --> 00:35:30.640 align:middle line:90% for thermal comfort. 00:35:30.640 --> 00:35:33.830 align:middle line:84% Based on the calculation we did in class last week, 00:35:33.830 --> 00:35:37.190 align:middle line:84% if we simply wore a sweater or simply lowered 00:35:37.190 --> 00:35:39.020 align:middle line:84% the degree on our thermostats by 1-- 00:35:39.020 --> 00:35:40.792 align:middle line:84% lower our thermostats by 1 degree, 00:35:40.792 --> 00:35:43.250 align:middle line:84% we know that we would actually reduce quite a bit of energy 00:35:43.250 --> 00:35:45.710 align:middle line:84% use that goes into thermal comfort, one of the largest 00:35:45.710 --> 00:35:47.800 align:middle line:90% categories of energy use. 00:35:47.800 --> 00:35:51.060 align:middle line:84% So what we're going to think through in class on Thursday 00:35:51.060 --> 00:35:53.590 align:middle line:84% is I want you to think of yourself as a member of Team 00:35:53.590 --> 00:35:55.740 align:middle line:90% Heat or Motion or Other. 00:35:55.740 --> 00:35:58.240 align:middle line:84% And we're going to ask ourselves these questions in groups-- 00:35:58.240 --> 00:36:00.032 align:middle line:84% how much energy or greenhouse gas emissions 00:36:00.032 --> 00:36:02.950 align:middle line:84% could theoretically be saved for your team? 00:36:02.950 --> 00:36:05.523 align:middle line:84% Which single technology improvement for your team-- 00:36:05.523 --> 00:36:07.690 align:middle line:84% this can be a technology in terms of fuel conversion 00:36:07.690 --> 00:36:10.000 align:middle line:84% or electricity generation or end-use conversion-- 00:36:10.000 --> 00:36:12.040 align:middle line:84% would achieve the greatest production of energy 00:36:12.040 --> 00:36:13.940 align:middle line:90% and greenhouse gas emissions? 00:36:13.940 --> 00:36:15.940 align:middle line:84% What reduction of primary energy could your team 00:36:15.940 --> 00:36:19.600 align:middle line:84% achieve with a 20% reduction in final services? 00:36:19.600 --> 00:36:23.440 align:middle line:84% How could you achieve a 50% reduction in primary energy? 00:36:23.440 --> 00:36:27.010 align:middle line:84% And which technology would you not try to improve? 00:36:27.010 --> 00:36:27.760 align:middle line:90% Or why? 00:36:27.760 --> 00:36:29.980 align:middle line:84% I'd just like you to think through these whole chains 00:36:29.980 --> 00:36:32.770 align:middle line:84% of technologies, systems, and demands. 00:36:32.770 --> 00:36:36.420 align:middle line:84% Thank you very much, and I'll see you in class soon. 00:36:36.420 --> 00:36:48.000 align:middle line:90%