I hope you've enjoyed our journey into the world of Sankey diagrams. They are a powerful tool to summarize a lot of information in one place. They illustrate the dynamism and complexity of energy systems, and they show the various forms of energy we use to provide energy services. They highlight the tremendous challenges associated with rejected or wasted energy and point to the huge opportunity for innovation in energy efficiency. They show macro-level changes over time in our energy sources, like the ongoing decrease in coal reliance in the US and the increasing use of renewables. They are a great comparative tool to see regional differences in fuel sources. Their biggest benefit is how they illustrate the complex interconnection of energy fuels with major areas of energy use. But cool as they are, Sankey diagrams do not show everything. To me, the biggest element missing in Sankey diagrams is people. These diagrams don't show the people who mine or extract our energy resources. They don't show the companies that produce and transport fuels and materials. They don't show the policymakers deciding whether or not to grant a permit for a new pipeline, or economists debating over what market mechanisms to put in place to incentivize carbon emission reductions. They don't show the apartment renters who have to open their windows in the winter because they can't control the heat in their homes, or the families using ovens to heat their homes when they lose power. They don't show the health impacts associated with extracting and processing metals and minerals that are essential for new technologies like solar panels and batteries. They don't show the air pollution associated with urban transportation infrastructure. They don't show the mountain top removal associated with some coal mines or the cultural and economic impact that resource extraction and depletion can have on local communities. If we treat the Sankey diagram as a standalone tool, we wind up focusing primarily on the technological, physical dimension of energy systems, and we can overlook the human dimensions. We may discount the importance of human behavior. We may fail to notice a myriad of impacts of energy flows on daily lives. Under those conditions, we run the risk of perpetuating or even aggravating ways that those systems benefit some people and communities to the detriment of others. How can we improve on the foundation that the Sankey diagram provides? We can ask questions. We can build on the Sankey diagram as a foundation. When we look at the energy sources on the left, remember that this part of the diagram represents the capture and production of energy, so that includes drilling for oil and gas, mining for coal, and the metals and minerals used to manufacture solar panels and wind turbines, and the refining processes necessary to turn the raw materials into useable fuels and equipment. It also includes power generation facilities run with fossil fuels, with nuclear energy, and with solar, wind, geothermal, and hydro-power. In the middle, we think about the pipelines, the cargo ships, the railways, and the trucks that move our fuels around. About electricity transmission and distribution wires, about electrical substations, about gas stations, and the like. Then finally towards the right we think about the infrastructure in which we use energy: houses, businesses, industrial and manufacturing facilities, and our transportation networks. Using this physical infrastructure systems view as a foundation we can start to ask questions to bring the human and social dimensions into focus. Who owns the facilities and infrastructure? Where do the profits go? Who works at the facilities? Who lives nearby? What are the environmental impacts of the facilities? What are their health effects? Whose health is impacted? How much do the services cost? Who has access to the services? Who gets discounts? Why were the facilities sited there? What is the history of those places? What jobs do the facilities create? What stories do people tell about them? What art do they make? What regulations govern the facilities, the infrastructure, and the consumption? Who was involved in the policy processes? How do the policy processes work? These questions start to get at what energy infrastructure means for the people who interact with it, live near it, and ultimately use what it produces, and they train our focus on areas where there are differential impacts on different groups of people, like the increased health burden born by people who live near our energy facilities, and the regulatory and policy processes that include the voices of some, but not all stakeholders. A great way to organize questions like these is the speed framework developed by my director, Professor Elizabeth Wilson and her colleagues Jenny Stevens and Tyler Ray Peterson. This framework identifies six major areas to use when analyzing energy as a socio-technical system: technical, economic, political, regulatory and legal, environmental, and cultural. In my view, the technical category is covered in what's represented by the Sankey diagram at the foundation. Then we can see how the questions fall into the buckets from the speed framework, economic questions like who gets what kind of job, and how energy service prices are determined. Political questions like why facilities wound up where they did and what the process of developing policy entails. Regulatory and legal questions like what are the rules that companies and utilities must follow for building and running facilities and for how energy markets work. Environmental questions about ways that energy infrastructure impacts air, soil, and water, and the health effects of pollution and waste associated with that Infrastructure. Finally, questions about the relationship between energy and culture, how community life is shaped by energy facilities, and how our energy infrastructure becomes a feature in our histories and in the literature, movies, and other forms of artistic expression that make up our social fabric. Going forward, when you think about or hear the term energy systems, I hope what comes to mind is a system that is complex, not only in its physical and technological dimensions but in its human and cultural dimensions as well. When we layer the social life of energy on top of the physical energy system, it becomes easier to identify places where things aren't fair. That gives us the starting point we need to assess systematically where social and justice issues come up and what needs to be fixed.