Vis Comput DOI 10.1007/s00371-015-1186-8 ORIGINAL ARTICLE EnergyViz: an interactive system for visualization of energy systems Haleh Alemasoom1 · Faramarz Samavati1 · John Brosz2 · David Layzell3 © Springer-Verlag Berlin Heidelberg 2015 Abstract Energy systems are under pressure to transform Keywords Energy system · Visualization · Flow · Sankey to address concerns about climate change. The modeling and diagram · Time-varying · Spatial · Animation visualization of energy systems can play an important role in communicating the costs, benefits and trade-offs of energy systems choices. We introduce EnergyViz, a visualization 1 Introduction system that provides an interface for exploring time-varying, multi-attribute and spatial properties of a particular energy The energy systems of developed nations have fueled a very system. EnergyViz integrates several visualization tech- high quality of life, delivering luxuries that would be the envy niques to facilitate exploration of a particular energy system. of all previous generations. Such systems include all stages These techniques include flow diagram representation to in energy flow from its recovery from nature, through the cre- show energy flow, 3D interaction with flow diagrams for ation of energy currencies (gasoline, electricity, etc.) to the expanding viewable data attributes such as emissions and delivery of energy services to meet societal demand. Today an interactive map integrated with flow diagrams for simul- the global scale of climate changing greenhouse gas (GHG) taneous exploration of spatial and abstract information. We and its frightening environmental and economic implications also perform level-of-detail exploration on flow diagrams and have focused attention on the need to transform our energy use smooth animation across the visualizations to represent systems. Developing policies and investment strategies to time-varying data. Finally, we include evaluation results of make energy systems more sustainable requires an under- EnergyViz collected from expert and inexperienced partici- standing of the nature of our existing energy systems. pants. Sankey diagrams are a type of flow diagram that are com- monly used to show the magnitude of energy flows from resources, through commodities to services (see International B Haleh Alemasoom Energy Agency’s website [16] for an example of a Sankey [email protected] diagram). These diagrams provide a top-down perspective Faramarz Samavati on energy systems and make it possible to identify major [email protected] features, inconsistencies or questionable aspects of the data John Brosz that require closer and critical analysis. [email protected] Despite the usefulness of Sankey diagrams, the structure David Layzell of an energy system can be too complex to be fully captured in [email protected] a single diagram. Complex systems typically require several 1 Department of Computer Science, University of Calgary, visualization techniques applied together to show all proper- Calgary, Canada ties of data. 2 Libraries and Cultural Resources, University of Calgary, Energy systems data consist of spatial, time-varying Calgary, Canada and multi-attribute features as well as flow information 3 Canadian Energy Systems Analysis Research (CESAR) that requires advanced visualizations to capture all of this Institute, Calgary, Canada information. In this paper, we introduce a system for visu- 123 H. Alemasoom et al. Fig. 1 An overview of EnergyViz alization of Canada’s energy system which handles the system dataset in Sects. 6, 7, 8 and 9. Evaluation results are complexity of data using linked visualizations (Fig. 1). The presented in Sect. 11, and a discussion of results follows in main component of EnergyViz is interactive Sankey dia- Sect. 12. This paper ends in Sect. 13 with conclusion and grams. To address the complexity of the energy systems, ideas for future work. we support level-of-detail exploration of Sankey diagrams using a hierarchical structure for data. We also take advan- tage of an interactive map to show spatial information 2 Energy system background and explore regional Sankey diagrams. To support view- ing GHG emissions, we display them as simple bar charts Energy systems encompass the generation and conversion perpendicular to the Sankey diagram’s plane. To illustrate technologies as well as the distribution network which pro- the relationship between these attributes and conventional vides energy services (mobility, light, nutrition, industrial Sankey, we use smooth animation to change the view. products, etc.) from the energy sources that nature provides. Smooth animation is also used for other aspects of our Examples of energy sources include fossil fuels (coal, oil and visualization system including the visualization of tem- gas), uranium and renewables (hydropower, biomass, wind, poral changes and increasing or decreasing the level of solar). These energy sources are converted into commodities detail. or currencies (e.g., gasoline, diesel, electricity, wood pellets, EnergyViz, is created using techniques discussed in our etc.) that can be moved to where the energy is needed to be previous paper [3]. In [3], we discuss how Sankey dia- converted into a service. grams are generated and smoothly animated. In this paper, In this paper, we use data from the Canadian Energy Sys- we improve the layout of a Sankey diagrams and their tems Simulation (CanESS) model [9]. CanESS draws on animation using optimization. We also provide evalua- historical data from a range of government sources and cre- tion results of EnergyViz. This evaluation is performed ates an integrated model of energy flows and GHG emissions using a qualitative study of both expert and inexperienced by Canadian province for the period 1978–2010. This histor- participants. ical model is then used to project the future of Canadian The remainder of this paper is organized as follows. Sec- energy system based on assumptions about population and tion 2 presents a background on Energy system and tasks GDP growth, energy sources, conversion technologies and based on which we designed our system. Related work fol- service demand. lows in Sect. 4. We discuss data abstraction in Sect. 5.We Some of the elements that form energy systems are the describe our design choices for different aspects of energy energy flow inside a region, production levels for energy 123 EnergyViz: an interactive system for visualization of energy systems sources, trade of energy across regions and also other show progression of an event. Another example system which attributes such as amount of green house gas (GHG) emis- uses parallel sets [5] technique to show people’s movement sions produced throughout the process of energy generation information from one group to another is the work done to delivery. We use such historical data for Canada provided by von Landesberger et al. [27]. In their approach, paral- by CanESS in our visualization. lel sets are used to show change in classes of data over time. Furthermore, several works focus visualization of flow 3 Motivation and tasks on a map. Phan et al. [11] initially introduced techniques for visualizing flows on a map (flow map) and presented Our project was motivated by the need of our energy system algorithms for optimizing layout of flow maps and reduc- expert collaborators for sophisticated visualizations that can ing visual clutter. In EnergyViz, we use a basic flow map be used both by the public and by policy makers to understand representation to show energy imports and exports on a the features of Canada’s energy system. map. While Sankey diagrams have been widely used in visualiz- ing energy systems, they can be criticized in different ways. A Time-varying data visualization There is a vast literature Sankey diagram is often too complex particularly when pop- on visualization of time-varying data [2,18]. Various tech- ulated with highly detailed information, making it difficult niques to visualize time focus on either static representation to see important aspects of the energy system being repre- of all time steps in 2D or 3D space or dynamic visualiza- sented. Besides, other important information such as GHG tion using animation [1]. Small multiples [26] is a technique emissions cannot be simply added to a Sankey diagram as it which puts together different variations of a single visualiza- increases its visual complexity. tion distinguished by time or other features. This technique, In summary, based on discussions we had with our col- however, limits the number of viewable time steps due to laborators, we aim at achieving the following goals using lack of screen space. Kothur et al. [17] suggest a clustering EnergyViz: technique to reduce the number of maps required to represent data. 1. Being able to show temporal changes in Canada’s energy Animation is also used as a common technique to show system. This feature is particularly important when want- temporal changes. Arguments exist around effectiveness of ing to compare historical differences among regions, or animation to visualize trends [22,23]; however, animation alternative energy futures. Such insights are particularly has proved successful for presentation and viewing results of valuable for decision makers as they consider different analysis [1,23]. Gapminder [13] is an example of a successful policies and investment strategies; use of animation in information visualization. 2. Reducing visual complexity of Sankey diagrams by view- Several previous work discuss creating