By Emmanuel Mattey

A Sankey chart/visualization is the type that provides an overview of the flows in a system, such as movements, cost, energy or materials, or in advertising, the customer journey. Elements within the chart are represented with rectangles and texts from a source with links represented by arrows or arcs that have a width proportional to the importance of the flow to a corresponding destination.

The National Academies of Sciences, Engineering and Medicine displayed Our Energy System using a Sankey chart/visualization which gives simply but detailed information on the energy sources/generation and the respective entities that use the energy in proportions and the overall useful and unused energy.

The site initially gives an overview of the energy situation and the respective end-users who make up the total. It also has tabs that lead to other important sources for more information on the subject as shown in the image below.

By clicking on the “start the flow” button, it displayed the chart with the sources of energy through to the respective users and the overall usage. The chart did not make much sense to me when it first opened but upon careful study and navigation, I got the concept and how it depicts the information therein. At the click of every button comes a pop-up containing (shown in the images below) information that gives the audience a better understanding of the concept/chart.

A Sankey chart/visualization is a great way of displaying information in a flow format. However, it does not readily make sense until carefully studied due to the complex look/nature with arrows/arcs crossing. It is therefore advisable to not over-clutter the figure and if possible ignore all weak connections.