Visualizing Efficiency: How Sankey Charts Unveil the Flow of Energy and Resources

In the ever-evolving landscape of data visualization, Sankey diagrams stand out as powerful tools for depicting the flow of various quantities. Originally introduced in 1898 by Sankey, an engineer involved in steam engine efficiency studies, these charts are now extensively used in a wide array of fields to visualize energy, resources, data transfers, and the life cycle of manufactured products. They offer a clear, intuitive way to understand the intricate flow of materials, inputs, outputs, and associated efficiency losses or gains. This article delves into the creation of Sankey diagrams, their applications, and the insights they provide into the efficient use of energy and resources.

Understanding Sankey Diagrams

A Sankey diagram is a flow diagram that uses the widths of the arrows or bridges to visually represent the quantities of a system’s flows or transitions. The diagram starts with inputs (sources) and shows how these inputs are transformed or lost as they are processed through a system. The outputs of the system are then shown, and any losses incurred in the process are also highlighted. The horizontal position of the flows represents the process or stage of the transformation, and the width of the flow represents the quantity or volume of energy or resources being transferred or consumed.

Creating a Sankey Diagram

Data Collection: The first step in creating a Sankey diagram is gathering and processing the data that will be represented. This typically involves quantities of input and output flows, as well as any losses or gains within the system.
Organization: Data must be organized into relevant categories or stages. For example, in energy efficiency analysis, the sources of energy (e.g., coal, solar, wind), the processes of energy production (e.g., electricity generation, heating, cooling), and the final consumption of energy (e.g., lighting, cooking, transportation) can be organized into stages.
Visualization Software: There are several software and programming languages available for creating Sankey diagrams. These include Microsoft Excel, R (particularly using the ggplot2 and ggforce packages), Python (with libraries such as matplotlib, seaborn, or plotly), and dedicated Sankey diagram creation tools like Displayr or Tableau.
Designing the Diagram: Once your data is organized, it’s time to design the layout of your Sankey diagram. Consider the order of inputs and outputs to align visually with the process flow, and ensure that the color coding for each flow makes sense in the context of the data and analysis. The width of each flow should correspond to the quantity or volume of the flow.
Finalization: Make sure the labels are clear and concise, and that the diagram is readable. After finalizing the design, the Sankey diagram effectively communicates the flow of energy or resources in a system, highlighting key insights such as the efficiency losses, overall resource use, and potential areas for optimization.

Applications of Sankey Diagrams

Sankey diagrams are incredibly versatile and can be applied across various domains:

Energy Analysis: They are commonly used to analyze the energy flow in buildings or entire power systems, revealing energy sources, energy uses, and efficiency losses.
Material Flow Analysis: In manufacturing and supply chain analysis, Sankey diagrams help visualize the flow and transformation of materials and products from raw materials to the final product.
Life Cycle Assessment: They can be used to depict the inputs and outputs of a product or service across its entire life cycle, including raw material extraction, production, use, and disposal.
Data Science and Big Data: In big data projects, Sankey diagrams can help illustrate the flow of data through various processes, such as data collection, cleaning, analysis, and reporting.

Conclusion

Sankey diagrams are a powerful and visually appealing tool for understanding the flow of energy and resources. Their ability to depict not only the total amount of flow but also the distribution of outputs from inputs offers a clear, comparative look at a system. By using them, decision-makers can gain insights into the efficiency of processes, identify areas for improvement, and make informed decisions to achieve greater efficiency and sustainability goals. As data visualization continues to evolve, Sankey diagrams remain a key tool in the arsenal for anyone seeking to make sense of the complex flow of energy and resources in modern systems.

SankeyMaster

SankeyMaster is your go-to tool for creating complex Sankey charts . Easily enter data and create Sankey charts that accurately reveal intricate data relationships.