Flow Power-Up: Unveiling the Magic of Sankey Charts

Introduction

Sankey charts, also known as stream graphs or Sankey diagrams, are a type of flow diagram that display the quantities of materials, energy, or costs between different processes or entities. They have been used since the 19th century to provide an insightful analysis of processes and help visualize complex systems. This article delves into the creation and applications of Sankey charts, showcasing their unique capabilities to “power up” understanding.

What are Sankey Charts?

Sankey diagrams were originally developed in the late 19th century by British engineer William Playfair. The concept gained popularity in the 20th century, especially in process engineering, and they are now widely used across various fields, including energy, economics, and environmental science.

In a Sankey chart, the width of each arrow is proportional to the magnitude of the flow of material, energy, or cost. This allows for a visual representation of how resources are distributed among different stages of a process. The chart usually starts with an input and terminates with an output, illustrating the direction of the flow or the work performed.

Elements of a Sankey Chart

1. Flow Lines: These lines represent the mass, energy, or material flowing from one process to another. The thickness of the flow lines denotes the amount of material, energy, or cost being transferred or used.

2. Processes: Boxes or shapes that define individual stages of a process. Each process is connected to other processes with flow lines.

3. Nodes: Points where two processes are connected. The nodes denote the points where there is a conversion of materials or energy, such as a chemical reaction or a mechanical work.

Creating Sankey Charts

Sankey charts can be created visually or programmatically through software and programming libraries. Here are some methods to create Sankey charts:

Through Software

• Excel: Add-ins like “Flow Sankey” and “Sankey Chart Creator” can be used to generate Sankey charts in Excel.
• Tableau: Tableau supports creating Sankey charts through its software, which also provides functionality to calculate flows and customize the diagram layout.
• Google Sheets: By using the built-in chart feature, you can create basic Sankey charts with minimal effort.

Through Programming

• Python: Libraries such as matplotlib, plotly, and sankeydiagram help in creating Sankey charts programmatically.
• JavaScript: JavaScript libraries such as Sankey.js can be used to create Sankey diagrams directly in a web browser.

Applications of Sankey Charts

1. Energy Analysis: Display energy flows and losses in power plants, renewable energy systems, and building energy use.

2. Economic Studies: Track how money is distributed between different sectors of the economy or the flow of money in a specific project.

3. Environmental Impact: Visualize the carbon emissions by sector or the composition of waste streams in manufacturing and processing industries.

4. Transportation and Logistics: Model traffic flow, the distribution of public transport passengers, or the flow of goods in supply chain management.

5. Data Science and Big Data: Illustrate the flow of data or the relationships between different variables, especially in machine learning and data visualization projects.

Conclusion

Sankey charts have a unique power-up effect on data visualization, turning complex and voluminous flows of information into intuitively understandable diagrams. With their flexibility in representing flow distributions, these charts offer an invaluable tool for decision-makers, researchers, and enthusiasts alike. Embracing the magic of Sankey charts can lead to smarter, more efficient, and more environmentally sustainable choices in our daily lives and professional endeavors.

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