Define Sankey Diagram.

A Sankey diagram is a visual representation of the flow of energy, material, or resources within a system, process, or network. It provides a graphical depiction of the input, output, and transformation of energy or material flows, allowing for a clear understanding of resource usage, efficiency, and losses. Sankey diagrams are widely used in various fields, including engineering, environmental science, economics, and sustainability analysis, to analyze and communicate complex systems and processes.

Key features of a Sankey diagram include:

1. Flow Direction and Width: Sankey diagrams consist of arrows or lines representing the flow of energy or material between different components or stages of a system. The width of each arrow is proportional to the quantity of energy or material flowing through that particular pathway, providing a visual indication of the relative magnitude of flows.

2. Nodes and Branches: Nodes represent points of input, output, or transformation within the system, such as energy sources, processes, equipment, or end uses. Arrows connect nodes to illustrate the direction and magnitude of flow between them. Branches or pathways may split or merge to show how energy or material is distributed or combined at different stages of the process.

3. Labels and Annotations: Labels and annotations provide additional information about the components, flows, and quantities depicted in the Sankey diagram. They may include descriptions, values, units, percentages, or other relevant details to aid interpretation and analysis.

4. Color Coding and Categories: Color coding can be used to distinguish between different categories or types of flows within the Sankey diagram, such as energy sources, conversion processes, end uses, or waste streams. Color coding enhances clarity and helps identify patterns, trends, and anomalies in the data.

5. Quantitative Analysis: Sankey diagrams allow for quantitative analysis of energy or material flows, including calculations of input-output balances, efficiency ratios, losses, and resource utilization. By visually comparing the widths of arrows and nodes, analysts can assess the distribution, allocation, and efficiency of resources within the system.

Sankey diagrams are valuable tools for decision-making, planning, optimization, and communication in various applications, including energy management, process engineering, environmental impact assessment, and policy analysis. They enable stakeholders to visualize complex systems, identify opportunities for improvement, and communicate findings effectively to diverse audiences.

In summary, a Sankey diagram is a powerful visualization tool that provides insights into the flow and transformation of energy or material within a system, facilitating analysis, optimization, and decision-making in diverse fields.