Sankey diagram

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Example of a Sankey diagram.
Sankey's original 1898 diagram showing energy efficiency of a steam engine.
Minard's classic diagram of Napoleon's invasion of Russia, using the feature now named after Sankey.

Sankey diagrams are a specific type of flow diagram, in which the width of the arrows is shown proportionally to the flow quantity. They are typically used to visualize energy or material or cost transfers between processes.

Application[edit]

They are also commonly used to visualize the energy accounts or material flow accounts on a regional or national level. Sankey diagrams put a visual emphasis on the major transfers or flows within a system. They are helpful in locating dominant contributions to an overall flow. Often, Sankey diagrams show conserved quantities within defined system boundaries.

Historical Examples[edit]

Sankey diagrams are named after Irish Captain Matthew Henry Phineas Riall Sankey, who used this type of diagram in 1898 in a classic figure (see panel on right) showing the energy efficiency of a steam engine. While the first charts in black and white were merely used to display one type of flow (e.g. steam), using colors for different types of flows has added more degrees of freedom to Sankey diagrams.

One of the most famous Sankey diagrams is Charles Minard's Map of Napoleon's Russian Campaign of 1812. It is a flow map, overlaying a Sankey diagram onto a geographical map. It was created in 1869, so it actually predates Sankey's 'first' Sankey diagram of 1898.

Active Examples[edit]

The United States Energy Information Agency (EIA) produces numerous Sankey diagrams annually in the Annual Energy Report which illustrate the production and consumption of various forms of energy. The report for year 2012 include the following diagrams: Energy Flow, Petroleum Flow, Natural Gas Flow, Electricity Flow, and Coal Flow.

The International Energy Agency (IEA) created an interactive Sankey web application that details the flow of energy for the entire earth. Users can select specific countries, points of time back to 1973, and modify the arrangement of various flows within the Sankey diagram.

The US Department of Energy's Lawrence Livermore Laboratory maintains a site of Sankey diagrams, including US energy flow and carbon flow.

Ben Schmidt, an Assistant Professor of History at Northeastern University, created a Sankey diagram relating majors in college to eventual careers.

See also[edit]

More Energy input means less energy wasted

References[edit]

External links[edit]