A different power Sankey diagram…

Kevin Deegan-Krause, an Associate Professor of Political Science at Wayne State University has contacted me with a fascinating idea and a unique example of a Sankey diagram. He writes: “I accidentally “reinvented” the Sankey wheel quite awhile ago for a rather odd usage: political party ebb and flow in E. Europe.”

This diagram he presented in a recent post on his Pozorblog shows how parliament seats were allocated to the different parties in the Slovakian parliament from 1990 to 2008, and how seats were shuffled during the six elections that took place during that time.

“As with energy, the number of party seats in parliament is a closed system and there are flows from some to others. This is a highly modified usage, of course, as we do not know in a precise way “where” votes go from one election to the next, so we just fudge at the day of election and just start over (or have invisible reallocations).”

Have a look, for example at the brown brown arrow: The HZDS party has clearly been on the loosing track. On the other hand SMER (shown in orange), a party that emerged as a spin-off from SDL (pink) in 2000, could gain a significant number of seats in the 2002 elections, when SDL couldn’t make it into Slovakian parliament any more. Others pretty much remained stable in their number of seats over the whole observation period.

I am not sure if Kevin uses the “official” colors of the parties (wouldn’t mind tossing my vote for the pink party 😉 ), but a color clustering would also allow to visualize if left, or right, or liberal, or whatever political direction gets stronger or weaker. It would also be a possibility to see, if there is an overall trend in a certain group of countries, such as Eastern Europe, or the apparent growth of socialism in South America.

I am calling for votes on how to name this special type of Sankey diagram. If the first Sankey diagram was for steam power, why not a power Sankey diagram? 😉

Substances in Wastewater Treatment

In the Wiki of the CD4WC (Cost Effective Development of Urban Wastewater Systems for Water Directive Compliance) project, I found an interesting Sankey diagram that I wanted to share with you.

This project, funded by the European Commission, deals “with optimising the efficiency of urban wastewater systems with regard to ecological consequences in natural water bodies and with regard to investment and operation costs.”

The waste water treatment process system is shown with a schematic flow diagram. For individual substances that can be found in the waste water, the diagram is then displayed with Sankey flows, that represent the quantity. Thus, Sankey diagrams are a possibility for the “determination of fluxes of substances per unit of time”. This presentation is part of a method is coined Substance Flow Analysis.

This presentation is very advantageous: The nodes in the system (the process blocks) remain at the same position, only the magnitude of the arrows changes, when switching to the substance flows view. Flows with large quantities substances are clearly visible.

It would also be a possibility to introduce as a third view (next to absolute water quantity, and substance quantities) the substance concentrations (impurities per m³ of waste water).

World Internet Bandwith Sankey

The cutting of two submarine internet cables in the Mediterranean Sea at the end of January, and another one in the Persian Gulf a few days later, was widely reported in the news. The cuts affected internet services and call center operations in large parts of the Middle East and India, sparking discussions about emergency backup plans for offshore software development.

This reminded me of the internet traffic maps I had seen on the Web before. These are available as traffic load maps as well as bandwidth capacity maps of the backbone infrastructure.

Indeed these maps can be considered as fine examples of Sankey diagrams, with bi-directional (or non-directional?) arrows whose magnitude represent the bandwidth of the transcontinental internet cables. Additional arrow colors could be used, for example, to represent ownership or operation of the cable by different companies.

At the same time the Sankey maps may also serve to indicate communication technology development in different world regions.

BTW, if you want to stick one of these maps prominently on your office wall, they are available as posters here.

Bioclimatic Construction – mais oui, avec Sankey!

The French architecture company AMEO is specialized in construction bioclimatique. The term is probably best translated as ‘bioclimatic building’ … but sound much more chic in French!

The houses they build are made from environmentally sound materials (mainly wood, and other materials such as and cellulose-based materials) where ever possible. Local micro-climate is taken into account, and passive solar energy is used for heating.

Sankey Diagram for a Bioclimatic Building (Source: AMEO Architecture)
Used with permission of AMEO – Source: http://www.ameo-architecture.com

The company presents energy gains and losses and the advantages of the bioclimatic building to their customers using Sankey diagrams as the one shown above. Unfortunately two of the flows have no quantity indicator, and two of the quantity shown in the labels have probably been switched (see thin flow labeled 13779 kWh, but wide flow labeled 5850 kWh). However, I like this diagram for its simplicity.

Chemical Reaction Sankey

This rather simple Sankey diagram represents the idealized mass balance for making ammonium bicarbonate. The chemical reaction is H2O + NH3 + CO2 → NH4HCO3. It is taken from a Polish web page on chemical process technology.

The diagram is drawn with the freeware Sankey Helper. And it is nice to see that, while most of the Sankey diagrams are drawn with a left-to-right flow orientation, this one is top-to-bottom.

Material Flows in the U.S. Food System

If you enjoy browsing for tidbits of interesting information on the web, I highly recommend the collection of fact sheets on the website of the Center of Sustainable Systems (CSS) at the University of Michigan. This series of 2-page papers on topics, such as energy, water, waste, transportation or buildings, targets at the ordinary citizen and presents scientific information with bulleted list of interesting facts, nicely illustrated with diagrams, and sometimes recommendations for individual behaviour (“What You can Do”).

The fact sheet on the U.S. Food Chain shows the material flows for providing food in a Sankey diagram. Data is from 1995, the flow quantities are in million pounds.

The inputs from the left are limited to crops, feed and pasture. Other inputs such as water, fertilizers, etc. are omitted. The actual quantity of food consumed by U.S. citizens is shown on the pink arrow (355,880 million pounds). Exports of food are shown in blue and are about the same size (355,560 million pounds). A large portion of material into the food chain goes into “respiration, animal losses and live animals” (the latter probably being fed back into the food chain at a certain point, I assume, so consider them a foodstock. ,-)

There is much more to find in this Sankey diagram. So why not take a few minutes of your lunch break to explore it and read the full fact sheet. And while your at it, why not eat a locally grown apple while doing so …

Diagramas de Sankey? Si Se Puede!

The Mexican National Commission on Energy Saving (Comisión Nacional para el Ahorro de Energía (CONAE) present several success stories (casos exitosos) on their website.

One success story dates back to 1997, and describes how an energy efficiency study of fired heaters (i.e. boilers) was carried out in a Nafta producing facility in the Veracruz state of Mexico. As a result of the study, several suggestions for optimization were implemented. Fuel consumption could be reduced by 23-24 %, while the efficiency of the ovens could be raised by 13% (calentador BA-2001 B) and 16% respectively (calentador BA-2001 A).

Para los hispanoparlantes: el título oficial del proyecto fue “estudio técnico económico e ingeniería conceptual realizada a los calentadores a fuego directo BA-2001 A/B de la planta hidrodesulfuradora de naftas, del C.P.Q. “La Cangrejera”, ubicado en Coatzacoalcos, Veracruz” (otro candidato para el concurso mundial de titulos largos).

The heat losses are shown as Sankey diagrams. The first describes the optimal situation, with an energy efficiency of 82,4 % “as guaranteed” by the maker of the fired heater.

The two other Sankey diagrams show the energy balance of the heaters A and B before the implementation of the measures. They run with an efficiency of 60,6 % and 62,35 %, a “real world situation of one fired heater” /

The arrows branching off at the top show the heat losses. I like the fancy icons that show how energy is lost through the walls, because of deteriorated or insufficient insulation, and heat energy in the effluent gases. The flows are given in MMBTU/h (millions of BTU per hour).

Unfortunately two of the diagrams are not to scale: The arrow to the right in the second diagram should be roughly 2/3 of the width on the left side. It is about 4/5 (or 80 %) of the width, similar to the width in the first Sankey diagram. This is a visual exaggeration of the inefficiency. However, I refrained from featuring this in my informal “Lying with Sankey diagrams” series. 😉

Edit 05/2015: the web pages are not acessible any more. I had to restore the image from a local copy, and removed references to two other diagrams I had references to. -Phineas

Sankey Diagrams with Visio

Chris Roth, the Visio Guy in his latest article focuses on the question whether and how Sankey diagrams can be drawn in Microsoft Visio.

Can Visio do Sankey? While there are no Sankey Diagrams templates that ship with Visio, there are a few in-the-box shapes that can be used to create rudimentary Sankeys.

He identifies some problems with the Visio-supplied arrow shapes, and provides “a new version of the arrow shape which is more suitable to making Sankey diagram” for download. Really cool, Visio Guy!

In one of the follow-up comments Chris states that pre-built shapes can only cater for the most basic Sankey arrows, but “a proper, full-blown solution would utilize at least some code, if nothing else, for decent data-input dialogs, etc.”