A research project at Technical University Dresden in collaboration with a paper manufacturer aims at detecting and implementing energy saving measures for paper machines.

“Better monitoring of process variables, improvement in the operating point (or range) of the process, installation of heat recovery systems (e.g. at heat exchangers), use of heat pumps and replacement of high energy streams (steam) with waste heat streams. Most of these techniques are standard recipes which are readily available in the market. However they are designed without giving any consideration to the specific aspects of a manufacturing facility and also provide no quantitative evidence of the potential benefits. “

This is why they came up with a mass and energy balance model and are using the following Sankey diagram to visualize where energy could be recovered.


Flows are labeled as enthalpy flows, showing the changes in thermodynamic (heat) energy at each process step, hence losses. The Sankey diagram is for a balance period of six hours. No absolute figures are given. Several heat exchangers are installed along the wet section of the paper machine. In the drying section, a large part of the energy is lost as steam/humid air.

I am aware that I was kind of ‘Sankey diagram bashing’ with my post on Spain energy flow diagram last December. Now here is another one from the Iberian penninsula that fully makes up for the first one. It is by Observatorio sobre Energía y Desarrollo Sostenible (Observatory of Energy and Sustainability in Spain) at the Universidad Pontifícia Comillas in Madrid. I find it noteworthy that the observatory is part of a BP financed chair at the Escuela Técnica Superior de Ingeniería (ICAI).

The annual report 2010 includes three Sankey diagrams, two of which are shown below. The first Sankey diagram (p. 16 of the report) has the typical pattern of a ‘national energy consumption, conversion and use’ diagram, similar to the ones presented here on the blog several times already for other countries.

The flows from the left show energy sources, the nodes on the right are the use sectors. A nice feature here is that the node heights are adapted to the magnitude of the Sankey arrow, so that the largest energy consumption can immediately be seen. Flows are in in Exajoule (1 EJ = 1000 Petajoule = 10E18 J). The total primary energy consumption in Spain in 2009 was 5.86 EJ (4.95 EJ of which are from imported fuels). Also shown next to the absolute quantities is the relative share of each flow in percent, and the change in comparison to the previous year.

The second Sankey diagram (p.22) is what I would call a value stream Sankey diagram.

This is interesting as the market price for the fuels, as well as for converted energy is used as a weighting factor, so that each Sankey arrow shows the value of the energy flow in millions of Euro. At some nodes you can see that a smaller arrow enters, and a wider arrow leaves: These are the conversion processes where value is added (or energy gets more expensive). This is a compelling concept for a Sankey diagram (another similar example is here), one that somehow could make Sankey diagrams more interesting for economists or controllers, rather than considering them exclusively in the engineering domain.

The third diagram (not shown here, p. 19 in the report) shows the embodied carbon or the greenhouse gas emissions related to the different fuels, broken down by fuel and sector of energy consumption. The embodied carbon in the energy carriers were roughly 285 Mtons in 2009. The Sankey arrows for renewable energy sources as well as for Uranium are not present in the third diagram.

Me gustan mucho estas tres diagramas de Sankey! Merecen elogío.

From Fei-Ling Tseng’s design blog comes this Sankey diagram. Her post is on some visualizations and infographics done for a project on water economies/ecologies of the Colorado River water system.

The diagram shows the distribution of water from the Colorado river to different lower basin states (Nevada, Arizona, California), “export” to Mexico and a breakdown to irrigation areas within California. The quantities are in acre feet (a.f.). Underlying data is from the Colorado River Accounting and Water Use Report 2009.

Simple, beautiful, conveying the message … and a single white water-drop as catchy design element.