Have been very busy recently and have neglected the blog. Here’s just a quick one (to get some color on the top post again … 😉 )

UK’s Department for Environment, Food and Rural Affairs (DEFRA) has crowned its new website on combined heat and power generation with a nice Sankey diagram.

What is CHP? “CHP systems are highly efficient, making use of the heat which would otherwise be wasted when generating electrical or mechanical power (…) and typically has an efficiency of over 80%”, the accompanying text explains.

The diagram is built similarly to this one presented in a previous post: The Sankey diagram doesn’t feature absolute figures, but flows are scaled in relation to the baseline of 100 units energy generation in a power plant and a CHP unit. In a cogeneration unit 160 units of energy would be produced at the same time. Losses are accounted for with 65 units in the CHP. To produce the equivalent energy quanities in a conventional power unit would cause losses 1.65 times higher than the energy output itself. In the boiler 25 % of the energy is lost (40 units).
Overall losses in convential generastion are 205 units compared to 65 units in a CHP.

Sam Brenner, interactive design and development student at the Rochester Institute of Technology, has finished version 0.2 of his ‘Sankey Generator’ tool.

Inspired by state federal budgets Sam pursues to display financial figures in a clear and comprehensible way. Sources of state income are on the left, spendings on the right. As Sam says himself, this is still work in progress. “I’m trying to make a dynamic Sankey Diagram generator (…) What I would like to end up with is a program that can take numeric data like a budget and turn it into a diagram…”.

See that small step at the bottom of the middle part? Hey, here you have the “deficit”…

Interesting new tool. Not sure if the Sankey Generator tool will reach a status that would allow Sam to release it publicly, but have added it to my Sankey software list anyway. Hope version 0.3 has some fancier colors, though 😉

After the rather complex Sankey diagrams presented in my previous post, here’s another comparatively simple one. It is presented on the website of consulting and planning company UMTAS in Germany, to support their services offers in the field of material and energy flow management.

The diagram is just symbolic and doesn’t indicate any absolute quantities or a time period. It merely shows the compsition of waste.


The process labeled “compost plant” seems to be a kind of sorting station, where non-compostable items such as metals are being removed. Hospital waste appears to be absent and the arrow line is shown dotted. The input and output flows of the compost plant don’t seem to match – or is this just a trompe d’oeil?

In fact, the information conveyed in this Sankey diagram is no different from a typical pie chart. [This reminds me of a categorization of Sankey diagrams I had on my to do list]. Still, I think it is a valid representation of the data, and the diagram will get even more interesting, if one starts to study where the waste flow outputs are going to and how they are treated.