Sankey Diagrams

As a followup to last week’s post on a Sankey diagram from the GEA report. here is another one from the very same report (GEA, 2012: Global Energy Assessment – Toward a Sustainable Future, Cambridge University Press, Cambridge UK and New York, NY, USA and the International Institute for Applied Systems Analysis, Laxenburg, Austria).

This one is an example for losses along the energy supply chain.

The description of the diagram on pp. 116/117 says:

“As an example of energy chain efficiency, Figure 1.13 illustrates the energy flows in the supply chain for illumination services (lighting). In this example, electricity is generated from coal in a thermal power station and transmitted and distributed to the point of end-use, where it is converted to light radiation by means of an incandescent light bulb. Only about 1% of the primary energy is transformed to illumination services provided to the end-user.”

The Sankey diagram shows the primary energy as 100% on the left and branches out the losses at each conversion/transmission step. The actual useful energy (the “energy service” of providing illumination) is only 1%. So in this example one unit of energy service requires 100 units of primary energy, clearly pointing to “abundant opportunities for improving efficiency exist at every link in the energy chain” (p. 116).

I have presented a similar Sankey diagram here before, see this 2007 post ‘What it takes to power a bulb’.

At the Technical University of Munich a project on Engine Combined Cycle (ECC) Power Plants aims at “improving the electrical efficiency of an engine combined cycle plant by using the exhaust gas heat in a steam cycle”.

The following Sankey diagram is shown to illustrate where heat can be recovered.

No absolute values are given, but the Sankey arrows represent the percentage of the primary energy. Four percent of the energy in the steam process can be recovered to add a total of 47.8% efficiency output of electrical power to grid. Losses branch out to the right side and are primarily via the cooling water and condensate at the steam process. The whole Sankey diagam is presented in a simple single-color design.

Consumption of water resources in arid and semi-arid areas has become an important issue over the last years. The Wafeer water conservation project is trying to raise awareness and educate people in Saudi-Arabian industry in regard to the efficient use of water. On page 21 of their Water Efficiency Manual, the following Sankey diagram can be found:

The report describes that “Sankey diagrams enable visual representation of both quantitative and qualitative characteristics of water entering and leaving different activities and therefore serve as a good communication aid.”

The above diagram does not show any unit, but presumably is meant to be in cubic metres (per year?). It shows water (blue) and waste water (grey) flows, as well as evaporation losses (red).

More water Sankey diagrams of similar style can be found on pages 19 through 23 in this workshop presentation on ‘The Importance of and Difficulties in Water Accounting’.

Here is another one … enjoy!

Same topic as in my previous post, heat flows and losses, this time in a continous furnace. Recovered heat loop is strange: arrows gets wider in the curves, as if painted by hand. Funny serpent arrow for opening (radiation) losses. No values given. All arrows have the same colour. Source: Article ‘Quest for Fire – Combustion Basics’ by by Daniel H. Herring. Published October 2, 2009 on Industrial Heating. The International Journal of Thermal Technology.

I was busy with work, so hardly published any Sankey diagram related posts in the last two weeks. My cache of diagrams on my hard disk is very large, but the problem is to find time to discuss them and show them here. I have therefore decided to launch some miscellaneous Sankey diagram findings without much commenting…

Notes: Boiler Efficiency Sankey Diagram. Uncommon arrow head colouring. Percentage breakdown. Source: Energy Efficiency Analysis and Practices Blog. This Sankey is apparently produced by a software on boiler efficiency (BIOEFF v1.07), further analysis needed.

The 2007/2008 White Paper #154 Rev 1 published by APC explains “Electrical Efficiency Measurements for Data Centers”. The author points out that DCIE (Data Center Infrastructure Efficiency), defined as ‘IT Load Power’ divided by ‘Total Data Center Input Power’ is a good metric to analyse data center efficiency.

In fact, as can be seen from the Sankey diagram shown in the paper, the majority of electrical energy consumed in a data center is for cooling, UPS and other supporting infrastructure equipment.

No typical DCIE is given, but the samples shown suggest that it ranges between 30 and 50 %. Several constraints have an impact on the actual DCIE, such as the IT load itself and the outside temperature, and thus should be reported along with the measurement.

A nice idea to present the breakdown on electricity consumption as a Sankey diagram, rather than as a (boring?) pie chart, especially when speaking of “power flows”.

Download the WP #154 from APC’s website.

MAN Diesel, a renown producer of marine and power plant diesel engines, has been working on improving fuel efficiency of its engines. Today, the fuel energy efficiency is about 50%. The MAN Turbo Efficiency System (TES) allows to recover of heat from the exhaust gas, which is responsible for about 50% of the energy losses.

Here is a Sankey diagram that shows the recovery of energy from exhaust gas.

Download a description of the TES here (PDF, 291 KB) or view a high resolution version of the above Sankey diagram from their press picture gallery.

The World Business Council on Sustainable Development (WBCSD) in an article on “Making Tomorrow’s Building’s More Energy Efficient” features a great three-dimensional Sankey Diagram, to illustrate that “more than 90% of the energy extracted from the ground is wasted before it becomes useful work”. The article calls for green buildings where energy is produced onsite, and losses are minimized.

The Sankey arrows representing the losses bend down sharply, they remind me of the Iguazu Falls. Neat 3D images of the equipment are placed on the diagram to visualize the process steps where energy is lost. The whole thing hovers over the ground throwing a faint shade. The graphic designer who did this really merits an applause.

If ever I launch a ‘Best Sankey Diagram Award”, this one will have good chances to win it. Any sponsors out there? Any volunteers for the award jury?