Sankey Diagrams

The below Sankey diagram is shown on a webpage of HAW University of Applied Sciences. It shows the generation path of hydrogen from natural gas, and the overall energy yield.

Unfortunately the diagram is too small to grasp the details. The Sankey arrows represent energy content. Losses are shown as black arrows. This seems to have been the result of a study project dealing with a fuel cell driven boat (ZEMSHIPS).

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.

In a report on “Fuel and financial savings for operators of small fishing vessels” by J.D.K. Wilson from Maputo, Mozambique (available on the FAO website), the author explains that in a small slow-speed vessel, only approximately 35% of the energy created from the burning of fuel can actually be utilized to run the propeller, thus can be “spent on useful work such as pulling the net”.

I have “translated” the given values into a Sankey diagram, using the original image as a background layer. This works quite fine, apart from the very thin (1%) flow of friction losses.
On a side note: this is the first time I am presenting a right-to-left oriented Sankey diagram on this blog.

The author concludes, that energy can be saved on the engine and transmission, however the mode of operation (e.g. to reduce the effect of wave resistance), and hull maintenance. Read more interesting details.