This Sankey diagram is pretty much messed up, and definitely a candidate for the “Worst Sankey Diagram Contest” that has already been called for. It took me a few seconds to understand that the flows dangling vertically below the blue arrow are actually a breakdown of the 177 mtep consommation finale. Vraiment … j’ai vu mieux que ça!

This is more or less how I would do it. Less colors, a breakdown of the blue flow into the five consumption sectors.

These energy balances are apparently produced annually by French DGEC (Direction Général de Énergie et Climat) and are different from the energy flow Sankey diagrams for various countries I have shown here in other posts.

In these French energy balances the left side shows the primary energy (expressed in mégatonne équivalent pétrole Mtep, mega tonnes of oil equivalent Mtoe in English) broken down into the different sources, the right side shows the final consumption of energy with the same breakdown. The differences are the energy losses and internal consumption in energy generation.

The large losses for nuclear energy are explained in a footnote for the 2007 diagram, where it says that these can be attributed to the fact that ‘Observatoire de l’Énergie’ (OE) accounting standard is based on heat value:

L’importance des pertes dans le domaine de l’électricité tient largement au mode de calcul adopté depuis 2002 par l’OE: l’électricité d’origine nucléaire est comptabilisée, au niveau de la production, en termes de chaleur, dont les deux tiers sont perdus lors de la conversion en énergie
électrique

Nevertheless the Sankey diagram gives a good idea about the efficiency of energy generation for each of the different fuels and the energy mix for France.

For those of you who wish to compare the developments over the last years, here is what I have dug up so far:
2003 is shown on Planete Bleue in this post.
2004 is shown above
2006 can be found here on page 25 (PDF)
2007 can be found here on pages 6/7 (PDF)