Kevin Anderson has a chart he uses to argue for demand-side reduction of energy use as a powerful way to achieve emission reductions of greenhouse gases. That chart is:

It is derived from the IPCC AR4 Working Group 3 Report, in Chapter 4, as Figure 4.3, and it cites Professor Don Cleland of Massey University as a reference. A presentation containing the same figure was made at the 2006 IPS Roundable, and is reproduced below:

What it shows is that to produce electricity going into powering a lamp (sometimes called “end-use energy”) a unit of lighting, 98% of the generated energy (sometimes called “net generation”) is lost and over 99% of the energy in the original fuels are lost (sometimes called “primary energy”). The figure also shows that 75% of the generation energy is lost during transmission to the residence housing the light bulb. This is derived from Professor Massey’s contribution to the proceedings of the the 2004 People and energy: how do we use it? New Zealand conference including an analysis of light bulbs using Sankey diagrams. The application to a light bulb is described at a Web site devoted to applying these diagrams. It includes:

Accordingly, if energy is generated at the residence,

There are even dynamic versions of these diagrams available, for instance, this one considering heating of a home:

Naturally, the same kind of diagram can be constructed for wind turbines:

This is taken from Koroneos and Katopodi, 2006.

(Update, 20^th April 2016)

Sankey diagrams also have uses in Statistics, Data Science, and Machine Learning, as Simon Raper shows. And see here for many examples of Sankey diagrams. For instance,

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(Update, 23^rd May 2016)

It’s odd that, apparently, sophisticated financial analysts like Steve Cicala don’t understand the implications of Sankey inefficiencies. John Farrell responds.