UNDERSTANDING the intricacies of a domestic energy market is hard. It might entail production and consumption, imports and exports, different types of power sources, subsidies and more.

Glen Newton, a software developer in Canada, has done a splendid job of disentangling some of the elements by way of a so-called "Sankey diagram" of Canada's energy flows. It breaks down the constituent parts of the country's energy supply in a way that one can see things like the proportion of consumption to production to imports, as well as forms of fossil fuels. (We reproduced a small static image here; the actual version on Mr Newton's site is interactive, so one can adjust nodes or mouse-over the flows to see the actual amounts.)

The diagram shows, for instance, that in 2007 (the latest data from Statistics Canada that Mr Newton had access to) the country produced slightly more natural gas than crude oil. Also, industry consumes around a third more energy than the residential and farming sectors combined. The data points to the gains that may be possible from energy conservation by industry, and the paltry use of green technologies.

The data-visualisation technique was named after Matthew Henry Phineas Riall Sankey, an Irish engineer in the British Army, who in the late 19th century devised the method to show the flow of thermal energy in a steam engine. Ironically, Mr Newton's use of the flow-diagram represents a sort of homecoming: Sankey himself spent a few years at the Royal Military College in Kingston, Canada.