> Many different units are used to discuss large quantities of energy. The graph above uses “quads”, or quadrillion (10^15) British Thermal Units. The SI unit of energy is the joule, and a comparable quantity is the exajoule (EJ),
Why use “quads” instead of exajoules? I really don’t understand the use of non-SI units in cases like this, it seems like pointless obscurantism. Using something like terawatt-hours, well that isn’t SI (although it is based on SI), but I can at least see the point to it. But “quadrillion BTUs” and calling that “quads” doesn’t seem to serve any useful purpose
It's explained in the post. It makes the total amount be roughly 100 quads, which makes it easy to estimate all the numbers in the graphic as percentages.
Given an exajoule and a quad are close in value, you’d get roughly the same result with exajoules instead.
Also, the fact that total US energy consumption is currently roughly 100 quads is only a passing coincidence - it would not have been true in the past and will not be true in the future. It is weird to justify choice of unit on the basis of a temporary coincidence in the data
> The post is about a specific point in time, not for all time. So there's nothing wrong with taking advantage of a temporary alignment in the data
The choice of quads as a unit was not made by the post author (John Walker), it was made by a US government agency (the EIA) and a US government-funded research lab (LLNL). Walker appears to have only chosen quads because of the use of quads by the convenient graphics those agencies have produced. The idea that they are using quads due to a “temporary alignment in the data” seems like a post hoc rationalisation - what unit were they using before this temporary alignment? Probably quads; and if not quads, then likely something else equally non-metric. It is unlikely the US government would have already been using SI units (or even a non-SI metric unit), then suddenly switch to a non-metric unit just because of a temporary alignment in the data; much more likely they use quads because that is the US government’s standard unit for this purpose, and already was long before this.
And to be clear, I’m not criticising Walker for choosing a convenient freely-usable graphic to illustrate his point, even if it is in weird units; I’m criticising the US government for its continued clinging to weird units like “quads” that almost nobody else in the world uses, when there is no good reason for them to do so.
Why use “quads” instead of exajoules? I really don’t understand the use of non-SI units in cases like this, it seems like pointless obscurantism. Using something like terawatt-hours, well that isn’t SI (although it is based on SI), but I can at least see the point to it. But “quadrillion BTUs” and calling that “quads” doesn’t seem to serve any useful purpose