Responding to Wayne Hodgins:

This example shows how elusive the concept of simplicity is.

As one commentator has already pointed out, the measure of '1 cubic mile' is needlessly complicated for a a world based on SI.

Moreover, '1 cubic mile' is meaningless as a measure. Nobody knows how much oil '1 cubic mile' represents. It is a unit outside our comprehension. Consider: off the top of your head, how many barrels is it? How many homes does it heat?

Third, the concept of 'oil' is not static. Oil comes in different types, some of which create more energy than others. Is the '1 cubic mile' West Texas Crude? Or what?

Fourth, one wonders how using a measure of volume clarifies a measure of energy. In an energy-conscious world, it may make more sense to educate people about joules than it does to make them imagine cubic miles of oil.

Keep in mind that one joule is the work done to produce power of one watt continuously for one second; or one watt second. And people *do* understand the concept of the kilowatt-hour - it shows up on their electric bill every month.

The main argument for the proposed system (ie., that we use a CMO as a measure) is that it is too difficult to use other measures. Of course, when they are stated as poorly as the authors state them, one cannot help but wonder why.

Consider, for example, "The Three Gorges Dam is rated at its full design capacity of 18 gigawatts." per yer? Let's suppose so - the authors don't say.

Then in the diagram we see that 1 CMO is equivalent to '4 Three gorges dams every year for 50 years'. Huh? How many Three Gorges Dams is that for one year? 200. Why not say one CMO (which is burned in one year) is equivalent to 200 dams (which produce 18 gigawatts per year).

Or, in other words, 36,000 gigawatts per year (gigawatt-years). One year is about 1 year = 8766 hours. That's 315 576 000 gigawatt-hours. That's 315 petawatt-hours, or 0.3 exawatt-hours (I'll leave the conversion to joules to you).

People can handle mega and giga (they do it when they use computers every day). The way things are going, it won't be long before they handle tera and peta. And - nicely - their system for counting units of energy will be the *same* as the one they use to count units of memory. And units of other things.

And what's so complex about 315 petawatt-hours? Nothing.

Looking at this article, I am face with two questions:

1. Why did the authors use oil as a standard?

2. Why did the authors use the mile as a standard?

It seems to me that such a nomenclature makes people think of energy in terms of imperial units and in terms of petroleum products.

And it makes everything else look like a *lot* - compared to the oil. It only takes *one* oil to make up 32,000 or so wind turbines (for 50 years).

How we talk about something says a lot about how we think about something, which is why there are such disputes about standards and nomenclature.

From one point of view, the use of CMO is 'simple'. From another point of view, the use of CMO is politically loaded and culturally specific.

That's why standards are so hard, and especially why discussions of them shouldn't be limited to engineers and should be presented as a "wonderfully short and simple article" in IEEE Spectrum.

Some of your terminology is confusing.

ReplyDelete"Watts" measure *power* or the *rate* of energy transfer (or rate of work).

"Joules" measure energy.

So it *is* correct to say the Three Gorges Dam has an output capacity of *18 gigawatts*. So, (running at full-capacity), in 1hr it would produce 18 gigawatt-hours of energy, in 1yr it would output 18 gigawatt-years.

One comprehensible comparison might be "the dam could light 180million 100-watt light bulbs".

Another might be "in 1hr, the dam generates as much energy as 500k gallons of gas". (actually 486,486 if you use 37kwh/gallon).

http://webseitz.fluxent.com/wiki/EnergyAccounting