Human vs Blue Whale energy consumption, revisited

Cecil's Columns/Staff Reports
1

Dear Cecil:

In the column “Does the average american use more energy than a blue whale”, I’d like to argue the point that the logic used is a bit flawed.

You compare average per-person “energy” usage in the United States to the metabolic rates of a blue whale. The statistic for average per-person energy usage come from the Department of Energy, but I’m pretty sure if Department of Energy factors in the metabolic rates of Americans into their statistic, so how can you use that to compare against the metabolic rate of whales?

Now sure, the diesel fuel used to plant, harvest, and transport alot of our food, and the electricity that the mass pig death machines and the animal paste grinders use to bring us our hot dogs is factored into that number. But what about the sun’s energy that goes into the plants that make up our diet, and the diets of the animals we eat? That’s certainly relevant, if we are going to include a whale’s diet in the comparison of energy consumption.

Also, what about all the energy that goes into making all the foreign-made products we buy? I mean, they certainly used plenty of energy to make all this crap from China that our houses are filled to the brim with, but that energy isn’t reported as part of the U.S. Department of Energy’s statistic is it, even though the end product is consumed by Americans?
So, I think we can probably agree that it would be difficult if not impossible to really get an accurate number of average KWH worth of energy consumed by an American if you factor in the things discussed above, among other things that I didn’t think about.

Why then in your column do you present such clearly insufficient statistics as if they were somehow meaningful?
P.S. I’m a big fan of your columns.
-Jim, Baltimore

2

Wouldn’t the same sun be providing the energy for the krill the whales are eating too? That seems to me to be a wash.

3

I made several grammatical errors, and by the time I cleaned them up, it wouldn’t let me edit my post anymore because the 5 minute limit was up.
So please allow me to make the corrections in a reply…

http://www.straightdope.com/columns/...n-a-blue-whale
Dear Cecil:

In the column “Does the average american use more energy than a blue whale”, I’d like to argue the point that the logic used is a bit flawed.

You compare average per-person “energy” usage in the United States to the metabolic rates of a blue whale. The statistic for average per-person energy usage comes from the Department of Energy, but I’m pretty sure the Department of Energy does not factor in the metabolic rates of Americans into their statistic, so how can you use that to compare against the metabolic rate of whales? What about all the food we eat?

Now sure, the diesel fuel used to plant, harvest, and transport alot of our food, and the electricity that the mass pig death machines and the animal paste grinders use to bring us our hot dogs is factored into that number. But what about the sun’s energy that goes into the plants that make up our diet, and the diets of the animals we eat? That’s certainly relevant, if we are going to include a whale’s diet in the comparison of energy consumption.

Also, what about all the energy that goes into making all the foreign-made products we buy? I mean, they certainly used plenty of energy to make all this crap from China that our houses are filled to the brim with, but that energy isn’t reported as part of the U.S. Department of Energy’s statistic is it, even though the end product is consumed by Americans?

And what about all the energy that’s used in America to produce a product that is exported and consumed in a different country? Should we be including only energy that is first-hand consumed by an American, in America, even if the end result is consumed elsewhere? And vice-versa? (if you’d like to give an etymological history of the term vice-versa, I’d accept that as an answer as well)

So, I think we can probably agree that it would be difficult if not impossible to really get an accurate number of average KWH worth of energy consumed by an American if you factor in the things discussed above, among other things that I didn’t think about.

Why then in your column do you present such clearly insufficient statistics as if they were somehow meaningful?
P.S. I’m a big fan of your columns.
-Jim, Baltimore

4

That’s the point. If you include the amount of energy that a whale consumes by way of eating krill in the statistic of how much total energy a whale uses (and in fact that’s the ONLY thing included in the statistic on the whale side of things), how then can you get away with not including the amount of energy that an American consumes by way of eating all the stuff we eat in the statistic of average American energy consumption?

5

Welcome to the Straight Dope Message Boards, JHuff, we’re glad you found us. I’m not qualified to comment on whales, but I would like to just let you know that we have a five-minute editing window. You can “preview” posts before submitting, which gives you unlimited editing time. And also, since we all know that we have a limited editing window, most reasonable folks don’t care much about typing goofs. We all do 'em, and no big deal.*

If you’ve made a dismal typing error (like “not” instead of “now”, say) you can email any moderator (or hit the REPORT button – the little ! in a red triangle in upper right corner of the post) and we can fix for you.

Anyhow, welcome!

  • [sub]Yes, there are some exceptions who make a big whoop-te-doo about typos. Anal compulsives, pay 'em no mind. [/sub]
6

Some of these calculations I do for part of my job. Here’s some food for thought.

About 90% of energy is lost on each stage of the food chain. A whale feasts on krill and small fish. Krill feast on smaller zooplankton (copepods and microbes) who feast on phytoplankton, who feast on the sun. So sun -> phytoplankton -> zooplankton -> whales losing 90% per step. So every unit of whale weight takes 1000 “sun units” of production (3 steps) to create. That’s neglecting the fish that they might eat which would make it higher. We, on the other hand eat mainly plants, and then herbivores (and very small amounts of carnivores, mainly fish). Let’s say we eat half and half. So each human weight unit takes the average of 1000 and 100 to create, 550 sun units, or half that of a whale per unit of weight.

Now that’s “per unit weight”. If a human weighs 75 kg, and a whale weighs 100 metric tons, you’ve got a ratio of 1 to 1300 (human to whale) or, factoring the food chain above, say 1 to 2600 units of sun energy used between one human and one whale. (going the next step, includes relative digestibility of foods, relative metabolism as the ocean is colder, etc. probably wouldn’t change the order of magnitude here).

Of course, as mentioned, the humans would gain their own back comparing use of fuel for farming, transport, etc. These numbers can vary wildly so I’ll see if someone else wants to calculate how much of the 1/2600 deficit we earn back that way.

7

Thought of another way to answer the question on the drive home.

A human eats 2000kcal/day. Let’s double that for direct food loss (indigestible stuff, husks, bones, etc.) to 4000kcal/day.

That’s 4.65kwH in a day. Using Cecil’s numbers, 11kw * 24 hours is 264kwH/day for the energy use he used. Or if you prefer continuous, that’s 11kw versus 11.19 kw.

That’s really in the range of error.

How about the energy to produce food? Well, Cecil included it, because he used the total energy use of the U.S. divided by its population. Leaving out imported food, including it again would be double-counting.