Does the average American use more energy than a blue whale?

August 19, 2011

Dear Cecil:

Does the average American use more energy than a blue whale? The New York Times says it’s true. Is it?

Cecil replies:

We need to clear up a couple levels of confusion here. First, the New York Times didn’t say the average American uses more energy than a blue whale. The paper quoted someone as saying this. The Times doesn’t have a policy of only quoting people who say true things. If it did, all coverage of politics would come to a screeching halt.

Second, the more pertinent question isn’t whether this is true. It’s who the hell cares? The average American sits at the top (or the bottom, depending on how you look at it) of a vast industrial enterprise that has harnessed a sizable percentage of the earth’s resources in the service of our present rock and roll lifestyle. The average whale swims in the ocean all day and eats krill. If you’re telling me the latter approach has less impact on the planet, I’m not going to argue with you. But if you’re offering it up as a model we human spendthrifts can learn from, all I can tell you is it’s going to be a tough sell.

Nonetheless, here we are, tackling the issue anyway. Why? Blame my assistant Una. So what if this line of investigation is in basic respects inane, she said. It would still be cool to know.

The Times piece you refer to, “A Physicist Solves the City” (it ran in the magazine section last December 17), describes the work of physicist Geoffrey West, who compares himself to Isaac Newton and claims to have discovered the mathematical laws that govern how cities work. West thinks urban living, while intrinsically energy-efficient, nonetheless drives up overall power consumption, to the point where Americans now burn through energy at a rate of 11 kilowatts per person. “What you find is that we have created a lifestyle where we need more watts than a blue whale,” the Times quotes him as saying.

To ascertain the truth of this, we first looked into the human end of things. According to the Department of Energy, gross energy use for the U.S. is about 103 quadrillion BTUs per year. If we divide this by the U.S. population, then convert it into continuous average energy use, sure enough, we end up with about 11 kilowatts per person.

Next we checked the energy requirement of a blue whale. Here we ran into a problem. According to estimates published in 1981 by the distinguished marine biologist Christina Lockyer, a blue whale weighing around 80 tons has a basal (resting) metabolic rate of about 12 to 25 kilowatts.

Aha! said Una. That’s more than humans, not less. West screwed up.

Come now, I said. It’s in the ballpark. This fellow West has done high-profile work on animal metabolism and is clearly no dope. Parties of his stature don’t make mistakes; they merely misspeak. We’ll assume he meant to say we use almost as many watts as a (smallish) blue whale, not more.

Fine, said Una, make excuses. But it’s still not fair to compare per-person energy consumption for all human activity in the U.S. with the resting rate for blue whales. Whales are plenty active — ask Captain Ahab. Perusing the biological literature, we find disagreement about the active metabolic rate of blue whales, but the conservative figure seems to be three times the basal rate. In other words, an active 80-ton whale might consume energy at a rate of 36 to 75 kilowatts, considerably more than the average American.

But that’s misleading too, she continued. Problems: (1) Whales aren’t always active. (2) Typical size for a mature male blue whale is more like 107 tons, not 80. (3) Computation of per capita U.S. energy consumption is based on gross usage — how much energy gets pumped into the system. But not all that energy finds its way to us; some leaks away. Likewise, the prodigious quantity of krill eaten by a blue whale isn’t all digested; some is wasted. The true comparison, therefore, should be per capita U.S. energy consumption vs. how much food a whale actually eats.

I conceded the wisdom of this. We turned again to Lockyer. She calculates that a 107-ton young adult male blue whale (who eats less than the female) consumes 491 million kilocalories annually. That works out to a continuous rate of 65 kilowatts. So the average American doesn’t use more energy than a blue whale, but rather much less.

OK, I said, but 11 kilowatts per person is still a lot. Assuming the average blue whale weighs 1,200 times what the average American does, pound for pound the American is using roughly 200 times as much energy as the whale, an ominous-sounding ratio sustainabilitywise.

True, said Una. But there’s another way of looking at it. For all our frantic consumption of resources, there’s a simple creature of the ocean that uses six times as much.

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References

Estes, James A. et al. Whales, Whaling, and Ocean Ecosystems Berkeley: University of California Press, 2006.

Goldbogen, J.A. et al. “Mechanics, hydrodynamics and energetic of blue whale lunge feeding: efficiency dependence on krill density” The Journal of Experimental Biology 214 (2011): 131-146.

Lehrer, Jonah. “A Physicist Solves the City” New York Times 17 December, 2010.

Lockyear, C. "Growth and Energy Budgets of Large Baleen Whales from the Southern Hemisphere" in Mammals in the Seas: General papers and large cetaceans Food and Agriculture Organization of the United Nations. Working Party on Marine Mammals. Rome, 1981.

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