The power budget

[snousle]

I am repeatedly surprised by energy statistics. I've spent lots of time calculating the costs of various things in my immediate environment, so I was astonished to read that the US as a whole uses about three terawatts of power on average. That's ten kilowatts per person! The average American uses about 1.4 of those kilowatts in gasoline. So automobiles - which are profligate energy consumers - are still only a fraction of the total power budget.

The human body uses only about 100 watts, and if you really exert yourself it is possible to generate about a kilowatt for short periods. A horsepower is also of the same scale, with one horsepower being about three-quarters of a kilowatt. Our house, with three people, uses about a kilowatt of electricity. It boggles the mind to consider that the machinery around us, whose work we appropriate to ourselves, is like an invisible slave galley with the power of a hundred men working twenty-four hours a day on our behalf. Or, less dramatically, a hundred very bright incandescent bulbs in some gigantic vanity mirror.

I hear a lot of that power, about half, is used for "buildings", which is a pretty broad category, and I'm not sure how it breaks down into heating, cooling, lights, and so forth. But for the life of me, I can't figure out where even the remaining half is going.

Comments

[sinnabor.livejournal.com]

Uh, 3 terawatts per hour? Per day?

Lots and lots of power goes into fixing nitrogen for fertilizer, right?

[sinnabor.livejournal.com]

Oh, wait, nevermind. Watts is a rate, and that's what you're comparing it to.

Aside from fixing nitrogen, isn't much of the price we pay for food spent on shuttling it around from place to place and running open-fronted coolers at the store?

[snousle.livejournal.com]

Food transportation is a very small fraction of energy use. And the whole "food miles" thing is a greatly misplaced concern; by far the most wasteful use of energy in food production is between the grocery store and the home.

The Heber process for nitrogen fixation is something like 1 or 2 percent of global energy use.

I have no idea of the cost of grocery store refrigeration. Maybe that's the missing 50 percent!

[tmaher.livejournal.com]

Tony, can you point me at the stats you saw? I'm really curious now, and I'd like to see if they offer any breakdown of what is/is not counted.

For example, consider the power used in a Chinese factory to make stuff for the US market. Should it count in the US's total, or China's? Do you count the solar energy a farmer (passively) uses to grow crops?

[snousle.livejournal.com]

There are a variety of sources. The three-terawatt number is from a recent article in Nature, but not recent enough that I have the issue at hand.

I believe that this is energy used in the US so Chinese consumption is not counted. And it's marketed energy, so no, solar use by crops is not included.

[furr-a-bruin.livejournal.com]

I just wonder where industrial uses come into that statistic. I realize it's probably a small part of the whole, but I know that aluminum refining is a very energy-intensive process ... hence the reason aluminum refining tends to be in areas with copious cheap power like the Pacific Northwest.

[broduke2000.livejournal.com]

When I used to pirate, I used a kilowatt. It took another kilowatt to modulate it.

The FCC took a dim view.