Posted by: Joe Hoffman | July 27, 2009

Power Consumption and Life Expectancy

Power  The kind that turns on the lights and keeps you fed.

A man can produce two hundred fifty watts from his muscles for a reasonable length of time. When he has no more power, he is a savageLife Expectancy at Birth About 20

When he gains a kilowatt of energy from the muscles of a horse, he is a barbarian, but the new power cannot be directed wholly as he wills. When he can apply it to a plow he has a high barbarian culture, and when he adds still more he begins to be civilized.   Life Expectancy at Birth About 25

Steam-power put as much as four kilowatts to work for every human being in the first industrialized countries.  Life Expectancy at Birth About 30

In the Mid Twentieth Century there was about 60 kilowatts available per person in the industrialized countries.  Life Expectancy at Birth About 45

Nowadays, of course, a modern culture assumes 190 to 350 KW per person.  The US is right in the middle of that.  Life Expectancy at Birth About 80

These are just some back of the envelope calculations and do not take into account the power consumed elsewhere and used to create commodities and products imported into your life.


This is an interesting correlation.   More importantly than just from a historical point of view, the same relationships hold true today as you look at the same data for industrialized nations and less developed.  Life expectancy and power available are closely related.  But it takes an order of magnitude change in power to be reflected in LE.

The relationship here and similar relationships with GDP and family income present a problem for the Green Power movement.  The next power jump will will be to about 1 Megawatt per person.  That is only four times the amount currently used,  the same  change from the 1955 level to now, not a huge jump.  Where will it come from and how do we get there in the next 50 years?  What about those other nations that need to move two orders of magnitude just to reach USA 1960 levels.

There is a really great book by David MacKay FRS, professor of Physics at Cambridge University that begins to open the dialog around a cogent approach to sustainable energy.  Just to get you thinking, if the US were to cut back its current power consumption and life style from 250 KW to the level in the UK lifestyle and consumption of 125 KW, we could replace ALL hydrocarbon fuels by building 525 new 1 Giga Watt Nuclear power plants.  Let us be clear about this. The silly little bits that the “greenies” shout about won’t do it, Cap and Trade will bankrupt industrialized nations and hoping for a new energy source to show up tomorrow is a fantasy.  We and the rest of the world need to get serious about implementing all of the sources, nuclear, solar, wind, tide, wave and and most importantly of all, research into new sources.

You may read MacKay’s book on line or download a pdf of it, at his website “David MacKay Sustainable Energy without the hot air” .  I strongly recommend it.


  1. Thanks very much for your support! I’d like to clarify that “the average UK citizen” uses 125 kWh per day (not 125 kW) and the average American uses 250 kWh per day (not 250 kW). If you want to express these in kW (a very reasonable thing to do!) then 125 kWh per day is roughly 5 kW; 250 kWh per day is roughly 10 kW. (1 kW is exactly 24 kWh per day.) This slightly alters your graph, but doesn’t affect the overall message. All the best! David

  2. You are quite correct. I switched measures mid cycle and did not catch it. I saw your comment yesterday morning and have been wrestling with how best to approach the problem, particularly the 19th Century, with out introducing major fudge factors and assumptions into the earlier stages to portray typical consumption. In one respect, today my available power as a consumer, is limited only by how much I want to spend, the capacity of my local power grid and the the size of automobile engines available. History reflects availability of power, which is why I chose life expectancy as an easily grasped and personal measure as opposed to GDP or infant mortality. I welcome your thoughts.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s


%d bloggers like this: