Insights · August 3rd, 2011

Yesterday I discovered a really terrific website, a blog called Do the Math, by UCSD professor Tom Murphy. He is a physicist and mathematician, who began wondering if commonly held assumptions mostly about the future could be true when subjected to math. For example, in this blog and a related one he wrote earlier Professor Murphy asks if economic growth forever is possible. It has been true in the U.S. since 1650, and virtually all economic models, political reasoning, and personal hopes assume that we can just keep growing as we have. Tom notes the correlation between economic growth and the 2.9% annual growth in energy consumption in the U.S. for the last 360 years. Economic growth has been connected to energy growth. No mystery there.

Unless we can decouple economic growth from increasing energy consumption the merry-go-round will come to a stop, because energy growth cannot continue. Why? Because anything that grows at a regular annual percentage rate enters the realm of exponential growth, where things double over time. Remember the old calculation for the doubling rate? It is basically 70 divided by the percent growth rate. So, if U.S. energy consumption grows at 2.9%, then our energy use will double in 24 years. In 48 years, about 2060, we’d be using four times as much energy as today. Now factor in world economic growth (remember China) and world growth in energy consumption. In his clever blog Professor Murphy proves that if the doubling rates were to continue like this (he actually lowers the annual growth rate in energy to 2.3% so that each doubling takes 100 years) the earth would be producing, and using, more energy than the sun in 1400 years. Peter summarizes:

Let me restate that important point. No matter what the technology, a sustained 2.3% energy growth rate would require us to produce as much energy as the entire sun within 1400 years. A word of warning: that power plant is going to run a little warm. Thermodynamics require that if we generated sun-comparable power on Earth, the surface of the Earth—being smaller than that of the sun—would have to be hotter than the surface of the sun!

1400 years sounds like a long time, but limits of technology will be reached long before that. You can use less energy by increasing the efficiency of cars, buildings, computers and so on but only until they are 100% efficient and then no more (well, you can’t actually get to 100%). Thus increases in the use of energy become “impossible within conceivable time frames” (less than a couple of hundred years). Implication: because economic growth, which everyone wishes for right now, is linked to growth in energy use and that cannot continue, a new economic model that enables prosperity without growth is on the horizon, or had better be.

His blog yesterday, by they way, explored whether it would be mathematically possible to build enough batteries to provide sufficient back-up power to run the U.S. if we were to convert to a solar and wind energy economy. His conclusion is no, not enough raw materials on planet earth, either for lead-acid or for variations on lithium-ion batteries or both.

Check it out.

(Coincidently I will be doing a lunch keynote for the Association for Corporate Growth in Seattle tomorrow, August 4, 2011. What should I tell them?)

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Glen Hiemstra is a futurist speaker, author, consultant, blogger, internet video producer and Founder of To arrange for a speech contact

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