Looking at the Limit

The industrial model of civilization requires steadily expanding energy consumption. From an overall perspective, it doesn't really matter where the energy comes from (fossil fuels, hydro, nuclear or renewables), so long as the thermodynamic imperative of increasing the entropy flow into the environment by increasing the exergy throughput of civilization is fulfilled. That's because the underlying driver of civilization is the simple, basic thermodynamic physics of open systems. Even if we get rid of both fossil fuels and nuclear power this framework will still operate. 

This isn't necessarily the result of bad human decisions. The growth imperative that has been necessitated by the Second Law of Thermodynamics is the culprit here. 

As civilization grows, it needs energy for two purposes: to maintain its cumulative asset base (all the stuff we've built so far); and to build new assets to support the expansion of population and activity levels. 

According to Tim Garrett of the University of Utah, just supporting our accumulated asset base requires ~9.7 mW of power per 1990 constant dollar of cumulative Gross World Product (cumulative over at least the last 2000 years). Only once that bar has been met can we devote energy to building out yet more assets. Below that level, presumably, we would fall into something that looks like John Michael Greer's "catabolic collapse". 

Based on Tim Garrett's analysis, here is the situation since 1900. the graph shows the amount of energy spent on maintaining the existing asset base, and its reciprocal: the amount of energy that's left over to use in the growth of civilization. Notice that the "growth energy" has been falling since 1970.


If this assessment is correct, we risk falling into catabolic collapse before 2030 unless we can drastically increase the amount of energy we can generate increases substantially. Energy efficiency increases of a few percent aren't going to be enough. 

You may be looking at the actual limits to growth. 

A press release from the University of Utah talks about Garrett's findings. 

And one last note: Despite all the publicity given to the idea, energy efficiency improvements alone cannot, over the long run, decrease energy use. That's because efficiency improvements simply increase the amount of work that can be performed by the same energy. As that work is translated into money, civilization keeps expanding. It's the Jevons Paradox operating at the level of our entire civilization.

Paul Chefurka
May 27, 2013

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