Medieval society EROEI

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sofistek's picture
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Medieval society EROEI

In this chapter, Chris states:

If, instead, these people were able to produce just 1.2 calories for every 1 calorie expended, then they’d have the exact energy balance that existed in medieval times. This skinny 20% surplus allotment of energy is sufficient to allow rich hierarchies to form, job specializations to develop, and large works of architecture to be built.

This implies an EROEI of 1.2:1, for medieval societies.

Another fellow of the Post Carbon Institute, Richard Heinberg, in his recent essay, Searching for a Miracle", states that the hunter-gatherer society is perhaps the simplest model for a society and operated on an EROEI of 10:1. He suggests, therefore, that an EROEI of 10:1 may be the minimum that is needed for a society. It would seem that complex societies require an EROEI of greater than 10:1.

So how can both Richard's and Chris's comments be reconciled? Perhaps they aren't both using the same measurement.

For me, it seems unlikely that any society could exist on an EROEI of 1.2:1, and I wonder if Chris inadvertently put that decimal point in, although the 20% figure seems to confirm it. I assume the energy sources in medieval times would have been food, wood, wind and hydro, of sorts. If the people producing and distributing that energy consumed 83% of it in just proding it, then only 17% of the energy produced, has to support the rest of society, including all those not involved in energy production and all of the lifestyles of those involved in energy production, when they are not producing energy.

I'd be grateful for any thoughts on this and, if Chris could expand on his statement, with references, that would be even better.

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