Modeling the Energetic and Exergetic Self-Sustainability of Societies With Different Structures

Abstract

The paper examines global energy and exergy flows in various models of organized human societies: from primitive tribal organizations to teocratic/aristocratic societies, to the present industrial (and post-industrial) society, to possible future highly “robotized” or “central control” social organizations. The analysis focuses on the very general chain of technological processes connected to the extraction, conversion, distribution and final use of the real energetic content of natural resources (i.e., their exergy): the biological food chain is also considered, albeit in a very simplified and “humankind” sense. It is argued that, to sustain this chain of processes, it is necessary to use a substantial portion of the final-use energy flow, and to employ a large portion of the total work force sustained by this end-use energy. It is shown that if these quantities can be related to the total exergy flow rate (from the source) and to the total available work force, then this functional relationship takes different forms in different types of society. The procedure is very general: each type of societal organization is reduced to a simple model for which energy and exergy flow diagrams are calculated, under certain well-defined assumptions, which restrain both the exchanges among the functional “groups” which constitute the model, and the exchanges with the environment. It is argued that not all societies are unconditionally self-sustained, and that certain size and technology-related restrictions apply to virtually all types of societal organizations examined here. These restrictions limit in general the distribution of the active workforce among different productive sectors; this distribution cannot be arbitrarily assigned, but depends quantitatively on the technological level of the chain of processes connected with energy extraction, transformation, distribution, and use. The results can be quantified using some assumptions/projections about energy consumption levels for different stages of technological development which are available in the literature; the procedure is applied to some models of primitive and pre-industrial societies, to the present industrial/post-industrial society, and to a hypothetical model of a future, high-technology society. No attempt has been made to study transient behavior (“evolution” or “decay” of a certain type of society), nor to relate quantitatively the steady-state case to resource conservation and environmental protection. For most of the cases examined here, neither resource scarcity nor finite biosphere capacity were considered as constraints.