Exergy and Demography: Present Scenarios and Future Projections

The study presented in this paper is intended to be a contribution to the practical implementation of the “sustainability” concept, often misunderstood at times and incorrectly applied. The first sections describe a systematic procedure for a rigorous definition of “sustainability” and of “sustainable development” based on thermodynamics. A concept tightly connected with “sustainability” is “resource thriftiness”, i.e., the reduction in the anthropic extraction of irreplaceable supplies of fossil ores and fuels contained in the Earth’ crust and the reduction in the load posed on the environment by discharges, collectively referred to as “environmental conservation”: this is another concept that must be embedded in the definition of sustainability. An environmentally friendly society ought to concentrate on minimising such consumption by implementing an efficient and rational conversion of primary resources to final commodities while maintaining acceptable life standards. A thermodynamics-based approach can help identify the boundaries of the “sustainable region”: if sustainable development depends on a balance between primary input and final consumption, the internal allocation of the latter among citizens becomes a relevant parameter. The study presented in this paper introduces a direct link between demographics and pro capite final exergy use, showing how the age distribution of a society strongly impacts primary consumption. The paper presents some considerations about the quantitative link between the so-called “demographic pyramids” and the exergy budget of a country, with specific examples based on currently available data.