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Exergy Budget, Sustainability And Economic Indicators For The Italian System From 2007 To 2017-A Critical Analysis.
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1  University of Rome "Sapienza"

Published: 12 September 2020 by MDPI in The First World Energies Forum session Exergy (registering DOI)

In the recent past, several examples of the application of Exergy Analysis (ExA) to entire Countries have been published, and it can be fairly said that -while the goals of the individual Authors were completely consistent- the results, the conclusions and the recommendations seem to diverge. There are several contingent reasons for this, but the underlying problem is that a purely thermodynamic analysis does not represent the complex influence that monetary, social, political and technological factors have on the purely “material” or “energetic” streams. Clearly, ExA represents a substantial improvement with respect to the “Material and Energy Balance Reports” published annually by most industrialized Countries, because the exergy flow diagram unequivocally demonstrates how and at what penalty the primary exergy inflow (fossil fuels, renewables, ores, harvested food and feed)is transformed into final energy, such as diesel fuel, electricity or other commodities. The issue here is that the so-called Externalities (Capital, Labour and Environmental Effects) are, in spite of some opinion to the contrary, completely left out of the picture. It turns out though that ExA can be extended by including the exergy equivalents of the externalities: the theory is called Extended Exergy Accounting (EEA) as a reminder of the inclusion of monetary, labour and environmental “exergy costs” in the global budget. Scope of the study presented in this paper is twofold: first, to discuss in a formally structured fashion a general procedure for performing the EEA of a “System Country”; second, to inspect the results to identify possible correlations between the “exergy efficiency” of a Country -i.e., its ability to exploit the incoming exergy flux with the minimum amount of losses (material, energy waste and irreversible exergy destruction)- and some of the most popular indicators used to assess the “degree of sustainability” of a system, bearing in mind a time frame of ten years (2007-2017).As an efficiency indicator we use the Exergy Footprint, a measure of the global primary exergy consumption of a system, which turns out to be also a very useful indicator of the “degree of unsustainability” of a Country. Our results confirm that the Gross National Product, already criticized for not representing the reality of the economy of a Country, is very weakly -if ever- correlated with the EF in the decade of observation. Other indicators display different degrees of correlation with the EF, and the reasons are critically analyzed.

Keywords: Exergy Analysis; Exergy Footprint; Sustainability Indicators; Extended Exergy Accounting;