PROCEEDINGS OF ECOS 2023 - THE 36 TH INTERNATIONAL CONFERENCE ON EFFICIENCY, COST, OPTIMIZATION, SIMULATION AND ENVIRONMENTAL IMPACT OF ENERGY SYSTEMS 25-30 JUNE, 2023, LAS PALMAS DE GRAN CANARIA, SPAIN The future of Thermoeconomics: from industrial cost minimization toward cumulative resources accounting and sustainability assessment Mauro Reini a and Melchiorre Casisi b a Dept. of Engineering and Architecture, University of Trieste, Italy, reini@units.it b Polytechnic Dept. of Engineering and Architecture, University of Udine, Italy, melchiorre.casisi@uniud.it Abstract: Thermoeconomics has been developed with the main object of first identifying, and then reducing the costs of the energy produced by industrial power plants. More recently, the same approach formalized in the Exergy Cost Theory has been recognized as a useful tool also in a wider field, like industrial symbiosis and sustainability assesment. To do this, exergy supply chains have been tracked backward and backward, to include in the primary resource consumption a more and more complete inventory of the indirect consumption. In Authors’ opinion, the future of Thermoeconomics is to go on in this directions. If a very complete inventory of all indirect consumption were obtained, the sustainability assessment of a production process could be performed (at least in principle) by applying the idea that the lower its consumption (direct and indirect) of scarce primary resources, the more sustainable a production process is. In this paper, the idea of the Thermoeconomic Environment (TEE) is summarized, to highlight as it is a consistent ultimate boundary of the exergy cost accounting, where the origin of the exergy supply chains can be properly placed. Then, the frame of the TEE is used to discuss some possible options for obtaining a more complete inventory of all indirect consumption, and to outline possible perspective connections with some relevant environmental models, coming from Biology, Dynamic of Populations, or Climatology. Keywords: Thermoeconomics; Exergy Replacement Cost; Exergy equivalent of capital and labour; Exergy costs of bioproducts; Sustainability. 1. Introduction Thermoeconomics has been developed with the main object of first identifying, and then reducing the costs of the energy produced by industrial power plants (see, for instance [1-3]). From the beginning, the very fundamental ideas of this approach were: x All Fuels (local resource consumed by a process, or by a component) have to be evaluated in term of the exergy of the streams entering (or leaving) the considered control volume, and the same for the Products (goods or commodities locally obtained for the usage in a different part of the system, or for the outside). x For a process, or a component, the exergy cost of the Products have to be calculated taking all Fuels into account, with their specific exergy costs, disregarding if some Fuels come from the upstream, or the downstream part of the production chain. x The total cost of the Fuels is allocated on the Products. If a process, or a component, obtains more than one Product at the same time, the total cost is allocated in proportion to the exergy content of each Product. As a consequence of the previous assumptions, the exergy cost is a conservative magnitude, and the exergy costs obtained by aggregating contiguous control volumes, are consistent with the exergy costs obtained by the previous, smaller, control volumes. These are similar to the properties of the monetary cost, in a closed economy without profit. This analogy is at the basis of the name Thermoeconomics. From the very beginning of Thermoeconomics, the problem arose of including in the exergy cost balance also the resources consumed for owning, operating and maintaining the hardware of the system, i.e. the capital costs of all its parts. The first solution found was consistent with the objective of limiting the Thermoeconomic Analysis to the control volume of a power plant, converting all input flows of resource in terms of monetary costs, using the known values of the unit costs of the energy carriers at the control volume frontier. 48 https://doi.org/10.52202/069564-0006