SUSTAINABILITY OF ENERGY SYSTEMS AND SCIENTIFIC LITERACY: THE CONCEPTS OF EXERGY AND EMERGY

Facing complex social and environmental problems require interdisciplinary knowledge and approaches ranging from hard science to Economics, even involving ethical issues. In this context, the assessment of suitable evaluation procedures for planning and managing renewable and sustainable energy systems is strongly needed. The aim of the contribution is at addressing the university students need as Physics cultural background for a scientific approach to environmental as well as social problems. In particular, the concepts of Exergy and Emergy are addressed as effective indicators of the real sustainability of energy supply, and some tutorial examples are presented of exergy- or emergy-based analyses of energy systems. Exergy is a thermodynamical quantity which quantifies the connection between a system and its environment as the actual work available from a certain energy flow. On the other hand, emergy (from "embodied energy") quantifies the "real" wealth and standard of living, accounting for how much energy is actually embedded in a product or service in terms of the energy used to "build" it. Furthermore, emergy per money unit is the emergy for the generation of one unit of economic product (in currency), so expressing money transfers in emergy units. In this way, an energy flow process analysis can include monetary transfers, directly related to the purchased emergy. By using these indicators, social, economic and environmental issues may find place in an analytical quantitative approach for the planning of energy systems, indicationg how their knowledge is needed by decision-makers (technologists, politicians, econonomists) at any level.