Industrial Ecology for a Sustainable Future Royal Institute of Technology Stockholm 12 - 15 June 2005

Here, an implementation of entropy generation as a measure forresource consumption within the framework of LCA is proposed. Entropygeneration is chosen over other measures (such as exergy) mainly for conceptualreasons, and for reasons of scientific stringency and conciseness (see below).The implementation is facilitated via one of the widely used software tools(Umberto), which can be extended to accommodate thermodynamic data for thematerial and energy flows. Thus the same computer model that is used for theLCA can be used for entropy analysis, significantly saving time and effort. Atthe example of copper production, it will be shown that the use of entropyanalysis is straightforward and relies only on commonly availablethermodynamic data (in addition to the detailed life cycle inventory).Implementation into a standard LCA tool opens the way for further applicationsof this method, even for LCA practitioners with little expertise inthermodynamic analysis. Background: Life Cycle Assessment (LCA) is a tool for environmentaldecision support with a strong accentuation of material and energy flows. Theemphasis lies on analysing flows at the interface between the analysed systemand its environment, while the actual transformations within the system are nottaken account of. LCA thus delivers valuable insights into the problemsgenerated by industrial processes, which usually appear at the interface betweenthe technosphere and the environment, but it is only of little help in findingviable solutions to these problems, which must be sought within thetechnosphere. One of the shortcomings of LCA in this respect is the lack of acommon measure for assessing the consumption of resources. Resourceconsumption happens within the technosphere and its analysis along the lifecycle of products can help considerably in finding alternatives with a lesserenvironmental impact.Consumption is usually the result of physical and chemical transformations andthe accompanying degradation. It is thus straightforward to search for a commonmeasure of consumption in the realm of thermodynamics. The two mostpromising candidates thus far are exergy loss [1, 2, 3] and entropy production[4]. While they are closely related thermodynamically, they still differconsiderably in their fundamental definition. The exergy concept draws much ofits appeal from the notion of “useful energy”, which, in theory, can be extractedfrom the system under consideration when it is brought into equilibrium with its