Thermodynamics and resource consumption: Concepts,methodologies, and the case of copper

Abstract

Analysis and minimization of resource consumption is an essential aspect of sustainability. Engineers in this field need to be equipped with concepts and methodologies for assessment and sustainable design of products and processes. Thermodynamics offers these concepts and methodologies. In the current debate on material flows, the throughput of matter and energy is the primary focus. Consumption, however, starts when material and energy is transformed and loses its potential to be useful in further products or processes. On the physical level, this loss of potential utility is well described by entropy production or exergy destruction, two related concepts from thermodynamics. Using these concepts, methodologies for analyzing resource consumption were constructed and have been successfully applied to a large number of processes, products, and services. Here, a very brief introduction to thermodynamics is given to enable the interested reader to understand the underlying concepts and help in the application of thermodynamics to analyze resource consumption. Established measures for resource consumption can be grouped into those approaches which are based on the first law of thermodynamics (the conservation of energy and matter) and those approaches which are based on the second law of thermodynamics (entropy production and the devaluation of energy and matter). A brief summary of the currently used approaches is given and how they relate to the thermodynamic interpretation of resource consumption. Exergy and entropy analysis are introduced as analytical tools and also briefly explained, with recommendations for further self-study to get more familiar with the methodologies. An example, copper making from sulfidic ore concentrates is presented as a case study for the application of entropy analysis, and the results are compared to results from other (exergy) analyses. Finally, an interpretation of entropy production in the context of ecological sustainability and finite resources is offered, based on the finite entropy disposal rate of the earth, which enables the reader to evaluate the meaning of the presented results.