Working Paper
This paper argues that thermodynamics offers a means of accounting both for resources and wastes in a systematic and uniform way. Unfortunately, the proposed measure has been called by several different names, including available work, availability, exergy and essergy by different authors, in different countries and for different purposes. Another closely related measure has been called potential entropy, or physical information (pi potential). At bottom, however, exergy is a measure of distance from thermodynamic equilibrium. It is not a conserved quantity (like energy) but it is possible to construct an exergy balance for any energy or materials transformation process, accounting for inputs, process losses, useful products and wastes.
The essential unity underlying the various independent definitions and research efforts has not been recognised until recently. Most of the basic data has been compiled, and has been published in the scientific literature. Unfortunately, because it was done mainly in the context of design optimisation in mechanical, chemical and metallurgical engineering, the relevant publications are not very accessible to other disciplines.
The new feature of the present work is to extend the applications of exergy analysis into the realm of resource and waste accounting, and to present the results in an integrated analytical framework, namely life cycle analysis (LCA). To do this for a non-specialist audience requires considerable background explanation. This is done in Part I (sections 1 through 6). Applications and examples are discussed in subsequent sections (part II). The paper concludes that the proposed measure is indeed feasible for general statistical use, both as a measure of resource stocks and flows, and as a measure of waste emissions and potential for causing environmental harm.
