On the Second-Law inconsistency of Emergy Analysis

The paper argues against the claim made by Emergy Analysts that emergy is an exergy-based procedure. Both Emergy- and Exergy Analysis employ space- and time integrated energy input/output models to quantitatively assess the resource consumption of physical systems: the issue at stake is whether Emergy is embodied energy or embodied exergy. Although the compatibility of Exergy- and Emergy accounting procedures, the significance of the peculiar Emergy Algebra, and some cost-allocation issues have been studied in detail, a final agreement could not be reached, so that some doubt exists about the degree of compatibility of the two methods. The present paper shows that the definitions and the procedures employed in Emergy Analysis are in fact First Law-based, and that they neglect or misrepresent Second Law issues. This conclusion is reached by carefully reviewing and critically analyzing a series of general and specific procedures contained in the original Odum books and in some of the most representative publications by Emergy analysts.