Ecological Cumulative Exergy Consumption and Extended Exergy Accounting: Comparison and Challenges in Evaluating Technological and Biological Systems

To evaluate the resource required by energy systems and by technological production systems in general, exergy has emerged as an effective concept and exergy analysis is increasingly being adopted as and effective tool. In addition, while dealing with complex, multi-component, energy systems with both, direct and indirect exergy consumptions required for obtaining a certain product flow, an exergy cost accounting has to be implemented. Furthermore, the true primary exergy resources, directly and indirectly available for the production system, have to be considered when the goal is to address the impact, or the sustainability, of the production system itself. A variety of approaches have been developed in the recent past, such as the Ecological Cumulative Exergy Consumption method and the Extended Exergy Accounting method. In the present paper, those two approaches are compared and commented, highlighting similarities and limitations and assessing their applicability to technological and biological systems .