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 .
