Emergy analysis is useful for evaluating the resource utilization and environmental performance of industrial systems. However, emergy analysis in its current state can produce erroneous results when it is applied to systems with feedback structure. It is shown that traditional emergy algebra, if not applied properly, can cause violations of the tenet of total inheritance, which is one of the core notions in emergy theory. To overcome this deficiency, this paper proposes a new concept, called virtual emergy flow, for calculating the emergy of feedback structures. The utility of the virtual emergy flow concept is illustrated by the emergy analyses of two different types of feedback structures commonly found in chemical process systems as well as by a case study based on a power and methanol multiproduct system.