The Measure of Unsustainability in Emergy Evaluation

Sustainability is an ideal state, that cannot be “measured” per se. We can instead try to measure the distance from this ideal state. Regarding the use of resources and the emission of residues in the environment, the problem is “extensive”, i.e. a function of the magnitude of the problem (with respect to the size of the system). Humanity is approaching its “limits to growth” and this problem is getting more and more critical. This implies that in Emergy evaluation an analysis of the traditional indicators, such as transformity, ELR, EIR, EYR, %R or ESI, is not sufficient. Unsustainability is related to the use of resources in the N and F categories, not relative to the total Emergy flow or to the R portion, but by themselves: in electricity production the use of more water (in a renewable manner) does not reduce the unsustainability of a thermal plant using fossil fuels. This means that Emergy evaluation should be more based on the consideration of N and F, also using intensive indicators. F and N are then related to the actual use of resources, while the system is mainly passive with respect to R: rain falls on the system; it is not the system that “extracts” rain from the clouds. This has implications on the relationship between emergy evaluation and the concept of carrying capacity.