Emergy, Empower and the Eco-Exergy to Empower Ratio: a Reconciliation of H.T. Odum with Prigogine?

This paper presents the theory behind and the possible uses of the ratio of eco-exergy to empower. This orientor originates from the comparison of S.E. Jrgensens and H.T. Odums approaches to ecosystems theory. The former proposed as orientor the maximization of stored eco-exergy, that is the extension of the thermodynamic function exergy of ecosystems. The latter, the maximization of empower, is the flow of emergy (solar energy directly and indirectly required to obtain a certain item). The use of the ratio of eco-exergy to empower enables one to understand what is the order that the two maximization criteria follow during the evolution of an ecosystem. A possible analogy between the maximization of eco-exergy to empower ratio and the minimization of specific dissipation is discussed. The use of this orientor for the comparison of the same system at different times or of different systems provides a possible holistic measure of the effects of the use of a certain pattern of inputs in a system. This can help comparisons within the framework of life cycle assessment.