Generalization of the concept of exergy at a national level: A tool for energy planning using Brazil as a case study

Two of the most pressing problems facing humanity are the increasing scarcity of energy resources and the sinister reality of the environmental factor. These problems derive, to a great extent, from the energy-intensive character of modern societies and can by by-passed, by and large, through the definition of energy policies that recognize that energy should be used at the quality level required by the processes rather than energy of excess quality. Responsible energy policies must acknowledge that the demand side is non-homogeneous and that the real energy problem is one of meeting heterogeneous end-use needs with the minimum amount of thermodynamically appropriate energy. The concept of exergy and the generalization of the exergy method of analysis to entire economies seem to add the qualitative dimension that is missed in traditional energy approaches and thus complement conventional techniques adopted in energy planning for dealing with the energy question.;Because food energy--in addition to other energy carriers traditionally accounted for in the formulation of an energy policy--also plays a fundamental role within the energy scenario (the metabolizable energy intake in the form of food the worker consumes seen as the energy contribution of labor to an economy), this research is aimed at approaching the energy problem by centering on (1) the concept of exergy and its application at a national level and (2) the incorporation of the food energy that flows within the borders of a country--entering the economy as primary energy in the form of crops, being converted into secondary energy in the form of food the worker consumes, and finally being converted again into useful energy in the form of human work--into a national energy analysis. A model is built and applied to the Brazilian economy using actual data to test the applicability and policy implications of the new approach. We can thus conclude that an energy policy based on the analytical tool proposed in this study can have broad consequences for the way society is technologically, spatially, politically, and even socially structured, giving an unexpected new dimension to energy planning.