An exergy analysis of the Brazilian economy: From energy production to final energy use

Abstract

The concept of exergy is applied to a national economy as a tool for energy planning. Conversions and utilizations of energy carriers in Brazil are described in terms of both energy and exergy. The energy analysis of the Brazilian economy shows that the overall first-law efficiency of the country's energy system is 32.4%, while the exergy analysis shows that the overall second-law efficiency is only 22.8%. Expressed in a different way, the exergy approach uncovers that the efficiency with which the Brazilian economy uses its energy resources is only about two-thirds of that manifested by the traditional heat-balance approach. The exergy approach not only reveals the existence of an inadequate match between the quality of the energy carriers supplied to end users and the quality required by final consumers to perform their energy services, but also indicates that there is room for improvement in the nations's energy conversion and utilization systems. These facts imply that the Brazilian economy has a significant potential for energy savings and, consequently, great promise for reducing the environmental burden associated with energy production and use, without compromising the quality of the services demanded by end users or else for providing greater services with the same energy.