The Way Forward in Quantifying Extended Exergy Efficiency

Abstract

Extended exergy accounting (EEA) is a methodology which estimates the extended exergy cost (EEC) of a product or a service or the extended exergy efficiency (EEE) of a country or economic sector taking into account materials, energy, labour, capital, and environmental impact. The use of EEA results for policy or planning purposes has been hampered by: (1) the lack of data to quantify the EEC of most of the inputs, making it almost impossible to quantify the EEC of a product or service and (2) the lack of a conceptual framework to quantify in a consistent way the exergy of labour and capital. In this paper, we make a review of past studies to identify, synthesize, and discuss the different EEA methods. We identified 3 different EEA methods, that we further compare using the Portuguese Agriculture, Forestry, and Fishery (AFF) sector from 2000 to 2012. The equivalent exergies of labour and capital estimated for the AFF sector vary widely among the three EEA methodologies. We propose and test a new EEA methodology to estimate EEE which accounts for these fluxes in a more restricted scope but more consistently and that includes the Environmental Benefit (EB) that represents the capability of the forestry to capture carbon dioxide. Results show that the EEE of the Portuguese AFF sector has increased by 32% from 2000 to 2012.

The Exergy Footprint as a Sustainability Indicator: An Application to the Neanderthal–Sapiens Competition in the Late Pleistocene

“…For obvious reasons, this paradigm is known as "extended exergy analysis", or EEA. Previous studies on its application [22,26,[54][55][56] have provided some interesting results: EEA leads to the calculation of the total amount of primary exergy needed to produce a material or immaterial commodity [22,26,57], i.e., to a thermodynamic cost index. More recently, it has been shown that the application of EEA to a society provides a measure of its "exergy footprint", i.e., of its global resource consumption, which is obviously an indicator of the thermodynamic sustainability of the "system society" (in more proper terms, an indicator of the degree of its unsustainability).…”

Energy Efficiency of Biorefinery Schemes Using Sugarcane Bagasse as Raw Material

“…From thermodynamics, exergy is defined as the maximum amount of work that can be generated by a system (including mass and energy flows) once a thermodynamic equilibrium with the environment is achieved [21][22][23][24]. Compared to the energy, the exergy of a system is not conserved [25]. This fact is because of the entropy changes that are caused by physical and chemical conversions that are associated with irreversible processes.…”