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BRIEF HISTORY The history of contructing a system of accounts which record the energy flows through our environment can be traced back to the origins of accounting itself. As a distinct method it is often associated with the Physiocrat 's "substance" theory of value (Mirowski 1999, pp. 154-163), and later the agricultural energetics of Serhii Podolinsky, a Ukrainian socialist physician (Martinez-Alier 1990), and the ecological energetics of V.V.Stanchenskii (Weiner 2000, pp. 70-71, 78-82). However the main methods of embodied energy accounting as they are used today, grew out of Wassily Leontief 's Input-output Model and are called ''Input-Output Embodied Energy analysis''. Leontief's input-output model was in turn an adaptation of the neo-classical theory of general equilibrium with application to, "the empirical study of the quantitative interdependence between interrelated economic activities" (Leontief 1966, p. 134). According to Tennenbaum (1998), Leontief's Input-Output method was adapted to embodied energy analysis by Hannon (1973) to describe ecosystem energy flows. Hannon’s adaptation tabulated the total direct and indirect energy requirements (the ‘energy intensity’) for each output made by the system. The total amount of energies, direct and indirect, for the entire amount of production was called the ‘embodied energy’. ERROR IN EMBODIED ENERGY METHODOLOGIES Different methodologies use different scales of data to calculate energy embodied in products and services of nature and human civilization. International consensus on the appropriateness of data scales and methodologies is pending. This difficulty can afford a wide ranges in embodied energy values for any given material. In the absence of a comprehensive global embodied energy public dynamic database, embodied energy calculations may omit important data on, for example, the rural road/highway construction and maintenance needed to move a product, human marketing, advertising, catering services, non-human serivices and the like. Such omissions can be a source of significant methdological error in embodied energy estimations. Without an estimation and declaration of the embodied energy error, it is difficult to calibrate the , and so the Value of any given material, process or service to environmental and human economic processes. CLASSIFICATION OF EMBODIED ENERGY METHODOLOGIES There appear to be three main differences in contemporary embodied energy methodologies. Following Tennenbaum (1988) these may be identified as ‘ Anthropocentric ’ and ‘ Capitalcentric ’, with a third identified as ‘ Ecocentric ’. According to Tennenbaum, the difference in methodologies is determined by how they treat, and where they attribute energy depreciation in a network of ecological system energy flows. In all the methods, depreciation is taken away from the production process under consideration and reassigned elsewhere in the total system. What characterises a method is where they assign this energetic loss. According to Scienceman (1987), the principle point of difference is whether embodied energy is partitioned at work intersections and apportioned among pathways. Anthropocentric embodied energy analysisAnthropocentric embodied energy analysis is interested in what energy goes to supporting a consumer, and so all energy depreciation is assigned to the final demand of consumer but not to storages of ‘assets’ or ‘capital stocks’. It is associated with Hannon’s work. There is no requirement that energy must be expressed as one Energy Form Or Quality . Capitalcentric embodied energy analysisCapitalcentric embodied energy analysis is interested to know what supports assets, energy depreciation is therefore assigned to storages of ‘assets’ or ‘capital stocks’, but not to final demand. This method is associated with Herendeen's and Costanza's works, where embodied energy is apportioned among pathways and partitioned at work intersections, and is therefore additive just like first law heat energy. As with the anthropocentric view, there is no requirement that energy must be expressed as one Energy Form Or Quality . Ecocentric embodied energy analysis: EmergyIn ecocentric embodied energy analysis, depreciation is assigned to a unit of production, that is, assigned to both storages of ‘assets’ or ‘capital stocks’, and to final demand. This method is associated with H.T.Odum's works, where embodied energy is not apportioned among pathways and is therefore not additive just like first law heat energy. Energy is only partitioned at work intersections that are diverging, flexible and high-quality energies that feed back (1994, p. 264). Odum's interpretation was informed by similar notions of feed back as used in electronic circuits.
Dr.D.M.Scienceman coined the term ' ''there is a requirement that energy must be expressed in one Energy Form Or Quality ''. Non-emergy approaches most often evaluate only nonrenewable resources, depending on what human technologies are able to extract from them (user-side quality). The Energy Systems Language is used to help make emergy algorithms transparent. REFERENCES
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