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ORIGINS Since before Ratio . Many scientists and analytic philosophers say they are not, and therefore consider some qualitative phenomena like, for instance, Spirituality , and Astrology to be unquantifiable, unanalysable by Scientific Methods , and therefore ungrounded in physical reality. The notion of energy quality therefore has a tendency to be linked with phenomena many scientists consider unquantifiable, or at least incommunicable, and are subsequently dismissed out of hand. SCIENTIFIC DEVELOPMENT Nevertheless, according to Ohta (1994, pp. 90-91) the ranking and scientific analysis of energy quality was first proposed in 1851 by William Thomson under the concept of "availability". This concept was continued in Germany by Z. Rant, who developed it under the title, "die Exergie" (the Exergy ). It was later continued and standardised in Japan . Exergy analysis now forms a common part of many industrial and ecological energy analyses. For example, I.Dincer and Y.A. Cengel (2001, p. 132) state that energy forms of different qualities are now commonly dealt with in Steam Power Engineering industry. Here the "quality index" is the relation of exergy to the energy content (Ibid.). However energy engineers were aware that the notion of heat quality involved the notion of Value - for example A. Thumann wrote, "The essential quality of heat is not the amount but rather its 'value'" (1984, p. 113) - which brings into play the question of Teleology and wider, or ecological-scale goal functions. In an ecological context S.E. Jorgensen and G.Bendoricchio say that exergy is used as a goal function in ecological models, and expresses energy "with a built-in measure of quality like energy" (2001, p. 392). ENERGY QUALITY EVALUATION METHODS There appear to be two main kinds of methodology used for the calculation of energy quality. These can be classed as either receiver or donor methods. One of the main differences that distinguishes these classes is the assumption of whether energy quality can be upgraded in an energy transformation process. Receiver methods: view energy quality as a measure and indicator of the relative ease with which energy converts from one form to another. That is, how much energy is revieved from a transformation or transfer process. For example, A. Grubler {Link without Title} used two types of indicators of energetic quality ''pars pro toto'': the hydrogen/carbon (H/C) ratio, and its inverse, the carbon intensity of energy. Grubler used the latter as an indicator of relative environmental quality. However Ohta says that in multistage industrial conversion systems, such as a hydrogen production system using solar energy, the energy quality is not upgraded (1994, p. 125). Donor methods: view energy quality as a measure of the amount of energy used in an energy transformation, and that goes into sustaining a product or service (H.T.Odum 1975, p.3). That is how much energy is donated to an energy transformation process. These methods are used in ecological physical chemistry, and ecosystem evaluation. From this view, in contrast with that outlined by Ohta, energy quality ''is'' upgraded in the multistage trophic conversions of ecological systems. Here, upgraded energy quality has a greater capacity to feedback and control lower grades of energy quality. Doner methods attempt to understand the ''usefulness'' of an energetic process by quantifying the extent to which higher quality energy controls lower quality energy. ENERGY QUALITY IN PHYSICAL-CHEMICAL SCIENCE (DIRECT ENERGY TRANSFORMATIONS) Constant energy form but variable energy flowT.Ohta suggested that the concept of energy quality may be more intuitive if one consider's examples where the Form Of Energy remains constant but the amount of energy flowing, or transferred is varied. For instance if we consider only the inertial form of energy, then the energy quality of a moving body is higher when it moves with a greater velocity. If we consider only the heat form of energy, then a higher temperature has higher quality. And if we consider only the light form of energy then light with higher frequency has greater quality (Ohta 1994, p. 90). All these differences in energy quality are therefore easily measured with the appropriate scientific instrument. Variable energy form, but constant energy flowThe situation becomes more complex when the form of energy does not remain constant. In this context Ohta formulated the question of energy quality in terms of the conversion of energy of one form into another, that is the transformation of energy. Here, energy quality is defined by the '''relative ease''' with which the energy transforms, from form to form.
Nomenclature: Prior to Ohta's definition above, A.W.Culp produced an energy conversion table describing the different conversions from one energy to another. Culp's treatment made use of a subscript to indicate which energy form is being talked about. Therefore, instead of writing "energy A", like Ohta above, Culp referred to "J''e''", to specify electrical form of energy, where" J" refers to "energy", and the "''e''"subscript refers to electrical form of energy. Culps notation anticipated Scienceman's (1997) later maxim that all energy should be specified as form energy with the appropriate subscript. ENERGY QUALITY IN ECOLOGICAL PHYSICAL CHEMISTRY (DIRECT AND INDIRECT ENERGY TRANSFORMATIONS) Ecological physical chemistry is concerned with the energy conversions where the energy forms and flows are not held constant, and how the form changes over successive indirect transformation steps in an ecological food chain for example. However in developing an accounting system for these energy conversions, theorists found that they needed a reference point where the energy form and average flow is held constant. Constant energy form and constant energy flowIn order to try and make things more easily understood a method is used that is the inverse of Ohta's approach mentioned above. That is, the energy quality determined with reference to a base constant energy form and flow. This base is then contrasted against varying energy forms and flows. This method was employed by Howard T. Odum in the discipline known as Systems Ecology , where the base reference with an averaged constant flow is the solar energy form. This was referred to as the "solar energy transformation ratio" and given the value 1. WIth the subsequent development of the Emergy nomenclature the phrase, "solar energy transformation ratio" was shortened to the term "solar transformity", where "transformity" simply means, "energy transformation ratio" (H.T.Odum 1994). Variable energy form, and variable energy flowIn using this approach H.T.Odum viewd energy quality from the understanding that different energy forms have differents amounts of energy available and can vary and amplify the flows of other energy forms in ways that encourage the further transformation of lower quality energy forms. From this view, the actual flow of calories or joules can decrease as energy is used and dispersed throughout the world. The result of such energy transformation processes can be products, information, services or commodities that are understood to be higher ‘quality’ than the original energy forms. Although the base reference energy form flow is held constant all others are allowed to vary. Energy quality in this sense means that, “the flows become either very concentrated of very high in information content, in either case capable of controlling, Amplifying and causing work that would not be otherwise possible” (H.T.Odum 1994, p. 251). H.T.Odum and colloeages used the generic term "energy transformation ratio", or "transformity" to refer to the energy quality "factor". This ratio contrasts two energy forms that are varied during the flow of a transformation process. ENERGY QUALITY IN BIOPHYSICAL ECONOMICS (INDIRECT ENERGY TRANSFORMATIONS The notion of energy quality was also recognised in the economic sciences. In the context of Biophysical Economics energy quality was measured by the amount of economic output generated per unit of energy input (C.J.Cleveland 2000, p. 1). The estimation of energy quality in an economic context is also associated with Embodied Energy methodologies. Another example of the economic relevance of the energy quality concept is given by Brian Fleay. Fleay says that the "Energy Profit Ratio (EPR) is one measure of energy quality and a pivotal index for assessing the economic performance of fuels. Both the direct and indirect energy inputs embodied in goods and services must be included in the denominator." (2006; p.10) Fley calculates the EPR as the energy output/energy input.
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