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What is Exergoecology?

Exergoecology is the application of the exergy analysis in the evaluation of natural fluxes and resources on earth. The consumption of natural resources implies destruction of organized systems and dispersion, which is in fact generation of entropy or exergy destruction. This is why the exergy analysis can describe perfectly the degradation of natural capital.

The thermodynamic value of a natural resource could be defined as the minimum work (exergy) needed to produce it with a specific composition and concentration from common materials or reference substances in the Reference Environment.

Therefore exergy can account for the concrete physical characteristics which make natural resources valuable: a particular composition, which differenciates them from the surrounding environment, and a distribution which places them in a specific concentration. Hence, quantifying natural capital in terms of exergy is more rigorous, coherent and comprehensive than with mass or money.   Read more...

The Reference Environment

The exergy of a system gives an idea of its evolution potential for not being in thermodynamic equilibrium with the environment, or what is the same, for not being in a dead state related to the Reference Environment (R.E.). Therefore, for calculating the exergy of any natural resource, a R.E. should be defined. This R.E. must be determined by the natural environment and can be assimilated to a thermodynamically dead planet where all materials have reacted, dispersed and mixed.

The determination of the natural capital exergy is necessarily linked to the definition and thermodynamic properties of the R.E. Hence the importance of an appropriate selection of a R.E. for evaluating natural resources. Read more about Szargut's R.E.


Exergy Costs

Exergy accounts for a minimum. However, the real processes designed by man are far from the ideal conditions for reversibility and the energy requirements to obtain a resource are always greater than those dictated by the Second Law. For this reason, we cannot evaluate natural resources solely in terms of reversible processes since this would ignore technological limits, which are much more costly for man from the physical point of view. Therefore, we must include the real physical unit costs in the thermodynamic evaluation of resources.

The exergy costs are defined as the relationship between the energy invested in the real process of obtaining the resource and the minimum energy required if the process were reversible. They measure the number of exergy units needed to obtain one unit of exergy of the product.

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Thermoecological Costs

Industrial processes have an unfavourable influence upon the natural environment. These unfavourable effects can be divided into two groups: depletion of limited non-renewable resources and rejection of harmful substances. The depletion of non-renewable resources should be minimised to keep them for future humankind. Exergy can be applied as a measure of the quality of natural resources. The influence of human activities on the depletion of natural resources can be evaluated by means of the cumulative exergy calculus.

The thermo-ecological cost is defined as the cumulative consumption of non-renewable exergy connected with the fabrication of a particular product with inclusion of additional consumption resulting from the necessity of compensation of environmental losses caused by rejection of harmful substances to the environment. Moreover, the index of thermo-ecological cost should take into account the total life-time of the considered product or system.
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Physical Hydronomics

The water cycle is governed by the Thermodynamic laws. Therefore Thermodynamics and more specifically Exergoecology,  could help to build a solid cost structure based strictly on Physics and far removed from price policies or subjectivities.

Any type of degradation of water bodies along their rivers, lakes, etc. could then be quantified. Moreover, the physical information of the resource can be unified into universal units (energy units), and the monetary conversion of exergy costs is automatic through conventional energy prices. This new research area named “Physical Hydronomics”, could constitute a guide to assess environmental costs included in the European Water Framework Directive (WFD).

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Created by aliciavd
Last modified 2008-10-14 04:14 PM
 

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