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Using ‘emergy’ analysis to measure eco-village sustainability

28/07/2011

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A survey carried out to measure the sustainability of a Sicilian eco-village suggests that ‘emergy’ analysis produces more comprehensive results than life-cycle or other forms of analysis

As communities strive to meet the challenges of energy efficiency, the need to calculate their sustainability accurately becomes ever greater. However, the variety of contributing factors to such sustainability makes accurate measurements and quantifying in this area difficult. A study carried out in an eco-village in the south east of Sicily by the Department of Physical and Chemical Methodology for Engineering (DMFCI) at the University of Catania could provide the answer. Its application of the ‘emergy’ method of analysis – see Box – indicates that this approach while not an accepted science may hold the key to producing accurate measurements of sustainability.

Emergy analysis was used to quantify the sustainability of the eco-village that is located on an 88-ha farm, which devotes 51 ha to agriculture and 37 ha to woodland, fruit trees and grazing areas. Overall it is a community committed to protection, preservation and restoration of the natural environment. It was for this reason that researchers were interested in applying emergy analysis to give an accurate measure of the sustainability of such a settlement.

Emergy can be defined as the sum of all inputs of energy directly or indirectly required by a process to provide a given product when the inputs are expressed in the same form or type of energy, usually solar energy. The Italian study recognised three distinct energy inputs: local renewable; local non-renewable; and purchased or inputted flows. By dividing the energy inputs of the community along these lines, various insightful calculations could be produced: the town's environmental loading ratio, its emergy yield ratio and, most importantly, its sustainability index. Researchers were than able to apply these indices to evaluate the energy production, the wastewater system and the agricultural practices of the eco-village.

The study showed local renewable energy accounted for 67% of the total output of the village and the sustainability index (SI) was 6.68. A low SI – less than 1 – indicates a highly developed consumer-oriented economies, while a high SI of more than 10 is indicative of economies that have been termed undeveloped. The national average SI in Italy is 0.17, indicating a massive use of non-renewable energy, large imports of purchased energy and materials, and large environmental stress. So the high value of the index for the eco-village could indicate its economy is a model to pursue for a more sustainable development.

 

More information:

Was ist eine Emergy-Analyse?

Die Emergy-Analyse  ist das geistige Produkt des Umweltforschers Howard T. Odum und des Mathematikers David M. Scienceman.Emergy wurde definiert als die Gesamtheit der solar-äquivalenten verfügbaren Energie einer Energieform, die direkt oder indirekt im Rahmen des Entstehungsprozesses eines Produkts oder einer Dienstleistung genutzt wird. Odum wählte Solarenergie, da sie die ultimative Energiequelle ist und es ermöglicht, ungleiche Produkte und Dienstleistungen direkt miteinander zu vergleichen. Danach gelten alle Systeme als Netzwerke von Energieflüssen und die Solarenergie bestimmt den Energiewert der involvierten Ströme und Systeme. Die berücksichtigten Energiezufuhren können sich sowohl auf die Gegenwart und die Vergangenheit beziehen als auch möglicherweise direkt oder indirekt sein. Die Methode stieß auf einige Kritik und wurde als vereinfachend, widersprüchlich, irreführend und ungenau bezeichnet. Viele dieser Kritikpunkte gelten jedoch auch für andere Methoden, die Industrie- und Umweltsysteme analysieren, etwa die Ökobilanzmethode, die kumulative Exergie-Analyse, exergetische Ökobilanzanalyse, Materialfluss-Analyse und ökologischer Fußabdruck.

Weitere Informationen:

„Promise and Problems of Emergy Analysis”:
http://www.che.eng.ohio-state.edu/~bakshi/EcolModel3.pdf pdf [134 KB] Deutsch

"Image source: www.emergysystems.org Deutsch"