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3 ALLEGRA_6:rivista21x27.qxd 29/07/11 09:38 Pagina 69 Analisi emergetica per lariqualificazioneterritoriale: il caso studio della Provincia di Catania parole chiave: entropia, valutazione, emergia, territorio La questione dell’inarrestabile incremento dell’entropia A partire dagli anni Ottanta si sviluppa l’analisi emerge- totale, enunciato dal secondo principio della termodi- tica per iniziativa dell’ecologo Howard Odum. Essa quan- namica, e del depauperamento delle fonti non rinnova- tifica le risorse naturali rinnovabili e non, che sono con- bili di energia, ineluttabile conseguenza di ogni proces- sumate per realizzare merci e servizi, adottando un’uni- so di trasformazione urbana, nonché di qualsiasi attività ca, comprensibile unità di misura: l’energia solare, pri- economica, è un tema di acceso dibattito sin dalla “crisi migenia generatrice di ogni attività ecosistemica, impie- energetica” degli anni Settanta. Essa ha posto in eviden- gata, in modo diretto e indiretto, per creare tali risorse. za la necessità di ricorrere a strumenti valutativi basati Nel presente saggio, dopo una sintetica esposizione dei sul calcolo energetico prima che monetario, in grado di principi e delle regole fondamentali di questa metodo- interpretare esaustivamente le istanze ambientali ed eco- logia applicata al territorio, si illustrerà il caso studio del- 1. INTRODUZIONE
dalla dottrina marxiana viene sostanzialmente eluso dallascuola neoclassica: se Quesnay3 rappresenta l’ideale siste- Nel 1972 lo studioso americano Commoner1 denuncia l’al- ma produttivo del regno francese con un circuito chiuso il terazione degli equilibri ecologici, basati sui trasferimenti cui surplus coincide con i doni offerti generosamente dal- ciclici delle sostanze nutritive negli ecosistemi terrestri, a la terra, sollecitata dal lavoro umano, e Marx ritiene la natu- causa dell’attuale sistema economico. Egli evidenzia l’ele- ra “fonte dei valori d’uso”4, il pensiero marginalista, nella sua vata efficienza dei processi naturali nella biosfera, la quale formulazione più ortodossa, ricerca la massimizzazione del è caratterizzata da un ricambio continuo, in contrapposi- piacere individuale nel consumo di un’opportuna combi- zione alla creazione antropica, unidirezionale, di merci e nazione di beni “scarsi” in contrapposizione alle risorse rifiuti a mezzo natura che gonfia la “tecnosfera”, definita naturali gratuite perché “abbondanti”5. Da ciò si deduce da Nebbia (2002)2 come “pezzo di pianeta occupato dalle che l’applicazione dei criteri di valutazione monetaria dei beni ambientali, elaborati nel quadro di impostazione neo- Dall’excursus storico delle teorie economiche si evince che classica, comprensibile se finalizzata a determinare gli il ruolo primario assegnato alla natura dalla fisiocrazia e indennizzi da corrispondere ai singoli o alla collettività a 4 Georgescu Roegen N. (1982), p. 31.
3 ALLEGRA_6:rivista21x27.qxd 29/07/11 09:38 Pagina 82 Tabella 4 - Analisi emergetica delle opere di urbanizzazione primaria nel piano di Zona di Librino
STRADE E PARCHEGGI
Strade (lunghezza: 17.200 ml;
Parcheggi (quantità: 2,5 mq/ab)
Canalette
Marciapiedi
Pozzetti pali illuminazione
RETE FOGNARIA
Acque bianche
Acque nere
RETE IDRICA
Acquedotto
Pozzetti di ispezione
Caditoia
Totale emergia
Emergia per abitante (68.184 ab.)
R Bijorklund J., Geber U., Rydberg T. (2000), Emergy analysis of municipal wastewater treatment and generation of electricity by digestion of sewage
sludge, in “Resources, conservation amd recycling” vol. 31 n. 4, pp. 293-316.
S Pulselli R. M., Simoncini E., Pulselli F., Bastianoni S. (2007), Emergy analysis of building manufacturing, maintenance and use: Em-building indice
to evaluate housing sustainability, in “Energy and buildings” n. 39, pp. 620-628.
EMERGY ANALYSIS FOR REGIONAL DEVELOPMENT.
system, which is characterised by a one-way production THE PROVINCE OF CATANIA CASE-STUDY
In the 1970s the American biologist, Commoner, It can be inferred from a historical overview of economic reported a change in the earth’s ecological balance, due theories that the primary role assigned to nature by to cyclical movements of nutritional substances in the Physiocracy and Marxist doctrine is basically ignored by earth’s ecosystems, resulting from the current economic the Neoclassical school which, in its most orthodox 3 ALLEGRA_6:rivista21x27.qxd 29/07/11 09:38 Pagina 83 Analisi emergetica per la riqualificazione territoriale: il caso studio della Provincia di Catania form, looks to the consumption of a suitable energy, which is a more diluted source, to make a joule combination of ‘scanty’ goods, rather than ‘abundant’, of electrical energy. Therefore, H. Odum suggested free natural resources, to maximise individual pleasure. referring them to just one single measurement unit, From this it can be deduced that the application of solar energy, which is at the basis of every activity in the ecosystems. ‘Solar emergy’ (from energy memory), or understandable if used to determine compensation more concisely emergy, represents solar energy that has to individuals or the community for damage suffered, fuelled the chain of operations performed by nature for example by pollution, but risks revealing ‘all the and man to create a particular service or article, and is artificiality of simulated markets’, becoming a ‘useless therefore incorporated into economic processes as well complication’ (Bresso, 1996), if used to evaluate as natural ones. Its unit of measurement is the solar emergy joule (sej). To translate any one type of energy In the sector of scientific estimation, it has been into solar energy a conversion factor is used, ‘solar ascertained that when plans and projects with potential transformity’, or simply transformity. For any given environmental impact must be chosen, it is necessary product this is the emergy necessary to achieve it as to develop suitable decisional support methods, in regards its energy (J) or mass (g) content; so its order to overcome single-criteria monetary analyses, measurement unit is the sej/J o sej/g. Transformity is a such as Cost-benefit analysis, which are often judged to measurement of the efficiency (or sustainability) and be biased, but also to prevent multi-criteria analysis quality of systems: when results are equal it is inferior from seeming, or being, ‘soulless’, a kind of manic, in less dissipative systems, due to the maximum power analytical calculation for its own sake (Rizzo, 2000). principle. In general, when outputs are different the onewith a greater transformity has a superior hierarchical As regards EIA (Environmental Impact Assessment) and level because more natural capital and time were ESA (Strategic Environmental Assessment) tools, the state of the art reports and environmental impactstudies, that have so far been prepared, underline some In the Eighties, H. Odum created a method which he critical points: in particular, it has been ascertained that called ‘Emergy analysis’ which is based on calculating in at the expense of the quantitative, a multitude of emergetic terms the natural resources, renewable or not, prevalently qualitative, ‘free’ indicators are used, that used to obtain goods and services. In the urban and investigate single arguments without capturing the territorial planning spheres, typical problems, such as complexity of the phenomena, which therefore makes it the search for the optimal demographic size of a city difficult for the layman to understand. and the rational spatial allocation of its functions, arenow approached by looking for the most efficient If ecology can be said literally to study ‘life in the home’ emergetic configuration as far as the transformation and economy to ‘manage the place where one lives’ it hierarchy is concerned. Huang (Dept. of Urban and follows that there is an affinity between the two Regional Planning, University of Taipei, Taiwan) has disciplines (Odum E., 1988); furthermore, given that the developed this theme in great detail, applying it to the dominion of the phenomena examined by the former capital city, Taipei, which over the last twenty years has is larger than that of the latter, environmental impact grown at an extremely fast rate. Emergetic analysis should be evaluated first in energetic terms, then in evaluates the environmental sustainability of a territory monetary terms, as thermodynamics can be considered over an established time period, usually one year. It is ‘a physics of economic value’ (Georgescu Roegen, 1982). put into practice by calculating the emergetic quantities Therefore, rules and investigation methods can be consumed and interpreting the results with the aid of acquired from the ecological sciences. In the same way suitable indicators. It is divided into five basic phases, as studies on ecosystems (autonomous functional units, created by applying the rules of graphic representation each formed by a community and its physical (Fig. 1) and calculation (emergetic algebra), taken from environment), territorial analyses are developed the language of consolidated scientific disciplines like (anthropogenic ecosystems) to verify the sustainability ecology and systems organisation theory (Lokta, 1922; of the transformations that take place there (Amata, von Bertalanffy, 1968; Odum H. and E., 1983). The initial phase consists in identifying a ‘territory as a unit of Past attempts at physically measuring the inputs and production’ (Amata, 1982), the borders of which do not outputs of economic transformations came up against necessarily coincide with the administrative ones, but numerous obstacles among which the impossibility of which are defined on the basis of physical-chemical, totalling heterogeneous sizes. It was then proposed to biological and economic-social processes, or by quantify them in exclusively energetic terms. But ‘a joule geological or pedological uniqueness, or by the aim of of solar energy, a joule of carbon and a joule of electrical the project. The next step is to set up a statistical energy even if they represent the same quantity of information system which regards the physical and energy, have different qualities’, or rather, it takes more socio-economical aspects in the established time joules of fuel (equipment) and even more joules of solar interval, by means of which it is possible to quantify the 3 ALLEGRA_6:rivista21x27.qxd 29/07/11 09:38 Pagina 84 resources used with the respective measurement units. resulting in the present dislocated residential situation. Initially these resources are classified as renewable or The first results regarding emergy analysis can be seen not, according to whether the time it takes to make in Table 2. Despite the plentiful supply of renewable them is less than consumption time or not, in the latter resources in the territory, especially in the metropolitan case leading to an erosion of natural capital. They are and foothills areas, which are due to the high solar then further divided into local products or products radiation, the rainfall that accumulates in underground imported from/exported outside. A graphic model of reservoirs thanks to the porosity of the volcanic soil, the the relationships between the system components and tidal and wave energy along the coast and the terrestrial the input/output flows of material and energy (third flow of heat which is particularly high on Etna, the phase), elaborated using appropriate symbols, favours emergy used in the province of Catania, as far as an overall vision of life in the territory (Fig. 2). The next renewable sources are concerned, is only 2% of the step consists in translating the factors used into total. Instead, 59% of the total emergy used derives from emergetic terms, multiplying them by the respective local non-renewable sources, among which the transformity available in literature or resulting from ad remarkable contribution made by lava and basalt, hoc analyses. Finally, from the results, it is possible to greatly used in the building industry, determined both extract a series of environmental performance indicators by the great quantity extracted and by the consistent relating to the emergy density (sej/km2) of the territory, value of the transformity (7.56x109 sej/g), a sign of their to specific consumption per inhabitant (sej/ab), to the long geological formation time. The 39% of the total ratio between non-renewable and renewable emergy emergy used comes from outside (17,737x1018 sej) and used (environmental loading ratio) and between is subdivided between con-sumption of energy reserves imported and local emergy (emergy investment ratio). (electricity and vehicle fuels) and consumer goods. The Moreover, the ratio between the total emergy used and gap between exports and imports (about 30%), typical the GDP (Gross Domestic Product) measures the of a southern economic situation in which 70% of local amount of emergy that was necessary to create one euro workers are employed in commerce and only 18% in of monetary wealth. A high index can indicate manufacturing, can be seen in the statistics of both the inefficient production, with a waste of resources, but it physical quantities exchanged and the corresponding is also typical of countries supplying raw materials, emergetic values. The emergy density (around 13x1018 usually sold at a price that does not take into account sej/km2 on average) illustrates an uneven distribution among the three districts, with the highest values It was agreed to divide the province of Catania into appearing in the metropolitan area (35x1018 sej/km2), three sub-systems, each having different characteristics: where a reduced territorial area corresponds to a greater the greater part of the foothills area, the metropolitan concentration of local resources, (the sea and the lava area (with part of the foothills) and the Caltagirone area. stone quarries), and residential districts. Moreover, the The whole province covers a surface area of about 3,552 policy-making and ruling authorities of the whole km2 and is made up of 58 communes with a total of province are concentrated in the city of Catania. The 1,075,657 inhabitants (Fig. 3). A combination of particular environmental loading ratio, or degree of sustainability, geological, biological and landscape conditions has indicates that for each renewable emergetic unit, 49 given this territory a very variegated environmental non-renewable units are consumed: a situation which framework, characterised mainly by its volcano, Etna, in the medium to long-term can only become alarming and the Ionian Sea coast which ranges from gravel in the as regards its territorial load. From the emergy foothills area, the most northerly of the three sub- investment ratio (equal to 0.6) it can be deduced that for systems, to rocky and then sandy in the metropolitan each local emergetic unit, only 0.6 is imported. However, area to the south. The metropolitan area (A.M.) (Fig. 5) this does not mean that the province is productively consisting of 27 communes, with 748,153 residents on a autonomous, rather, it means that local minerals are surface area of 952 km2, has the highest residential wasted. In particular, the figure close to zero (0.3) density in the province: over 78,000 inhab/km2. The relating to the foothills area, can be interpreted by administrative and economic heart of the entire observing that works aimed at completing the food province, it features a complex conurbation settlement chain with the conservation and transformation of system, caused by the wildfire spread of the urban typical products could be profitable, because it is based perimeter that took place at the beginning of the on a valorisation of abundant local resources. From a Seventies, when both neighbouring communes and comparison made with the analyses carried out by other surrounding countryside were absorbed. This was due authors in four different Italian regions, Bologna, to the city’s population moving initially towards the Cagliari, Pescara and Siena (Tab. 3), it can be seen that immediate hinterland to satisfy the immediate need for the indexes for Catania are lower than the average. In housing, then, once this area had reached saturation particular, a comparison between the resources point, towards more distant towns also in order to buy consumed and monetary wealth produced (GDP), second or third seaside or mountain holiday homes, expressed in 2006 prices, resulted in a value of 259 sej/€ 3 ALLEGRA_6:rivista21x27.qxd 29/07/11 09:38 Pagina 85 Analisi emergetica per la riqualificazione territoriale: il caso studio della Provincia di Catania for Catania, little more than the average calculated in urbanisation works and housing, obtained by multiplying the other four cases. Given that in the 2001-2006 period the 7,070,000 m3 of building land, specified by the Catania emerged as one of the poorest Italian provinces planners, by the unit cost of 1.07x1015 sej/m3, which as regards per capita income, this result is symptomatic regards the creation of a reinforced concrete building for of an inefficient emergetic structure. civic use (Pulselli et al., 2007) (Table 4). In the case of San To improve the performance of the indicators in the Cristoforo South, emergy consumption is clearly less, province of Catania some proposed measures are: a) given that soil erosion does not have to be taken into besides monitoring the quarries, the environmental consideration because the soil has already been restoration of the disused ones and reuse of the minerals; waterproofed and the road infrastructure and distribution b) an increase in energy production from alternative networks have almost all been developed, while the energy sources; c) the rehabilitation and densification of building volume is limited to new residential buildings degraded areas in the city, particularly in the metropolitan and the integration of secondary urbanisation works. It area, to combat a further extension of the town would, therefore, be desirable to extend the boundaries and the surrounding communes, to reduce redevelopment works planned for San Cristoforo South the loss of agricultural land and countryside and the use to the so-called ‘historical’ degraded, marginal areas of of building materials. As regards the latter, this essay has the city, demolishing and removing the numerous developed an ex ante comparison of the costs of crumbling dwellings of little historical-architectural value urbanisation, expressed in emergetic terms, for two and using these areas for residential buildings that suit important types of settlement in the city of Catania: the the context, so as to satisfy, at least in part, the need for plans for cheap housing in Librino drawn up in the housing and limit the waste of natural resources. Seventies but still not complete (Fig. 7), and the recently- However, a recent revision of the town plans for the launched redevelopment of part of the historical communes on Etna included further urban expansion, in extra-moenia quarter of San Cristoforo South (Fig. 8). The the name of a supposedly unstoppable demographic following have been calculated as regards Librino: a) the growth, which was estimated without the preliminary loss of emergy caused by soil erosion on what was once creation of any planning tools for the metropolitan area, arable and grazing land; b) the costs of primary and ignoring any opportunity to restore consolidated urbanisation works, limiting the investigation to a calculation of the materials used (the factor mostaffecting emergetic analysis); c) the costs of secondary Key words: entropy, evaluation, emergy, region * Laureata con lode in Ingegneria Edile nel 2000 presso la Facoltà di Ingegneria dell’Università di Catania, ha conseguito il diplomadi master in “Procedure di valutazione di impatto ambientale” presso la Scuola Superiore dell’Università di Catania nel 2001. Nomi-nata cultore della materia in “Economia e organizzazione aziendale” ed “Economia e cultura d’impresa” nel 2001, ha svolto attivitàdi tutoraggio e assistenza alla didattica per codesti insegnamenti dal 2001 al 2003 e nel 2010 presso la Facoltà di Ingegneria (Univer-sità di Catania). È stata assegnista di ricerca dal 2004 al 2008 nel settore scientifico disciplinare ICAR/22 (Estimo) e professore a con-tratto di “Economia applicata all’ingegneria ed estimo civile” negli A.A. 2006-07, 2007-08, 2008-09 presso il Dipartimento di Inge-gneria Civile e Ambientale della Facoltà di Ingegneria (Università di Catania). Bibliografia
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