Thermodynamic optimisation of the use of natural resources: an agroalimentary production in a Chianti farm (Italy)

Transcription

1 Ecosystems and Sustainable Development V 23 Thermodynamic optimisation of the use of natural resources: an agroalimentary production in a Chianti farm (Italy) S. Borsa 1,2, N. Marchettini 1,2, A. Pizzigallo 1 & F. M. Pulselli 1,2 1 Dept. of Chemical and Biosystems Sciences, University of Siena, Italy 2 A.R.C.A. Onlus, Siena, Italy Abstract Agriculture is deeply based on the in loco availability of natural resources. They are mostly provided for free by the environment and often neglected by traditional accounting systems since it is difficult to measure their contribution or their physical weight with respect to the marketable input expressed in monetary units, more familiar to most people. The management of natural resources is a fundamental step toward the sustainability of a productive process. In this sense, it is necessary to answer some questions: how much does the local environment support the system? How high is the level of dependence of the system on other ecosystems? How much does the local environment contribute to make a given profit? This paper presents the environmental assessment of the use of resources for an agroalimentary production system located in the Chianti area (Province of Siena - Italy) by using Emergy evaluation, a thermodynamic based methodology introduced by Howard Odum during the 80s. The use of Emergy enables one to calculate some sustainability indicators (such as Environmental Loading Ratio, Emergy Yield Ratio, Emergy Density, Emergy Investment Ratio), able to give a systemic and holistic picture of the production process from an environmental point of view. Furthermore, this paper introduces the concept of emternality to provide a monetary measure of the contribution of Natural Capital to the system. Starting from the economic result of the productive process, the method of emternalities allows one to redistribute the income among all production factors, both marketable and environmental. Keywords: agriculture, thermodynamic indicators, sustainable development, emergy evaluation, emternalities.

2 24 Ecosystems and Sustainable Development V 1 Introduction How much does the environment support agroproductions? What is the real role of natural resources, that are not evaluated (but indirectly) by traditional economic instruments? How sustainable is a given agroproduction process with respect to other similar systems on the basis of the use of resources? Is it possible to measure the value of the environmental advantages of a biological production? Is it possible to estimate the economic value of the environmental contribution to the agricultural activity? These are some of the questions that arise among policy makers, managers, environmentalists, scientists and farmers who are interested in agriculture. Agriculture, as well as other human activity involving the environment, needs new tools to assess the level of sustainability and the capacity to survive indefinitely. Humans are threatening the basis of the life support system: loss of biodiversity, exhaustion of non renewable resources, depletion of natural capital, pollution and greenhouse effect are crucial elements never stressed by the traditional economic analyses. In the last decades, new methodologies has been developed, which are able to attribute an objective value to the environment on physical basis. They should be used together with economic parameters in order to better design the sustainable behaviour of human society. 2 Methods All evaluations presented in this paper are based on emergy methodology. Emergy was introduced by H.T. Odum during the 80s as a tool of environmental (but not only environmental) accounting [1-4]. On the basis of a thermodynamic hierarchy of energy, starting from solar energy, Odum s research has provided a measure of the environmental work necessary to generate an item or a flow. Emergy is defined as the quantity of solar energy directly or indirectly necessary to support a given system and its level of organization. The emergy of all inputs to a system is calculated in terms of solar emjoules (sej) by means of suitable conversion factors called transformities (expressed in sej/j), or specific emergy (expressed in sej/g or other units). Emergy represents a measure able to evaluate the convergence of several inputs to a system on a common basis. This allows also to classify inputs in different categories (i.e. renewable, R, versus non renewable, N; local, L, versus purchased, F, etc.). On the basis of these classes, some indicators can be computed in order to assess the sustainability of the use of resources. The Environmental Loading Ratio (ELR) is the ratio of purchased (F) and non-renewable local emergy (N) to renewable environmental emergy (R). A high value of the ELR indicates a lack of proportion between the use of nonrenewable resources with respect to renewable ones, so that environmental cycles are overloaded. The Emergy Yield Ratio (EYR) is the ratio of total emergy (R+N+F) supporting the system to the emergy of the inputs from the economic sector (F) (i.e. not provided for free by the environment). It indicates whether a process can compete in supplying a primary energy source for an economy. The

3 Ecosystems and Sustainable Development V 25 Emergy Investment Ratio (EIR) is the emergy of purchased inputs (F) divided by local emergy both renewable and non-renewable (N+R). A high level of EIR represents a sort of fragility of the system because of its dependence on inputs from other economic systems. The Emergy Flow Density (ED) is given by the emergy flow (R+N+F) supporting a system divided by its area. If this ratio is high, a large quantity of emergy is used in a certain area: this can mean a high stress to the environment and points out the land surface as a limiting factor for future development. Emternalities are defined as a measure of the environmental fraction that is embodied in economic products but which is not captured by commercial markets [5]. In the case of a production system, they could be defined as the environmental fraction which contributes to support the economic processes without leaving any footprint in the traditional economic accounting framework. In this paper the value of emternalities is calculated by using the ratio of money to emergy, that represents the value of one unit of emergy flowing through a given system, in monetary terms. This method enables to assign an economic value to those inputs without a market price, in order to redistribute the income on the basis of physical weights. 3 Results and discussion The system under study is a farm, called Pacina, in the Chianti area (Province of Siena, central Italy). It is 63 hectares large and it is mainly devoted (10 ha) to a biological cultivation of Sangiovese vine, in order to produce a good Chianti wine. A wide portion of the area (30 ha) is devoted to satellite cultivations, such as olive production and fodder plants for zootechnic activity. The rest is covered by forests (23 ha). This enables to rotate crops and safeguard the territory in the long run. Biological production and rotation of crops represent a virtuous union towards sustainability, without neglecting the economic aspects of the activity. The farm obtains 60 quintals (1 quintal = lb.) of grapes per year. The market value of production is equal to 80 Euro per quintal, a low value with respect to the costs of production. For this reason, the subsequent phases of production (i.e. production of wine) are fundamental for the economic performance of the farm. In other words, grape production does not affect the earning capacity of the farm, probably because market prices do not remunerate the environmental production factors. For emergy application to agricultural systems, see for example [6-10]. All the inputs to the system of grapes production and their emergy content are collected in Table 1. The analysis has been conducted for one hectare and one year (to avoid the seasonal oscillations of parameters). The total amount of emergy is equal to 7.84x10 15 sej/ha/year and the main inputs, expressed in quantitative terms, are the environmental ones (in particular, rain and loss of topsoil). Other inputs are relevant, such as human labour and parasiticides. Biological production implies the absence of chemical items such as fertilizers. Machines (and related fuel consumption) are also used for other cultivations within the farm and their contribution to grapes production is very low.

4 26 Ecosystems and Sustainable Development V Table 1: Emergy evaluation of grapes production in Pacina. Input Unit Unit/ha/yr Emergy per unit (sej/unit) Ref Solar Emergy (sej/ha/yr) Local Renewable Resources 1 Sunlight J 4.59 x [5] 4.59 x Rain g 8.50 x x10 5 [5] 1.23 x Wind J 2.12 x x10 3 [5] 5.24 x Geothermal heat J 3.15 x x10 4 [4] 3.78 x10 14 Local Non Renewable Resources 5 Loss of topsoil J 3.05 x x10 4 [4] 2.26 x10 15 Purchased Resources 6 Nitrogen fertilizers g x10 10 [5] - 7 Phosphate fertilizers g x10 10 [5] - 8 Potash fertilizers g x10 9 [5] - 9 Human labour J 1.50 x x10 7 [5] 1.86 x Agr. machinery g 6.02 x x10 10 [5] 6.80 x Fuels J 5.97 x x10 5 [11] 6.63 x Wood g 5.33 x x10 8 [5] 3.62 x Iron ore g 1.60 x x10 9 [5] 7.10 x Organic manure g 1.00 x x10 8 [5] 2.13 x Parasiticide g 6.90 x x10 10 [5] 1.72 x10 15 Total Emergy Flow sej/ha/yr 7.84 x10 15 A summary of emergy flows is shown in Table 2. A relevant portion of emergy is directly dependent on local environment (R+N = 52.5%), without an economic counterpart (with the exception of 10% of human labour and 29% of organic manure). Soil erosion (non renewable) represents the 28.23% of total emergy. Emergy of purchased inputs is less than 50% of total, putting on evidence a certain equilibrium between different categories of resources. Emergy indices are able to corroborate these considerations and add information about the life of the system as a whole. They are useful to understand the direction of a system s development.

5 Ecosystems and Sustainable Development V 27 Table 2: Emergy flows and indices of the grape production in Pacina. Summary of emergy flows and indices expression amount unit % Local Renewable Resources R x10 15 sej/ha/yr Local Non Renewable resources N x10 15 sej/ha/yr Purchased Resources F x10 15 sej/ha/yr Total Emergy Flow Y x10 15 sej/ha/yr R is given by the sum of items 1, 4, 10% of 9 and 29% of 14 2 N is given by item 5 3 F is given by the sum of items 6, 7, 8, 90% of 9, 10, 11, 12, 13, 71% of 14 and 15 4 Y is given by the sum of (R + N + F) ELR (N+F)/R 3.21 EYR Y/F 2.11 EIR F/(R+N) 0.90 ED Y/Area 7.84 x10 11 sej/m 2 /yr ELR is 3.21, meaning that the use of non-renewable inputs is three times larger than the use of renewable ones. EYR defines the importance of the environment in agroproductions. The farmer realizes value added thanks to natural resources, that contribute to the production together with the market goods and services. EIR is a measure of how much the system is dependent from the outside. The values of EYR and EIR are respectively 2.11 and 0.90, a good result as we will show afterwards. ED (7.84x10 11 sej/m 2 /yr) represents the convergence of inputs per unit of area, that is the measure of how intensive the agricultural activity is. Table 3 presents the results of emergy evaluation for different grapes productions in Italy, two in Tuscany (Pacina and Montalcino) and two in Piedmont (Barbera of Montaldo Scarampi and Castelnuovo Boglione). All data are referred to the emergy flows per year for one hectare of cultivated land. Pacina presents the highest environmental flows (both renewable R and non renewable N), and the lowest level of purchased inputs due to the characteristics of biological production. Although the other farms produce more grapes per hectare, Pacina presents the best measure of efficiency because the specific emergy per unit is the lowest one. ELR and ED values confirm how Pacina is following a sustainable trend in terms of environmental stress. At the same time, EYR and EIR represent the equilibrium in the use of resources: EYR emphasizes how the environment directly contribute to the production per unit of purchased input and EIR shows the low fragility of the system under study due to the low dependence of Pacina from other ecosystems or economic systems.

6 28 Ecosystems and Sustainable Development V Table 3: Comparing emergy flows and indices for different grapes productions. Flows & Indices Chianti Pacina Brunello Montalcino Barbera M.do Scarampi Barbera C. Boglione R a 1.86x x x x10 15 N a 2.26x x x x10 15 F a 3.72x x x x10 16 Y a 7.84x x x x10 16 Prod. (g/yr) 6.00x x x x10 6 Emergy/unit b 1.31x x x x10 9 ELR EYR EIR ED c 7.84x x x x10 12 Composite emt % 28.04% 19.13% 15.77% Renewable emt % 11.78% 10.46% 8.89% a R, N, F and Y are expressed in sej/ha/yr b Emergy/unit values are expressed in sej/g c ED values are expressed in sej/m 2 /yr Furthermore, the concept of emternalities can be introduced [5, 12, 13, 14]. Once we have environmentally dimensioned (in emergy) all the inputs to the system, it is possible to calculate the emternality ratios, i.e. the proportion (%) of the environmental fraction (R+N) in the entire set of inputs (Y). This index is called composite emternality ratio, while the ratio of R to Y is called Renewable emternality ratio. Table 3 show the importance of renewable resources in the production system of Pacina. The difference between the two ratios is defined as an indicator of unsustainability, but, in the case of Pacina, the flow of nonrenewable resources (loss of topsoil) is overestimated, since the erosion rate is under control thanks to the rotation of crops. The results of an emergy evaluation for a production system can be related to economic parameters, such as the value of production. In particular, the so-called emergy/money ratio, attained by dividing the total annual emergy use (the sum of environmental resources used and imports) by the economic product, can indicate the amount of resources supporting the economic performance of a territorial system. The inverse of the Emergy/money ratio, vice versa, may be

7 Ecosystems and Sustainable Development V 29 calculated to put emergy wealth in economic terms familiar to most people [2]. The last index, expressed in terms of Euro/sej, is useful in revealing assets not contemplated by economic accounting systems. As we have seen, Pacina produces 60 quintals of grapes per hectare in the unit of time (one year). The economic value of production is equal to 80 Euro per quintal, so the total value of Pacina s production is 4,800 Euro/ha/yr. The production is supported by both economic and environmental inputs, hence the economic result should split up among all production factors. The ratio of money to emergy is equal to 6.12x10 13 Euro/sej. On the basis of this conversion factor, the economic result is redistributed among all the inputs. - Local environmental renewable resources (R) : 1,138 Euro/ha/yr - Local environmental non renewable resources (N) : 1,381 Euro/ha/yr - Purchased inputs (F) : 2,279 Euro/ha/yr This could be a fairer redistribution of income among input: purchased inputs have a price (different from the above), but the amount of Euro calculated for R and N can be a useful environmental benchmark for resources management. 4 Conclusion This paper has presented an environmental assessment of an agroproduction in Tuscany, called Pacina, by means of Odum s emergy evaluation. The analysis has been divided in three sections: 1) Assessment of the grapes production in Pacina by the collection of all the inputs supporting the system (in emergy terms) and the calculation of suitable indicators; 2) Comparison of four high quality different grapes production systems in Italy; 3) Evaluation of emternalities and the contribution of the environment to the production system. The results have put on evidence that the biological production is a crucial choice towards sustainability. It allows a better environmental performance of the system, without compromising its efficiency and the quality of the final product. Furthermore, the environmental inputs represent the fundamental elements which any agroproduction is based on. Integrating emergy and emternalities enables to evaluate this contribution in physical and economic terms respectively. References [1] Odum, H.T. Self organisation, transformity and information. Science, 242, pp , [2] Odum, H.T. Environmental Accounting. Emergy and Environmental Decision Making. John Wiley and Sons. New York, [3] Odum H.T., Brown M.T., Brandt-Williams S. Introduction and Global Budget, Folio #1. Handbook of Emergy Evaluation. Center for Environmental Policy, University of Florida, Gainesville, USA, [4] Odum H.T. Emergy of Global Processes, Folio #2. Handbook of Emergy Evaluation. Center for Environmental Policy, University of Florida, Gainesville, USA, 2000.

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