The joint use of LCA and emergy evaluation for the analysis of two Italian wine farms

Abstract

The aim of this paper is to evaluate two agroindustrial productive processes in their entirety (one organic and one semi-industrial), focusing on the comparison of impacts derived from the inputs and outputs of the system (life cycle assessment, LCA), integrated with a physical evaluation of the resources and natural services, on a common basis (emergy).

Methods based on the joint use of LCA and emergy evaluation are useful, as they measure the contribution of environmental services and products to the productive process thus focusing primarily on the environmental impact of emissions and non-renewable energy inputs.

The complementarity of the methods used in this paper contributes important elements and information useful for the comprehension of the organization of agriculture within Siena's territory.

The results show important elements and useful information: (1) for the comprehension of the two agroecosystems’ organization; (2) for the use of the energy flows that determine their development. Moreover, the combined use of emergy and LCA gives a comparative thermodynamic performance evaluation between organic and semi-industrial farming.

Introduction

In an age in which agriculture has assisted in the decline of energy sources, and in the pollution of soils and water tables, it has become urgent to manage natural resources in an effective and efficient way in order to sustain agricultural activity (Kang and Park, 2002). In general, agricultural economies represent a meeting point between human essential needs and nature's primary production. Since environmental issues affect so many disciplines, cross-disciplinary interaction is essential for the development of “eco-centric” methods (Bakshi and Fiksel, 2003).

Methods based on the laws of thermodynamics are useful, because they measure the contribution of environmental services and products to the productive process. Therefore their use, and the fact that they allow for a representation of all the energetic flows that feed a system, makes possible an evaluation of the sustainability of agricultural productive processes.

Life cycle assessment (LCA) in agriculture focuses primarily on the environmental impact of emissions and non-renewable energy inputs. In other words, it considers the impact of all agricultural processes in a product's life cycle, from the extraction of the natural resource to the use and disposal of the product. LCA ignores ecosystem services and products, and the final results of this analysis depend on subjective evaluation (Ulgiati et al., 2005). For this reason, it has become necessary to promote integration among methods that may be potentially complementary. Therefore, the usefulness of the emergy methodology for the ecological and economic analysis of agricultural systems and natural resources will be emphasized (Odum, 1996). In the past, emergy was already applied to several agricultural systems, both for comparative evaluations and simple agricultural systems (see for example Cavalett et al., 2005; Lefroy and Rydberg, 2003; Liu and Chen, 2005), and in particular to grape or wine productions together with exergy (Bastianoni et al., 2003).

Emergy evaluation is a method that is able to evaluate environmental and economic products and services on a common basis, that of the equivalent solar energy, called “solar emergy”, or “solar memory energy” (Scienceman, 1987). All systems and their inputs and outputs are organized hierarchically, considering their importance within a web of relationships, introducing the concept of “energy quality”. Emergy evaluation is a powerful tool, for it is one of the very few methods that accounts for the contribution of ecological products and services. The main potential of this method is normalizing forcing factors, state variables, and other system attributes to one metric unit, namely solar emergy (Tilley and Swank, 2003).

The importance of this paper derives from the combined use of emergy and the LCA for the comparative thermodynamic evaluation of two wine producing farms—one using organic and one conventional farming methods—both situated in the Province of Siena, Italy. The aim of this paper is to evaluate the agroindustrial productive processes as a whole, focusing on the comparison of impacts derived from the inputs and outputs of the system (LCA), integrated with a physical evaluation of the resources and natural services, on a common basis (emergy). The complementarity of the methods used in this paper contributes important elements and information useful for the comprehension of the organization of the two agroecosystems and the use of the energy flows that determine their development, in relation to the importance that agriculture holds for the territory of Siena.