Life cycle assessment of sunflower and rapeseed as energy crops under Chilean conditions

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Abstract

An option for the agriculture and energy sectors in Chile is the cultivation of energy crops, but environmental studies are first needed in the framework of a sustainable national energy policy.

In this study, we used a cradle-to-farm gate Life Cycle Assessment (LCA) to compare environmental impacts and energy and water demand of rapeseed (Brassica napus L.) and sunflower (Helianthus annuus L.) in Chile, as potential oleaginous crops for first-generation biodiesel production. National agricultural data are used for the LCA inventory and process data of international databases are adapted to local conditions. The effect of field N2O emissions and land use change is evaluated. The results indicate that, compared to sunflower, rapeseed production has a better environmental performance in 9 out of the 11 impact categories evaluated, and lower water consumption. The energy demand of rapeseed is 4.9 GJ/t seed, 30% less than that of sunflower. Mineral fertilizers cause the highest environmental impact in both crops. The analysis of the life cycle of fertilizers indicates that extraction of raw materials and its production are key stages. Attempts to reduce the environmental impact and energy requirement of both crops should be mainly associated with the evaluation of other types of fertilization. In addition, particularly for sunflower, low impact herbicides should be evaluated, seed yield improved and cultivation practices optimized. If the crops are produced on degraded grasslands, the greenhouse gas emissions may be reduced.

Introduction

More than 70% of the total energy demand in South America today is provided by fossil fuels [1]. In Chile, in 2007, they accounted for 73% of the national energy consumption and imported fossil fuels provided 66% of consumption [2]. The Chilean government is developing an energy security policy with the aims of becoming more self-sufficient, diversifying energy matrix and promoting national renewable energies in a framework of environmental sustainability.

Biofuels, as renewable energy sources, are an alternative to the national dependence on fossil fuels, particularly biodiesel for the Chilean transport sector [3]. Local development of first-generation biofuels would also be an opportunity for Chilean agriculture. By cultivating energy crops, this sector would be able to use high-level technology, promote participation by small and medium-size farms, generate new focal points of development and employment in regions with high potential for energy crop production, and contribute to the country's energy policy [4]. However, the potential cultivation of energy crops in Chile, as in other countries, is also a challenge for agriculture, such as the environmental risks associated with nitrates, phosphates and pesticides contamination, as well as the reduction of biodiversity if crops are cultivated in monoculture farming [5].

For the national production of biodiesel in the short term, the major oleaginous crops under consideration are those already grown there, well adapted to the local edaphic and climatic conditions, such as sunflower and rapeseed [6]. The potential agricultural land devoted to both crops for first-generation biodiesel is around 300,000 ha/year [4]. By using potential land available, without changing the destination of current consumption of sunflower and rapeseed, there would be enough space for developing these crops for biodiesel without competing with those grown locally as a food source. Technical and economic reports on the future implementation of energy crops and biodiesel in Chile, which have recently been published [7], [8], indicate that rapeseed has more potential for development than sunflower. However, at the national level, there is a lack of environmental data on the production cycles of these crops, with a need for comprehensive research on environmental criteria to minimize impacts associated with the cultivation of these energy crops in Chile.

Using the life cycle assessment (LCA), a methodology already applied to agricultural systems, the environmental sustainability of energy crops can be evaluated, determining potential environmental impacts with a holistic and quantitative approach. There have been several examples of LCA studies applied to energy crops and their agricultural products, over the last few years, in countries such as the USA, Spain, Sweden, Brazil, Malaysia, the UK, Germany, Ireland and Australia [9], [10], [11], [12], [13], [14], [15], [16]. The research has mainly been on resources consumption and emissions; relation between environmental impacts and production; effects on land use and agricultural activities with a major impact and energy demand. Most international research on environmental impacts and energy of bioproducts from sunflower and rapeseed has focused on energy evaluation and greenhouse gas emissions [17], [18], [19], [20], [21], [22], [23], [24]. Little research has been carried out with these crops to evaluate various environmental impacts together [5], [25], [26], [27]. The direct application of the results of these studies to Chile is also not appropriate due to the differences in many factors, including agricultural practices, soil types, available technology, types and application rates of agrochemicals, distribution logistics of agricultural inputs and the country's energy profile.

We have used LCA for quantifying, in a comprehensive approach, the environmental impacts and the energy and water demand of sunflower and rapeseed production in Chile, in order to provide the country's agricultural sector with environmental criteria for the potential implementation of these energy crops, contributing to decisions being made from the point of view of sustainable development in national renewable energies.

Section snippets

Methodology

LCA evaluates potential impacts throughout the life cycle of a product, process or activity, from the extraction of raw materials through production and use, to final disposal. The ISO 14040 guide [28] presents LCA in four stages: goal and scope definition, inventory analysis, impact assessment, and finally, interpretation. This section is based on the ISO 14040 standard and is subdivided into: (1) objectives, (2) functional unit, (3) crops evaluated, (4) system boundaries, (5) sources of

Results and discussion

Section 3.1 presents the comparisons of environmental impacts and the energy and water demand of sunflower and rapeseed. Section 3.2 examines the contribution of agricultural inputs to the environmental impacts. Section 3.3 analyses the impacts of the life cycle stages of fertilizers, a key input for many crops. Finally, Section 3.4 evaluates the effect of field N2O emissions and land use change on the results.

Conclusions

There is a major international effort to improve the availability of data for LCA, but there is a general lack of local data in developing countries. International databases are an important source of information and it is necessary to review the data to ensure that the information is adequate for studies outside their coverage and, if possible, adapt it to local conditions. For this LCA we drew up an inventory for the production of sunflower and rapeseed in Chile, potential energy crops for

Acknowledgements

The present work was supported in part by DURSI (Generalitat de Catalunya), project number 2005 SGR 007, SosteniPrA. The authors wish to thank Juan Tay of the Chilean Institute of Agricultural Research (INIA) and Rebeca Iglesias of the Office of Studies and Agrarian Policies (ODEPA) of the Chilean Ministry of Agriculture for help with local information on rapeseed and sunflower crops. A. Iriarte is funded by The Carolina Foundation of Spain and the Chilean Ministry of Planning.

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