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BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

28 3 Life cycle

28 3 Life cycle assessment of biofuels: methods and tools comprehensively documented. Furthermore all intermediate calculations and all result tables were included in the documentation. Further information on this can be found in Annex 7.5. Goal and scope definition In this first phase all the assumptions made are defined and the framework of the LCA, including methodological aspects, is set up. The main points covered in this step are: • the goal of the LCA; reasons for carrying out the study • the target group • the function(s) of the investigated systems • the functional unit • the system boundaries, i.e. the level of detail considered, the time frame etc. • allocation procedures • the choice of the types of impact and the methodology to be used for impact assessment and subsequent interpretation • requirements on data quality • consistency of the comparison (if applicable) • type of critical review (if applicable) Inventory analysis In the inventory analysis all inputs and outputs are first quantified (according to mass, volume etc.) and then expressed in terms of the functional unit. For practical reasons, efforts are focused on the investigated product system – the main life cycle – for which data must be collected. For common input data, standardised information can be used. In some extreme cases, inputs or outputs of small environmental importance may be neglected. In a second step, all resources and emissions linked with the material flows are quantified. Regarding the emissions, as well those directly occurring in the product system (for example nitrate leaching by rape seed cropping) as those linked with the input production (for example nitrous oxide while producing the electricity needed for the manufacture of mineral fertilisers) are quantified. Impact assessment In the inventory analysis, numerous parameters may be investigated regarding emissions to the environment (e. g. CO2, CH4, N2O etc.) or types of resource utilisation (e. g. fossil fuels) as discussed in Chapter 3.4.2. In the impact assessment phase, these are first aggregated into up to fifteen impact categories according to scientific criteria (also given in the tables mentioned above). For example, carbon dioxide and methane emissions are aggregated to a single figure reflecting their impact on global warming. Each impact category corresponds to an important environmental problem (eutrophication, depletion of non renewable energy resources, ozone depletion, etc.). There is no standardised list of impact categories. The latter are to be chosen and defined on the basis of their relevance to the investigated product system and the level of scientific knowledge. In a second step, the results of each impact category can be normalised, i. e. referred to national data in order to assess their country specific relevance compared to the national total impact. This method is optional and has in this project been applied to the results for Europe and certain individual countries (see also Chapter 3.4.4 on “Normalisation”). Because of a very weak scientific soundness, the next optional step – the weighting – which consists of attributing different weights to impact categories according to their fundamental environmental relevance is not performed here. Interpretation In the interpretation phase, all results of the first three stages are verified and qualified with the help of different controlling tools. In the present study, two tools are used: • Uncertainty analysis of the MonteCarlo type in order to assess the propagation of the numerical uncertainty of all the data used (described in Chapter 3.3.2)

3.2 Scope definition of the investigated biofuels 29 • Sensitivity analysis to assess the influence of some methodological assumptions (for example an allocation procedure) on the results (described in Chapter 3.3.3). In this study, these elements are discussed within the context of the inventory analysis (Chapter 3.3). The interpretation phase concentrates in this case on the comparison of the fossil fuels versus the biofuels and the biofuels among each other (see Chapter 3.5). This includes a description of how the presentation of the results is structured and how they should be interpreted. The following chapter deals with the main methodological aspects of the study. When some elements of the method are reported in other parts of the report for more convenience, there will be an indication at the beginning of the corresponding chapter. In order to keep the text length to an appropriate size, it will be focused on the specificities of the present study. For more detailed aspects, the reader is referred to the literature quoted. 3.2 Scope definition of the investigated biofuels The main aspects of the goal and scope definition phase are described hereafter. For the goal of the study, the reasons for carrying it out as well as the intended target groups, the reader is referred to Chapter 1. 3.2.1 Functions of the production systems ISO 14040 defines the function as the performance of a production system in a life cycle assessment. Since agriculture and forestry are multi-purpose, their products can fulfil several functions. The following criteria were considered in order to determine the functions relevant in this project: • Goals and scope of the study • Motivation of the target groups when promoting biofuels • Motivation of the direct actors when implementing biofuels. From most people’s point of view, the primary purpose of the investigated biofuels is providing renewable energy. This function implies the comparison with fossil fuels and is the main motivation for the target groups coming from the field of energy and the environment. As the consumption of the energy is included in the product system because of its ecological relevance, the correct function is “provision of useful energy”. This is the primary function used in this study. In some cases, two additional functions (so-called secondary functions) may also be fulfilled by biofuels: • The function “treatment of agricultural and forestry residues” is relevant because biofuel production not only provides energy but can also improve the properties of the considered biomass significantly (e.g. by combustion). Moreover, in many cases the treatment results in a higher income for the farmer and less problems with the disposal of a residue. This function is only analysed when the biofuel production contributes to a significant improvement of the considered biomass. • The functions “preservation of land under agricultural practice for social and food security reasons” was chosen from the farmers’ and agricultural sector’s view. Energy crops fulfil this function as well. This function is the point of interest for the target group agricultural ministries and concerns only the agricultural energy crops. (Note: there was no conclusive agreement on this by all institutes involved. However, this affected neither the methodologies chosen, nor the system boundaries and other definitions, nor the results.) To sum up, the main function for all biofuels is the provision of useful energy and the reference system used for the comparison fulfils the same function with fossil fuels. In some specific cases, secondary functions must be considered. The procedure described in § 5.2.2 of the ISO Norm 14041 of associated reference systems is applied to take them correctly into account. An associate reference system complements the reference system used for the comparison in order to ensure the equivalence of the systems compared (in this case biofuels and fossil fuels). For the function “treatment of agricultural and forestry residues”, the associate reference system is the alternative way of handling the biomass. For the function “preservation of land under agricultural practice for social and food security reasons”, an agricul-

Bioenergy Update 10-02 - General*Bioenergy