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42 3 Life cycle

42 3 Life cycle assessment of biofuels: methods and tools The values for the human toxicity category tend to be rather uncertain. The reason for this is that it is extremely difficult to obtain reliable input data (emission and characterisation factors) for all toxicity parameters of relevance. Furthermore, within the scientific community the methodology on the assessment of toxicity is still being discussed. 3.4.3 Parameters and coefficients used The different emitted substances can be aggregated by the use of an equivalence factor system according to the efficiency of the substances with regard to the environmental impact categories. In Table 3-2 the characterisation factors used for the calculations are shown. For the characterisation factors regarding human toxicological impact potentials see Annex 7.5. Table 3-2 Characterisation factors for non-toxicological impact potential categories (see text for references). Substance name Formula Global warming potential (g CO2-eq./g) 100-year 500-year Acidification potential (g SO2-eq./g) Nutrient enrichment potential (g NO3-eq./g) POCP 4 (g C2H4eq./g) Ammonia NH3 - - 1.88 3.64 - Ammonium NH4 + - - - 3.44 - Benzene C6H6 - - - - 0.2 Carbon monoxide CO 2 2 - - 0.03 Carbon dioxide 1 CO2 1 1 - - - Hexane C6H14 - - - - 0.4 Hydrochloric acid HCl - - 0.88 - - Methane CH4 25 8 - - 0.007 Nitrate NO3 - - - - 1 - Nitrogen oxide 2 NOx 0.70 1.35 - Nitrous oxide N2O 320 180 Non-methane vola- NMVOC - - tile organic com- 3 3 0.5 pounds 3 Phosphate PO4 3- - - - 10.45 - Sulphur dioxide SO2 - - 1 - 1 Includes only CO2 of petrochemical origin 2 NOX is calculated as NO2. 3 The NMVOC cover a range of substances, and the present characterisation factors only represent estimates of average values. 4 Photochemical ozone creation potential 3.4.4 Normalisation – a preparation for interpretation According to the ISO norm 14040, the impact assessment phase must include the assigning of data to impact categories (classification) and the modelling of the inventory data within the impact categories (characterisation). These two steps were described in the Chapters 3.4.2 and 3.4.3. Further elements, like normalisation, ranking, grouping and weighting, are optional. They are used to express the results in different ways, which can make the interpretation easier with respect to certain objectives. While normalisation simply expresses the data using a different reference unit, ranking and grouping also involve subjective value choices. There is no specific rule when it makes sense to use normalisation. It is largely a matter of individual choice and personal preference. In this project, some countries applied normalisation as explained below. No other optional element has been used. Normalisation enables the decision maker to assess the environmental impact of a certain fuel regarding a particular parameter relative to the general environmental situation. Thus the “specific contribution”

3.5 Interpretation 43 of the individual ecological parameters can be expressed in terms of the “equivalent value per capita”, as has been done in certain cases in this project: of the 8 participating partner countries, some chose to present their results as LCIA parameters without normalisation, and others chose to use normalisation, which led to two distinct forms of data presentation. The choice of each country is indicated in Table 3-3. It also shows that the results for all of Europe were decided to be presented in the normalised form. They are included in the main body of the text, while all country specific results can be found in the Annex. 2010 was chosen as the reference year. Table 3-3 Country specific choice regarding presentation of results LCIA results without normalisation Normalised LCIA results France Austria Greece Denmark The Netherlands Germany Switzerland Italy Europe (EU) Those countries using normalisation chose a reference unit that appears fairly complicated, but the underlying principle is relatively simple and allows an appropriate way of assessing the relative impact of the respective biofuel with regard to the different parameters: what is being expressed is the specific environmental impact of the respective fuel relative to the environmental impact of an average inhabitant of the country concerned. The derived unit is therefore “inhabitant equivalent per functional unit”. For example, the parameter “Use of fossil fuels” would be expressed in the following way for normalised results: If biofuel B replaces an equivalent amount of fossil fuel F, then the amount of fossil fuel saved would be equivalent to the average consumption of X inhabitants per year. This way, it is possible to compare the relative effect of using a certain fuel with regard to different parameters. In order to express the results most meaningfully, it may be desirable to chose a unit generally used with regard to the utility of the fuel – thus for example a fuel used for transportation might best be expressed in terms of inhabitant equivalents per km of distance covered by a car. Furthermore, it might be necessary to chose a different order of magnitude than the functional unit is expressed in, so that the results are given in figures that are easy to comprehend (e. g. 300 inhabitant equivalents per GJ rather than 0.3 inhabitant equivalents per MJ). Thus the results would be expressed in derived functional units. This has been done with regard to the normalised results presented in this project, in order to further facilitate their interpretation. 3.5 Interpretation 3.5.1 General procedure The assessment of the environmental impacts of biofuels within this study involves two distinct parts: firstly, to compare the biofuels against those fossil fuels which fulfil equivalent purposes, e. g. conventional diesel versus biodiesel for transport. These comparisons are based on complete life cycle analyses according to the ISO 14040 – 14043 standards. The procedure for this is explained in Chapter 3.5.2. Secondly, the biofuels were compared against each other, based on the results of their comparisons against the respective fossil fuels. This is a complex task because the environmental performance of any biofuel depends partly on the objective of its use. Thus for example one biofuel might be most efficient when the goal is to produce heat, but another might be better suited for producing electricity. Therefore, the comparison between the various biofuels was carried out in the light of four different questions (see Chapter 4.3).

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