Views
5 years ago

BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

44 3 Life cycle

44 3 Life cycle assessment of biofuels: methods and tools It is important to acknowledge that while the calculations of the quantitative results regarding individual environmental parameters can be carried out with scientific objectivity, with regard to the overall comparisons no objective final conclusions can be drawn. These depend on the particular objective of the decision maker. Thus all fuels investigated here have advantages regarding certain environmental parameters and disadvantages with respect to others. For instance, the results of the project generally show that the cultivable biofuels like rape seed and triticale tend to perform better than fossil fuels with regard to emissions of CO2 and equivalent greenhouse gases, but the nitrogen and SO2 emissions are much higher for these due to agricultural production. It is therefore up to the particular decision maker which parameter to assign a higher ecological importance. Regarding the procedure for the assessments, first the relevant LCI and parameters and LCIA categories were chosen according to the impact assessment procedure outlined in Chapter 3.4. Following the calculations of the values for these parameters, the results were processed graphically, described verbally and compared against each other. The assessments were carried out on a country specific basis as well as for the whole EU (see Table 2-1 in Chapter 2.1). 3.5.2 Interpretation concept: biofuels versus fossil fuels First, the various biofuels investigated by each participating country were compared against their fossil counterparts on the basis of complete LCAs with regard to the parameters chosen in the impact assessment. The quantitative results were obtained using the functional unit (MJ of heat, electricity, or heat value in the fuels – depending on which form of energy the particular biofuel was intended to produce). Therefore the result e. g. for the comparison between biofuel B and fossil fuel F with regard to the parameter “Use of fossil fuels” would be expressed in the following way: If biofuel B replaces an equivalent amount of fossil fuel F, then X MJ of fossil energy resources would be saved for every MJ of biofuel consumed. This was then expressed in diagrammatic form. In this way, it is possible to compare the results for a certain fuel with regard to each impact category with those of other fuels regarding the same parameter. Concluding Interpretation An interpretation in the sense of a concluding interpretation will not be carried out here. This is the responsibility of the user or decision maker, because for this purpose, definite subjective assessment criteria are required – as for example the decision regarding the importance of the environmental impact categories and LCI parameters respectively. It is commonly accepted that these cannot be defined scientifically and may differ from person to person. Thus the results presented here may serve as a tool for any decision maker to arrive at his or her own conclusions, depending on the particular objective. For instance, if saving the greatest amount of abiotic resources is aimed for, a different fuel may be optimal than if the objective is to reduce greenhouse gas emissions, and yet another fuel might be chosen if human toxicity is the main issue. Such decisions cannot be made within this study. However, by presenting the results in a clear and comprehensible way and by discussing the quantitative results, an attempt was made to provide a scientifically sound foundation for such decisions. 3.5.3 Interpretation concept: Biofuels versus Biofuels The purpose of this part is to examine which biofuels should be preferred to others (it is not subject of the study to compare the fossil fuels among themselves). For those countries that did not normalise the results (see Table 3-3), this has already been included in the comparison of biofuels versus fossil fuels. For the group of countries that did normalise their results, the normalisation procedure is as for the comparison biofuels versus fossil fuels described above. The comparisons between the biofuels are based on the individual comparisons between each biofuel and its equivalent fossil fuel. For instance, if RME is compared to ETBE, what is actually compared are the respective advantages or disadvantages of RME versus diesel oil and ETBE versus gasoline.

3.5 Interpretation 45 Fossil fuel production system A Fossil fuel production system B Comparison type I Comparison type I Biofuel production system A‘ Biofuel production system B‘ Difference between fossil fuel and biofuel Comparison type II Difference between fossil fuel and biofuel Figure 3-5 Schematic representation of the types of comparisons carried out in this project Selection of biofuels to be compared With regard to the comparison of the various bioenergy carriers among themselves, it is necessary first of all to identify those biofuels which are to be compared, because it is only sensible to compare all bioenergy carriers with each other under certain conditions. If for example the question is whether or not it is ecologically advantageous to cultivate energy crops, then a comparison between RME and residues such as swine excrements or wheat straw is not adequate. It is similarly irrelevant to compare wood chips with bioethanol and RME if the question is if and how conventional fuels for transportation can best be substituted by biofuels. Thus depending on the question, different sets of biofuels should be compared against each other. For instance, if the question is which bioenergy carrier should be produced, the efficiency of production with regard to the land area is of foremost interest. If on the other hand the question were the production of which biofuel would save the greatest amount of fossil fuels, then the sum of all fossil fuels would form the basis of the assessment. Apart from the choice of which bioenergy carriers are to be compared with each other, the reference unit regarding the quantitative results is to be defined for the description and interpretation of the results. These are generally derived directly from the question itself. Four questions have been defined in this context, which are being addressed by different countries. Hence in this assessment step it is first of all necessary to identify the comparisons between biofuels for the different countries, with respect to the individual questions. Therefore, ultimately all potential bioenergy carriers to be compared must be identified and grouped together for every question and every geographical coverage. In Table 3-4 the comparisons to be made between the bioenergy carriers with regard to each country are marked, i. e. in this project 24 groups of different bioenergy carriers are compared among each other. Table 3-4 Questions to be answered by each country concerning the comparison between the biofuels Objective Austria Denmark France Germany Greece Italy Netherlands Switzerland Heat X X (X) X X X Transport (X) X X Land use X X (X) X (X) X Resources X X (X) X (X) X (X) (X) X Heat: Which bioenergy is the most ecological if the aim is to produce heat? Transport: Which bioenergy is the most ecological if the aim is to produce fuel for transportation? Land use: Which bioenergy is the most ecological if the aim is to make most efficient use of the available land? Resources: Which bioenergy is the most ecological if the aim is to save conventional energy carriers? (X) = Interpretation not carried out separately EU

Bioenergy Update 10-02 - General*Bioenergy
Maximising the environmental benefits of Europe's bioenergy potential
Desktop Management Tools — Which One Is the Best?
Choose The One That Best Fits Your Lifestyle! - Java Fundraiser