Life Cycle Assessment of electric vehicles focussing on local impacts within a city region

摘要

In the media, electric vehicles (EV) are often propagated as “Zero Emission vehicles” causing a debate about the truth of this statement. This paper neutrally answers the question whether EV are environ-mentally friendlier than conventional vehicles by using the methodology of the life cycle assessment (LCA) taking all phases of the life cycle into account. Variations in the basic assumptions are included in the analysis to show the effect on the results of the following impact categories: global warming potential (GWP), acidification (AP) and eutrophication (EP). Supplementary, the ecological effect on city centres due to a high integration of EV is determined comparing only the local emission during the use phase of the vehicles and the impact on its vicinity.The results of the LCA for compact vehicles comparing a conventional vehicle with an internal com-bustion engine, an EV and a plug-in hybrid EV (PHEV) in Germany illustrate that the GWP and the AP of EV (157,18 g CO_2-Eq/km) is the lowest followed by the PHEV (178,62 g CO_2-Eq/km) while a conventional vehicle has a GWP of 256,08 g CO_2-Eq/km. Only in the impact category EP the conven-tional vehicle is superior. Around 78% of the CO_2-Eq emissions allocated to the EV arise during its use phase making the assumption for the energy mix for the charging and the consumption values very important. A variation of the energy mix by comparing three countries shows that EV charged with a mainly coal based energy mix have higher emissions in every impact category (GWP: 264,73 g CO_2-Eq/km) compared to conventional vehicles. A energy mix predominantly based on renewable energy sources reduces the impact category values significantly (e.g. the GWP is reduced to 54,92 g CO_2-Eq/km). In the future the influence of charging strategies of EV on the energy system and the implica-tions of the LCA results have to be analysed in detail. The consumption values as a basis for this as-sessment are verified by a statistical evaluation of field test data. The measured data contain infor-mation about driving routes, consumption and charging behaviour. An analysis of the consumption values of test vehicles show that these values, which are determined by using the new European driv-ing cycle, are too low. Hence, the LCA results have to be increased to gain realistic results. However, the consumption values of conventional vehicle have likewise to be investigated for a comparable result. The detailed analysis of a region in Germany (Aachen), based on a realistic driving model, quantifies local emissions such as particulate matter, CO and NOx. These emissions affect the quality of life within some regions (in particular within city centres) given a high integration rate of EV. Therefore, the traffic of the whole region is simulated with multi agent systems, determining destina-tions and driving routes of each agent automatically. This approach allows assigning of emissions to individual streets showing that a high penetration rate of EV improves the situation within city centres even though EV produce local emissions and hence cannot be called “zero emission vehicles”.