Life Cycle assessment of locally zero emission buses in Germany
Main Presenter: Alexander Stoffregen
Co-Authors: Michael Faltenbacher
As part of the accompanying research ‘Innovative propulsion systems for city buses’ commissioned by the Federal Ministry of Transport and Digital Infrastructure and coordinated by Sphera Solutions, the holistic assessment of the practical suitability and readiness for use of the implemented e-bus systems is carried out. An essential aspect of this assessment is the analysis of the environmental impact of the different analysed bus systems. These are battery electric and hydrogen powered fuel cell bus systems, which qualify amongst other as zero emission buses under the current Clean vehicle directive of the EC. in comparison to Diesel Euro VI buses as the incumbent propulsion system. Since the environmental impacts are shifted from the actual bus operation to the provision of energy sources, especially in the case of electrically powered buses, it is necessary to consider the entire life cycle of the individual bus systems including the energy carrier supply. Also technology specific aspects such as range (translated into a potential additional vehicle demand) need to be considered and have a relevant impact on the results. In order to understand the impact of such technology specific aspects as well as the impact of choices regarding the origin of the used electricity and hydrogen, sensitivity analysis was carried out. The results which also include the consideration of the anticipated development of the German grid Mix over the course of the 12 year life cycle of the battery electric bus, will be presented as part of the presentation.
In summary, the environmental assessment shows the potential of innovative electric drives to avoid greenhouse gases and pollutant emissions, such as NOx, in bus-based public transport. The use of renewable energy sources is an essential pre-requisite for this emission reduction potential to materialise. The use of wind and PV electricity in particular means that higher GHG and NOx emissions in the production of e-buses in comparison to diesel buses can usually be offset within the first year of operation. With greenhouse gases, savings of 75–85 per cent are possible over the entire life cycle, with NOx 50–75 per cent. For battery buses, even the use of the current German electricity mix, and for FC buses the use of hydrogen from the steam reforming of natural gas already leads to GHG reductions while at the same time completely eliminating combustion emissions along bus routes in urban areas.