Life cycle assessement of vehicles with alternative powertrains

Abstract

The reduction of Carbon Dioxide (CO2) is a central topic of environmental policies in Europe and worldwide, with a large focus on sustainable mobility. Initiatives are taken to enable sustainable mobility by optimising existing vehicle powertrain technologies such as conventional combustion engine vehicles and developing alternative powertrains such as electric vehicles, (plug-in) hybrid electric and fuel cell electric vehicles. Given the conceptual difference of energy deployment where vehicles convert primary energy into operating (propulsion) energy on-board or use loaded already converted energy for propulsion, environmental assessment of vehicles based only on direct emissions is not adequate. New methods are needed to determine the environmental burden whereas life cycle assessment provides the most comprehensive information. The work provides a data inventory for production and operation of vehicles with conventional and alternative powertrains for four geographical regions: United States, European Union, Germany and Austria. Through vehicle simulation and data inventories the CO2 emissions of vehicles have been assessed for their full life cycle. The results show that according to the simulated current test procedures, electric vehicles provide the most potential for enabling CO2 sustainable mobility, currently resulting in an average of 30% less CO2 compared to the most inefficient vehicle. However, the electric vehicle is highly dependent on local conditions of used electricity generation and CO2-efficiency of traction battery production. It is found that the regulated assessment procedures for electric and fuel cell vehicles in Europe do not accurately reflect on the actually caused CO2-emission associated with their propulsion, but only on the local emissions. Significant differences are exhibited in production and operation of vehicles between the regions, whereas the case of Austria demonstrated the importance of CO2-efficient electricity mix through multiple sensitivity analyses. Electric vehicles provide a great potential, however, further improvements are urgently required to enhance its actual environmental profile. Primarily, the global CO2 efficient electricity generation from renewable sources must be increased and the supply chain impact of battery production improved. Also, environmental assessment regulations of vehicles require urgent improvement as to take into account the environmental cost of primary energy conversion used for propulsion.