Comparative environmental life cycle assessment of several powertrain types for cars and buses in France for two driving cycles: “worldwide harmonized light vehicle test procedure” cycle and urban cycle

Abstract

PurposeEnvironmental assessments in the transportation sector are often lacking in transparency and completeness. In this article, the environmental trade-offs in road passenger transportation between conventional vehicles and electrified vehicles are compared, using life cycle assessment (LCA) methodology. Hence, the relevance of a massive electrification approach can be questioned. Assessing a set of current midsize passenger cars and buses allows for investigation of potential environmental issues. This is the first detailed LCA concerning several hybridization levels for cars and buses, and it is based on real consumption data for two traffic conditions.MethodsWe focused on the ISO standards (ISO 2006a, b) and analyzed the energy carriers’ life cycle and the vehicle’s life cycle. The functional unit is clearly defined as the transportation of one passenger over 1 km in specific driving conditions from a point A to a point B, without prejudice toward the path taken. Vehicle specifications were derived based on the available manufacturers’ data, literature, and French Institute of Petroleum (IFPEN) experts. For the use stage, two driving cycles were assessed: the “worldwide harmonized light vehicles test procedure” (WLTP) cycle and an urban cycle. France was selected as the study area, and a sensitivity analysis was performed based on a European electricity charging mix for electrified vehicles.Results and discussionBattery electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) exhibit the highest climate change (CC) mitigation potential, provided that the electricity mix has low carbon and that the PHEV is used with a fully-charged battery. With these conditions, PHEVs can perform even better than EVs. In that regard, PHEVs using only a thermic engine perform the worst in regard to CC indicator. It is also worth mentioning that electric buses are the best solution in urban traffic conditions for decreasing greenhouse gas emissions. Among powertrains, the electrified powertrains are even more important when performing in urban cycles. For other environmental indicators, such as particulate matter emissions, EVs perform worse than conventional thermic vehicles.ConclusionsThe results underline the importance of considering vehicles’ life cycles for LCA in the transportation sector and the need for multicriteria environmental analysis. Therefore, electrification of the transportation sector should not be driven by a single CC indicator, as this may generate potential environmental drawbacks. It is also crucial to adapt public policies to the local context because the results are highly sensitive to the electricity charging mix.