Sustainable Propulsion in a Post-Fossil Energy World: Life-Cycle Assessment of Renewable Fuel and Electrified Propulsion Concepts

Abstract

In response to the challenge of climate change, the European Union has developed a strategy to achieve climate neutrality by 2050. Extensive research has been conducted on the CO2 life cycle analysis of propulsion systems. However, achieving net-zero CO2 emissions requires adjusting key performance indicators for the development of these. Therefore, we investigated the ecological sustainability impacts of various propulsion concepts integrated in a C-segment sports utility vehicle assuming a 100% renewable energy scenario. The propulsion concepts studied include a hydrogen-fueled 48V mild hybrid, a hydrogen-fueled 48V hybrid, a methanol-fueled 400V hybrid, a methanol-to-gasoline-fueled 400V plug-in hybrid, an 800V battery electric vehicle (BEV), and a hydrogen fuel cell electric vehicle (FCEV). To achieve a comprehensive and objective comparison of various propulsion concepts that meet the same pre-defined customer requirements for system design, we conducted an integrated and prospective Life-Cycle Assessment (LCA) using the methodology of DIN EN ISO 14040/44 and the EU Product Environmental Footprint. Unlike other studies, we used an integrated approach to aggregate the Life-Cycle Inventory data. This approach combines model-based system design with physical-empirical simulation models and publicly available LCA databases. Assuming the defossilized energy scenario, it leads to more sustainable propulsion systems, regardless of the propulsion concept. The FCEV has slight advantages, while the BEV has disadvantages that can be improved by reducing requirements or adapting cell chemistry. Based on this, we recommend developing propulsion systems for the future in an open-minded manner, tailored to specific use-cases and targeted requirements, while considering the entire life cycle.