Using life cycle assessment to support the development of electrified road vehicles. Component data models, methodology recommendations and technology advice for minimizing environmental impact

Doktorsavhandling, 2017

The anthropogenic pressure on the Earth system already overshoots safe limits for climate change, so there is an urgent need to drastically reduce greenhouse gas emissions caused by transportation. Electric propulsion technology is a promising solution that can decouple fossil fuel use from road vehicle traffic. Additional benefits include removed tailpipe exhaust gas emissions, which currently damage human health and the environment, both locally and regionally. However, electrification of vehicles could lead to problem shifts, e.g. from the use of fossil fuels to the generation of fossil electricity. Even when combined with renewable energy, there are trade-offs between benefits in operation and added environmental load during manufacturing, shifting from airborne emissions to resource related impacts. This is because electric powertrain components require new materials and more advanced processing compared to conventional vehicle parts. The environmental impacts of vehicle electrification can be analyzed using life cycle assessment (LCA). This is a holistic systems tool, where all life cycle stages, from raw material acquisition to disposal, are investigated for potential contribution to environmental problems. For LCA of vehicles, a well-to-wheels study examines the life cycle of the energy carrier, i.e. a fuel or electricity, whereas complete LCA includes the production, use and disposal of the vehicle as such. A thorough review of the research field exposed short-comings in both methodology and inventory data. This thesis aims to discuss in what ways LCA support the development of electrified road vehicles, and present contributions on how the methodology can advance to provide better support, with the goal to minimize environmental impact of vehicles in the long term. Two component data models were developed. These estimate the mass and composition of one electrical traction motor and one inverter unit (the motor controller), calculate full gate-to-gate manufacturing inventories, and point to an existing database to establish cradle-to-gate models. Both are scalable from basic engineering parameters, build on typical design solutions and are easy-to-use. During this work, 45 new unit process datasets for manufacturing were compiled and the thesis discusses and presents useful strategies for data collection. A critical review of 79 publications was conducted. It was found that most LCA studies of electric vehicles fail to report their purpose and time scope as required by the ISO standard for LCA, making results appear divergent and creating a demand for more restrictive LCA guidelines to enhance comparability. But LCA has utility beyond comparing electric and conventional vehicles, e.g. to guide stepwise improvements in design and manufacturing. Such studies address a technical audience rather than consumers or policy makers. An LCA study in the project evaluated three electric motors with different designs and magnets. Results show that the making of aluminum, electrical steel and copper dominates the environmental load of the production. In particular, copper use is a driver of toxic impacts. The thesis stresses the importance of framing LCA studies to advise specific actors to take action and avoid future environmental impact. The thesis advises policy makers, automotive and power industries to plan and act for a conjoint development of electrified vehicles with fossil free electricity production, to attain the full climate change mitigation potential of electrification. Policy makers and automotive industries need to be aware that energy efficiency is key to low impact, while the equipment production, especially of primary metals and related toxic emissions, becomes increasingly important.