The importance of system boundaries for environmental assessment of vehicles

Sammanfattning: Vehicles are generally viewed as having their major environmental impact in the use phase because of combustion emissions. New technology can significantly decrease use emissions. These advantages suggest a rise in alternative vehicle drivetrains, e.g. electrical motors as well as a decrease of fossil fuel engines. It is of importance to consider what impact this technical shift might have in a lifecycle perspective. New technology requires specialised materials which in turn have substantial impacts during raw material extraction, manufacturing, and end of life. This means that the utilised materials may affect the total life cycle impact of a product. The impact can shift to other life phases and additionally give rise to impacts other than the frequently used energy consumption and climate change. The aim of this thesis is to understand how system boundaries effect environmental impact assessment. Potential life cycle assessment issues are investigated through studies of vehicle environmental impacts in different lifecycle phases and varying system boundaries. These issues are approached through several tools: LCA, Environmentally Responsible Product Assessment (ERPA), and Material Hygiene (MH). Three publications are appended to this thesis. Publication A compares two different disposal scenarios for end of life vehicles in Sweden. Publication B compares complete life cycle impacts of two dissimilar drivetrains in similar vehicles. Publication C investigates potential benefits of a concept sea vessel by comparing it with cargo transport by trucks. To fairly compare vehicles, with different drivetrain technology, it is not advisable to apply assessment that is limited to studying the use phase. Neither is it reliable to limit impact inventory to only energy use and CO2 emissions. The consequences of a narrow system-boarder are difficult to keep track of. To avoid sub-optimising and minimise risk of unawareness of trade-offs life cycle perspective is essential.