Material and Energy Flow Analysis and Associated Environmental Impacts of Swiss Mobility

The development of material flow analysis (MFA) on large-scale systems is challenging due to the complexity and breadth of data that are required and the magnitude of the mass flows involved. This is true, for example, when trying to determine the material and energy flows at the country level of a whole sector, such as mobility. Various studies have provided data on particular aspects of these flows, but they often use different methodologies and generate inconsistent results. The challenge is to structure the data system without getting lost in details. In the frame of this study the mobility sector of Switzerland, defined as the entire vehicle fleet moving inside the country, has been for the first time intensively assessed using a bottom-up approach and depicted in a simple flow diagram (Sankey). 78 categories of vehicles - from electric and not electric bikes, cars and buses to airplanes passing through trains and boats - nine types of materials and two types of energy sources have been characterized. For each of the 78 categories, different studies and statistics on quantity, material composition, growth rate, lifetime, fuel consumption, distance travelled and end-of-life paths have been examined. Different data sources served as a starting point for developing the material and energy flow analysis. The 78 categories have been aggregated into 12 groups. For each of the groups the actual stock as well as the ingoing and outgoing flows have been calculated. Additionally, the amount of fuel and electricity needed to move the vehicles and the amount of greenhouse gases emitted have been calculated and represented in the same Sankey diagram by depicting the flows in annual tonnes oil- and CO2-equivalents, respectively.