Material stocks and flows in the circular economy: a prospective material flow analysis for vehicles in the Netherlands for 2000-2050

Abstract

To allow society to operate within planetary boundaries, it is essential to reduce primary material consumption. The Dutch government has set goals to limit the primary extraction by half in 2030 and to be a fully circular economy by 2050. To be able to achieve this without reducing our standards of living, the only way is to extract the materials we need from the urban mine. Knowledge of the urban mine for the vehicles in our society is incomplete, and this research aims to contribute by studying the material stocks and flows for the most important road, rail, air, and water vehicles by weight in the Netherlands. An inventory is made for the materials in these vehicles between 2000 and 2017, and several sustainable transportation developments are identified which influence the material composition: (i) vehicle electrification, (ii) more effective utilisation of the vehicle fleet, (iii) lifespan elongation for vehicles, (iv) capacity enlargement of vehicles, and (v) modal shift towards low emission modes of transportation. These developments are categorised according to typologies from socio-technical transitions analysis which allow for the quantitative results to be placed in a socio-technical context and to be better interpreted. These ’transition pathways’ are then compared to a reference pathway. Bottom-up, stock-driven, prospective, dynamic material flow analysis was conducted based on exogenous driving factors describing the required transportation service for passenger-, freight-, sea- and air transportation in passenger-kilometres and ton-kilometres. These driving factors were based on the WLO-low projections for the future of Dutch transportation. Outflow was modelled using Weibull distributions based on statistical data for the demographics of vehicles. The historical stock of materials in vehicles in the Netherlands was found to have grown from 28 megatons in 2000 to 36.3 megatons in 2017. Ships contribute two thirds to total mass, cars a quarter, and the rest is in order of reducing mass: road utility vehicles, bicycles, transit vehicles, and aircraft. Ferrous metals contribute most to the total mass (82%) followed by Polymers (5.6%), Copper (3.4%), and Aluminium (3.4%). A small but important contribution is made by Critical Raw Materials, which only contribute 0.8% but the total mass of 74 thousand tons is significant. Of all studied developments, lifespan elongation reduces the primary material demand most by around 40% and the available material from the urban mine, but vehicle stock size is not influenced. Improving the effective utilisation of vehicles does reduce the stock size significantly (by 20%) and primary material demand is reduced by 35%, whilst the amount of material available from the urban mine is reduced by only 10%. Electrification of the vehicle fleet and vehicle capacity enlargement increases the vehicle stock mass by 11% because of the introduction of heavier vehicles. The primary material demand increases strongly by 43% and the materials available from the urban mine are increased by 35%. Important steps required to continue to develop the understanding of the urban mine for the circular economy, are to interpret which proportion of the material outflows are available for reuse, and for which parts of the inflows secondary materials can replace primary materials. Other important objectives are to expand the knowledge for material content of objects in society, and the knowledge on the lifespan of materials and objects in society, because these limit the interpretation of the results the most.