Resource efficiency in the German copper cycle: Analysis of stock and flow dynamics resulting from different efficiency measures

In the context of the increasing depletion of finite natural resources and associated environmental and social problems, it is vital for societies to understand the drivers of resource demand and develop strategies to reduce its negative impacts. One such strategy is the move towards a circular economy, in which linear industrial systems are turned into circular systems where former waste streams from one part of the system can act as inputs in other parts. This includes the substitution of primary with secondary materials, thus reducing some of the negative impacts of primary production. The extent to which this is possible depends on the amount of retired material stocks that are made available for re-use. This article develops a methodology for analyzing material flows in relation to the wider economic system for the special case of copper. For this, a macroeconomic simulation model and a substance flow model are coupled to determine sectoral copper demand on the one hand, and the availability of secondary copper on the other hand. A number of scenarios aimed at reducing primary copper demand or increasing the supply of secondary copper are modeled. The results vary considerably between scenarios, depending on which material efficiency measure is analyzed. Due to delays in the retirement of copper stocks, trade-offs can be observed between reductions of original material demand and the availability of secondary material.