Stefan Pauliuk
University of Freiburg
Stefan Pauliuk is an internationally recognized sustainability researcher with expertise in accounting, assessment, and prospective modelling of industrial systems and sustainable development strategies. His research focuses on quantifying the potential for material and energy efficiency in the steel and copper cycles, on the development of indicators for sustainable development, and on sustainable use of biomass and land. He has worked at the intersection of different model frameworks, including material flow analysis and life cycle assessment. He has contributed to the research on the system-wide effects of the circular economy by applying material flow analysis, life cycle assessment, and input-output analysis to material cycles. He devised an extension of the System of Environmental-Economic Accounting (SEEA) that includes waste flows, cascade use of waste and by-products, as well as detailed capital accounts. He also contributed to the detailed analysis of global supply chains by integrating physical and monetary multiregional input-output models. Stefan Pauliuk is assistant professor for sustainable energy and material flow management at the faculty of Environment and Natural Resources at the University of Freiburg, Germany, were he is currently building up a research group for industrial ecology. Research and teaching at the faculty focus on the protection of natural resources and the adaptation of ecosystems and human-environment systems to global change.
Closed material cycles are at the core of sustainable development, but a comprehensive techno-economic model of the different material cycles to study the future effects of the different strategies for closing material cycles does not exist. We present the conceptual framework of a material systems model (MSM) that represents the coupling of the cycles of different materials in the mining stage, in alloys, in products, and again in the waste management industries. The model allows to assess the system-wide effects of major technical determinants of the different material cycles, including: material substitution, material efficiency, the dependency of minor metal supply on host metal demand, functional recycling, and ‘down-cycling’. The economics of material cycles are reflected by the costs of material production, recovery, and recycling. The future scale of the material cycles in the model is determined endogenously by coupling the MSM to different socioeconomic scenarios, such as the Shared Socioeconomic Pathways, and by the model’s decision making routines that minimize greenhouse gas emissions, non-functional recycling, critical material consumption, or a combination of those. The purpose of the MSM is to i) quantify the linkages between human development, material use, and environmental impacts (mainly climate change and resource depletion), (ii) determine economically and environmentally optimal material substitution levels and recycling strategies, and (iii) inform about linkages between metal cycles that represent bottle necks in the future upscaling of metal services.
The model framework combines previous material cycle modelling approaches within industrial ecology and beyond into a larger dynamic framework. The previous model approaches include the dynamic material cycle models for steel, aluminium, and copper, the tracing of secondary materials through products, the study of recycling alloys and material substitution in the automotive sector, the coupling between major and minor metals, material flow cost accounting, optimisation, and the material aspects of energy system modelling.
MSM and energy system models together provide a complete biophysical description of socioeconomic metabolism, and the MSM can be linked to more aggregated scenario models such as integrated assessment models to study the contribution of material efficiency etc. to climate change mitigation and to quantify the consequences of a wide spectrum of sustainable development strategies on the material cycles. The MSM has a modular software structure and is designed as an open source community tool.
We present a first application of the MSM framework on the copper cycle. Copper is a crucial metal for both the transition from agrarian to industrial societies and for the transition to renewable energy supply. Non-functional recycling of copper, e.g., by dilution of copper in secondary steel, increases demand for primary copper production and is detrimental to steel quality. The future extent of and concern associated with non-functional recycling depends on the development of all metal and product cycles involved: the magnitude and quality of the vehicle and electronics scrap flows, the demand for secondary steel of different qualities, and the demand for copper. The MSM framework can tackle those couplings between the metal cycles at different stages.
• Socio-economic metabolism and material flow analysis , • Advances in methods (e.g., life cycle assessment, social impact assessment, resilience a , • Circular economy
