Cycles of critical metals : dissipative losses and potential optimizations

Many materials have a growing importance for our society as well as a growing supply risk, which together is referred to as the criticality of materials. Many metals, particularly those that are fre-quently considered to be critical, are used in dissipative ways along the product life cycle. Concur-rently, there is a lack of consensus in nomenclature on dissipation as well as of methodological ap-proaches to assess dissipation. This has been addressed in this thesis by providing a concise defini-tion and classification of dissipative losses, by implementing this definition into the material flow analysis methodology, and by exemplarily applying the methodology to selected metals, which are most frequently considered to be critical. The analysis focuses on selected applications: indium and gallium in CIGS photovoltaic cells, germanium in polymerization catalysts, and yttrium in thermal barrier coatings in aircraft engines. The outcomes of the prospective case studies, which focus on products used in Germany, include information on the hot spots regarding the occurrence of differ-ent types of dissipative losses and potential optimizations. Such knowledge is of value for achieving a more sustainable materials management which reduces environmental impacts of material use. Based on the methodological description and case study outcomes provided in this thesis, future studies with similar scope may be facilitated significantly.