Georgia Savvidou, Energiteknik

Mitigating human-induced climate change requires large-scale deployment of renewable electricity technologies such as wind and solar power. However, the material supply chains underpinning these technologies pose environmental, climate, and social challenges and raise questions about the feasibility and equity of allocating available materials. In this context, the circular economy is increasingly explored as a means to address material demand and supply challenges and to support deployment at the scale and pace required to meet climate targets.

This thesis develops a dynamic material flow analysis model combined with explorative scenario development to assess the effects of circular economy strategies on material demand and embodied emissions. Furthermore, it introduces a framework that integrates the model with the operationalization of selected equity principles to evaluate whether material supply requirements, and their reduction through circular economy strategies, align with equitable material allocation. The model is applied to wind and solar power deployment within Swedish and European Union decarbonization scenarios to 2050. Four circular economy strategies are considered: longer service lifespans, material intensity reduction, substitution, and recycling. Steel and concrete are included to assess circular economy effects on embodied emissions, and minor metals and rare earth elements to evaluate effects on material demand, supply, and equity.

The results show that, while circular economy strategies reduce embodied emissions, transformative changes in steel and cement production remain necessary to achieve substantial reductions. For minor metals, material intensity reduction and substitution have the greatest potential to reduce total demand and associated supply requirements, with immediate effects that make them particularly relevant in the early and middle stages of the energy transition. In contrast, recycling and longer service lifetimes have more delayed effects. Results also vary across metals, with substantial differences in the compatibility of required supply with allocation based on equity principles. Overall, the effectiveness of circular economy strategies is time-, metal-, technology-, and market-share-dependent, indicating that no single strategy fits all contexts and that tailored portfolios are needed. A trade-off emerges within the transition period: strategies that most reduce gross metal demand can increase primary demand, requiring choices between minimizing total material throughput and reliance on primary supply. While the joint implementation of circular economy strategies reduces cumulative primary demand across metals by more than half and alleviates pressure on supply systems, high primary demand persists for most metals through 2050. For some metals, required supply exceeds allocation based on equity principles even under ambitious circular economy implementation.

Overall, the findings show that circular economy strategies are necessary but not sufficient to eliminate primary extraction and achieve equitable material allocation. Complementary measures are required, which may include further material demand reductions, energy demand reduction, stronger governance, and a broader reconsideration of energy transition objectives.