Matter matters: Material flow analysis of renewable electricity generation technologies

Licentiate thesis, 2024

The mitigation of human-induced climate change requires the expansion of renewable electricity sources, such as wind and solar power. The material extraction and waste flows associated with these technologies will amplify environmental and social impacts on a planetary scale, endangering a sustainable energy transition. The circular economy has the potential to decrease both the magnitude of the decarbonization challenge and the associated demands for material resources. The role of the circular economy in Closing material loops through recycling in variable renewable electricity systems has gained attention. However, its potentials for Slowing down the flow of materials through prolonging the service lifespans of renewable technologies, Narrowing the material use per installed capacity, through material intensity reductions and substitution with novel technologies, and their combined impact on embodied emissions along the materials’ supply chains, primary material demand and secondary supply availability remain underexplored.

 

Here, I use a prospective material flow analysis to assess these potentials with respect to the large-scale deployment of wind and solar photovoltaic power in the Swedish energy transition to 2050. This includes assessment of the potential for reducing embodied emissions related to the bulk materials, steel and concrete, essential for wind turbines and their foundations through circular economy strategies, longer service lifespan, and material intensity reduction. Furthermore, I investigate the potentials and trade-offs associated with reducing the primary demand and increasing the secondary supply availability for 11 minor metals through Slowing, Narrowing and Closing circular economy strategies.

 

The results show that longer service lifespan and material intensity reduction substantially reduce the embodied emissions of steel and concrete. Nonetheless, reductions in the production processes of these materials remain crucial for wind power to comply with Sweden’s decarbonization target. Narrowing strategies exert the greatest impact on primary metal demand reduction over the scenario period. While achieving the climate mitigation target, combined implementation of Slowing, Narrowing and Closing strategies reduces by more than half the required cumulative primary demands for all metals, as compared to the absence of circular economy strategies. On an annual basis, towards the end of the scenario period, the Slowing, Narrowing and Closing strategies combined substantially reduce the primary demand for all metals, while eliminating the annual primary demand for two of them. However, primary demand remains necessary for the majority of the metals throughout the scenario period, highlighting the importance of developing effective and sustainable circular economy strategies, and also emphasizing the need for demand-side measures and responsible mining practices during an energy transition with a high reliance on variable renewable electricity. Although the findings indicate that by 2050, the secondary supply could meet more than half of the gross metal demand for the majority of the metals studied, the results also highlight the limited potential of recycling during the short-to-medium term phases of the energy transition with high shares of wind and solar photovoltaic technologies.

 

Full realization of the benefits of these circular economy strategies requires the exploration of opportunities at every stage of the supply chains of wind and solar photovoltaic technologies.