Synergy of green energy technologies through critical materials circularity

Synergies between technology flows is essential to balance the consumption of their related critical materials and promote a sustainable green economy transition. Using dynamics modelling, a comprehensive analysis of silicon flows applied in green energy technologies such as photovoltaic (PV) solar panels and lithium-ion batteries (LiBs) is provided. The results show that appropriate allocation of the circular flows of different silicon grades can become an effective global solution for saving material, energy and water as well as mitigating greenhouse gas (GHG) emissions. About 15 % of required global silicon could be provided by secondary production from end-of-life green energy technologies by 2030. Recovering metallurgical, solar and electronic grades of silicon from global end-of-life PVs compared to its primary production will lead to savings of 3.5 billion GJ of energy, 3.1 million m³ of water and over 65 Mt CO₂ eq of GHG emissions globally by 2030. Also, synergies between material flows from PVs waste to advance LiBs production aims to save around 38 M GJ of energy and 0.01 million m³ of water and mitigate 4 Mt CO₂ eq of GHG emissions through secondary production practices by 2030. The findings outline a systematic solution for environmental sustainability of recycling by suggesting optimized integrated material flows of recovery of 50 % metallurgical, 25 % solar and 25 % electric grades of silicon from global end-of-life PVs.