The implications of circular economy strategies on the future energy transition technologies and their impacts: Solar PV as a case study

Solar photovoltaics (PV) is expected to play a major role in global energy transition under the International Energy Agency Sustainable Development scenario (IEA-SD) to achieve the temperature goals of the Paris Agreement. However, its large-scale deployment will inevitably increase material demand and associated CO2 emissions. From a material-energy-carbon nexus perspective, this study assesses the effectiveness of various circular economy strategies and combinations in reducing material demand and mitigating carbon. This study is the first to explicitly explore the contradictions among reduce, reuse, recycle strategy combinations when addressing multiple sustainability objectives for different metal categories. A comprehensive analysis is conducted via dynamic material flow analysis and scenario analysis, covering four major metals (Al, Cu, Ni, Pb) and seven minor metals (Ag, Cd, Ga, Ge, In, Se, Te) used in four solar PV sub-technologies (c-Si, a-Si, CdTe, CIGS) at a global level for the period 2015 to 2050. Findings show that reduce & recycle combined can reduce cumulative Te demand to 100 % of available resources, and cut CO2 emissions for Ag by 94 %. However, when reuse is also applied, no further reductions in material demand are achieved, and cuts in CO2 emissions decrease to 92.5 %. Whereas for major metals, reuse & recycle combined achieve the highest cuts in CO2 emissions at 23.1 %, with recycle only accounting for 4.4 % of this cut. These results challenge the conventional wisdom of applying a universal set of circular economy strategies, implying that circular economy strategies should be selectively implemented based on specific sustainability objectives and target materials.