Material availability assessment using system dynamics: The case of tellurium

With the increased deployment of solar photovoltaic (PV), the cadmium telluride (CdTe) PV market is expected to grow substantially. CdTe PV production is crucial for the clean energy transition but problematic because of the material availability challenges. CdTe PV relies on tellurium, a scarce metal mainly produced as a byproduct of copper. Several studies investigated the availability of tellurium for CdTe PV. However, previous models are static and do not reflect the interconnection between tellurium supply, demand, and price. Despite the efforts, previous studies have inconsistent results and do not provide a clear understanding on the availability of tellurium for CdTe PV applications. This study uses system dynamics modeling to assess tellurium availability between 2023 and 2050. The model considers different scenarios for CdTe PV demand growth and PV material intensity reduction. The model also considers tellurium supply variables such as Te-rich ores, tellurium yield from anode slimes, and growth in copper mining. The historical data (2000–2020) analysis shows a negative correlation between the tellurium price and the annual tellurium surplus. All the considered demand scenarios exhibit a tellurium supply gap where annual material production falls below demand. Tellurium availability and price could delay the growth of CdTe PV production, and maintaining the current CdTe PV market share of ~4% will be challenging. The low-demand scenario, which is based on a constant CdTe PV market share, results in a supply gap starting in 2029 and a supply gap peak of 508 metric tons in 2036. Our work shows that having more manufacturing capacity is insufficient if tellurium is unavailable. More importantly, this work shows that fast growth in CdTe PV production can diminish the advantages of dematerialization. The estimated cumulative CdTe PV production by 2050 ranges between 929 and 2250 GWp. The findings also suggest that recycling retired solar panels can contribute to 17% of the total tellurium demand and 34% of the CdTe PV tellurium demand. Sensitivity analysis shows that expanding existing Te-rich ores does not alleviate tellurium scarcity. Alternatively, improving tellurium yield from copper electrorefining is a more efficient mitigation approach. The system dynamic approach outlined in this study provides a better perspective on the status of various critical metal supply chains, ultimately leading to sustainable materials management and increasing CdTe production.