Identification and econometric assessment of high-criticality byproduct metals for clean energy applications

Population growth and industrial development have led to an ever-increasing demand for energy since the beginning of industrial evolution. As society faces threats from climate change, the need for clean and reliable energy... [ view full abstract ]

Population growth and industrial development have led to an ever-increasing demand for energy since the beginning of industrial evolution. As society faces threats from climate change, the need for clean and reliable energy has become a necessity in order to mitigate these effects for future generations. Many current and emerging clean energy applications rely on a diverse use of metals, especially minor metals, such as gallium and indium required in copper indium gallium selenide (CIGS) photovoltaic (PV) cell systems and cadmium and tellurium in CdTe thin film PV cells. These metals are often produced mostly as byproducts of other base metals (carriers). Researchers have argued that byproducts in metal production create complex linkages between multiple metal systems, and the connection with carrier metals may cause the supply of byproduct metals to be limited by the market dynamics of carriers.

While many studies have attempted to evaluate the future availability of certain byproduct metals, the field lacks a comprehensive criticality assessment of byproduct metals. In this paper we perform such a criticality assessment based on characteristics essential to byproduct markets, which allows us to classify over 40 carrier-byproduct metal pairs into 5 clusters based on metrics of value and supply fraction. From there we develop an econometric framework to assess supply elasticity of byproduct metals in the high-criticality cluster and perform case studies on zinc-indium and copper-selenium systems. It is found that supply elasticity of indium and selenium are 0.10 and 0.03, respectively, both exhibiting strong inelastic behavior. While the common belief that byproduct supply is limited by carriers is true in the case of zinc-indium system, we find causes from the byproduct market itself which leads to price inelasticity of supply of selenium. We also make comparisons of current supply and supply potential for metals pairs with high or medium criticality, which could serve as an first screening of criticality assessments on these metals. The proposed modelling strategies are recommended to serve as starting points for further researches on corresponding byproduct metal systems.