Direct Te Mining: Resource Availability and Impact on CdTe PV Life-Cycle Assessments

The availability of Te is constrained by the production rate of its main parent compound (copper) and a debate is going on related to the potential supply of Te for very large scale CdTe PV deployment. However, recent investigations point to the existence of Te-rich ores in several places of the world that are likely to allow economic recovery of Te, independently of the production of copper. Consequently, direct mining of Te from such ores may potentially increase the environmental burden of mining and smelting operations in the life cycle of CdTe PV systems. In conventional CdTe life-cycle assessments (LCA), one allocates the environmental impacts of mining and smelting to all the co-products on the basis of products’ volumes or economic values. Since Te in typical copper sulfide ores is in concentrations of about 1.5 ppm (global average) whereas the concentration of Cu in the same is about 6,000 ppm (0.6%), very little of the environmental impacts of mining and smelting are allocated to the production of Te. If economic value is used in the allocation, then ~0.7% of the emissions are assigned to the production of Te. In the case of direct Te mining the allocation of environmental impacts to Te assumes a larger share or the total impacts because the concentration of tellurium and the economic value are comparable to that of the co-products. An assessment of 5 project cases devoted to direct-mined tellurium is used to show how the, energy and chemical inventories in direct Te mining compares to those of the Te recovery from Cu production circuits. Other factors that influence the impacts of direct Te mining include the presence of co-products (e.g., gold), the relative contribution of Te to the life cycle cumulative energy demand of CdTe PV, the proportion of directly mined Te content relative to Cu bi-product content in the Te supply chain, and end-of-life CdTe PV recycling to mitigate the need for Te from mining.