Critical metals in strategic photovoltaic technologies: abundance versus recyclability

Research efforts have been directed toward photovoltaic technologies using abundant base metals such as copper and zinc (e.g., CZTS or more recently CZTSSe) to overcome the material constraint challenges posed by tellurium, indium, germanium and gallium in current generation technologies (e.g., CdTe, CIGS, a-Si/thin-film Si). These materials are limited in supply because they are minor byproducts of copper, zinc, lead and aluminum production and their economic production is inherently linked to that of the base metals. On the other hand, although the base metals currently are abundant, their reserves are not inexhaustible. In addition to resource availability, the main sustainability metrics for large scales of photovoltaics growth are low cost and minimum environmental impact. As photovoltaics installations grow to greatly displace traditional power generation infrastructures, recycling will play an increasingly important role in managing their end-of-life and relieving pressure on the prices of critical materials. Identifying potential issues of current technologies can help implement take-back or recycling program ahead of time. This work explores the material recycling potential of various commercial and under development photovoltaic technologies. It sheds light on a dimension of sustainability that has not been investigated before. On the basis of entropy analyses, documented by the experience of recycling electronic products, we show that recycling of some types of photovoltaic modules that are based on abundant materials could be burdened by complexity and lack of value, creating, therefore, concerns associated with both end-of life environmental impacts and resource availability. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.