Trade-offs of End-of-Life Strategies for Cadmium Telluride Solar Cells

Abstract

Solar generated energy is an alternative to fossil fuel generated energy. However, solar modules have a lifetime and as sales are increasing, waste of solar modules is increasing as well. Cadmium telluride solar cells consist of a material that has a high intrinsic toxicity, cadmium, and a material that is scarce, tellurium. Effective recycling of these materials is therefore needed to lower their impact on the environment. In literature, studies were found that looked at the impacts of the life cycle of CdTe solar cells of which many excluded the recycling stage. As multiple pathways exist for recycling of CdTe solar modules, it is key is to see how they compare to each other. There are a few studies that did include or assessed only a recycling stage. These assessments are all done with distinctive methods, assumptions, and boundaries, making it very hard to compare these results. In literature, a lack incompetent comparison between recycling pathways, including qualitative and quantitative aspect, was identified. The goal of this research was to find qualitative and quantitative trade-offs of potentialEnd-of-Life strategies that are able to lower environmental impacts of CdTe solar modules. By conducting harmonization on existing environmental impact data found in literature and assessing environmental impacts in a Life Cycle Assessment, the quantitative trade-offs were found. Qualitative trade-offs were found in an assessment that include maturity of technology, costs of the technology, and value of recovered material. General quantitative trade-offs that were found were that recycling lowered the environmental impacts, but energy needed for recycling had a large contribution to the remaining impacts. Additionally, the use of chemical recycle processes lowered impacts, however the chemicals that were used gave a large contribution to the impacts remaining due to extraction of chemicals and treatment of wastewater. General qualitative trade-offs could be found in the fact that high recovery values often have high costs related to them. Especially the use of chemicals does retrieve a lot of material, but I expensive. In summary, trade-offs can be found in energy and chemicals use and in costs versus value retrieved. The results of this study add knowledge on the trade-offs of each recycle strategy. This can be weighed against each other and be helpful in deciding which recycle pathways to follow when the incoming CdTe solar module waste needs to be disposed of.