Recovery of valuable materials from end-of-life thin-film photovoltaic panels: environmental impact assessment of different management options

摘要

The present study deals with the management of end-of-life copper indium gallium selenide (CIGS) and cadmium telluride (CdTe) thin-film photovoltaic (PV) panels. We quantitatively compare the impacts and environmental weak points of the recycling processes of such panels, and their disposal in a landfill site. Two scenarios of recycling are considered: conventional and innovative. In the conventional recycling, the modules are crushed, glass is recovered, ethylene-vinyl acetate (EVA) is sent to thermal treatment to gain energy and the residual material is disposed of in a landfill site. Conversely, the innovative recycling option goes beyond conventional technologies and it allows to recover also selenium, indium and gallium from the CIGS panels, and tellurium from the CdTe panels. The potential impacts on the environment are similar for the conventional recycling processes of both the typologies of PV panels. Conversely, the innovative recycling of the CdTe panels creates a net production of environmental credits thanks to the recovery of valuable materials. The innovative recycling of CIGS panels has a higher impact than the recycling of CdTe panels (e.g. 2.5 vs 0.7 kg CO_2-eq., respectively, for global warming potential). In any case, the disposal of end-of-life panels is not advantageous for the environment according to life cycle assessment. Data obtained with the recycling processes currently available suggest that the innovative recycling is environmentally beneficial only for the CdTe panels, due to the very low content of valuable elements in the CIGS panels. More effort should be directed to the development of a pre-treatment that can effectively concentrate the valuable elements. Overall, the results of this study give a quantitative basis to support the recycling of PV panels and the recovery of secondary raw materials like tellurium, indium, gallium and selenium.