A comparative life cycle assessment of end‐of‐life treatment pathways for photovoltaic backsheets

Abstract

In light of growing photovoltaic (PV) installation capacities around the world, and with it the increasing number of decommissioned modules, it is vital that PV waste is duly treated to recover valuable materials as well as to comply with legislative requirements. The European Union (EU) directive on Waste Electrical and Electronic Equipment and the Restriction of Hazardous Substances mandates manufacturers, retailers, and importers to collectively organise and finance the end‐of‐life (EoL) stage of electronic products in the EU. Using life cycle assessment, this study makes a comparative analysis of the environmental impacts stemming from the EoL treatment of fluorine‐free and fluorinated backsheet material present in PV modules. The 2 potential EoL treatment scenarios explored in this study are incineration and pyrolysis. In general, the life cycle assessment of fluorine‐free backsheet material shows better environmental performance than fluorinated backsheet material for both EoL scenarios. For incineration scenario, the environmental impact of fluorine‐free backsheet is evidently better than fluorinated backsheet across 11 out of 12 investigated impact categories. Similarly for pyrolysis scenario, fluorine‐free backsheets have better environmental performance than fluorinated backsheets in 8 out of 12 impact categories. Furthermore, because of the release of high amounts of hydrogen fluoride, as well as the presence of halogenated hydrocarbons and halogenated aromatics in pyrolysis products, it can be concluded that pyrolysis is not an environmentally feasible pathway for fluorinated backsheet.

Resource efficient recovery of critical and precious metals from waste silicon PV panel recycling

“…Obviously, the pyrolysis scenario is only theoretical and could be used only if recyclers were certain that no halogenated components were embodied in the PV panel. Aryan et al (2018) proved that the pyrolysis of fluorinated backsheets is unfeasible both from an economic as well as technical viewpoint. For this purpose, the study by Fraunhofer (2017) suggested the potential labelling (or marking) of PV panels by manufacturers, according to the fluorine content.…”

“…Interestingly, studies by Latunussa et al, 2016, Wambach, 2017, Aryan et al (2018) and Corcelli et al (2018) agree on the environmental significance of incinerating the halogenated plastics in the backsheet. Unfortunately, as reported by Wambach (2017), if the ‘halogen content is too high, then incineration in a specialised hazardous waste plant must be carried out’, in order to minimise the emission of potentially toxic air pollutants such as hydrogen fluoride (HF).…”

“…Detailed research on the thermal treatment of plastics in PV backsheet is presented by Fraunhofer, 2017, Aryan et al, 2018, supported by experimental results and primary industry data. Three types of backsheet have been analysed, including two fluorinated plastics (Tedlar-polyethylene terephthalate-Tedlar – TPT, and Kynar-polyethylene terephthalate-Kynar – KPK), and a fluorine-free backsheet (polyethylene terephthalate-polyethylene terephthalate-ethylene vinyl acetate – PPE).…”

“…Fraunhofer (2017) measured that the fluorine content of backsheet can be up to 9% (in weight). Aryan et al (2018) recently published an LCA of different EoL treatment pathways for PV backsheets. However, the studies by Fraunhofer (2017) and Aryan et al (2018) focused on the treatment of the backsheets and did not investigate the impact over the full life cycle of the PV panel.…”

Towards a circular supply chain for PV modules: Review of today's challenges in PV recycling, refurbishment and re‐certification

“…Recently, Wade et al presented a comprehensive decision tree (Figure ) depicting the different options for EoL management of decommissioned PV systems. A significant number of scientific studies and public reports, as well as research projects and collaborative platforms have attempted over the last years to shed light on these different EoL paths and processes, with a major focus on PV recycling technologies, high‐value material recovery, downstream EoL management models (collection‐transportation‐recycling) and life cycle analyses. So far, insights from the reported literature have been rather fragmented and somewhat one‐sided, largely focusing on PV recycling processes and relevant innovation efforts.…”