Evaluating short-circularity pathways for photovoltaic glass through life cycle assessment: Cullet recycling versus whole-glass reuse
Tamal Chowdhury, Mohammad Dehghanimadvar, Nathan L. Chang, Richard Corkish
Abstract
The photovoltaic (PV) industry has experienced unprecedented growth due to the global energy transition. As this transition continues, PV industries will face several challenges. One significant challenge is the production of substantial amounts of PV waste. A large portion of this waste will come from glass, which constitutes a significant share of PV modules by weight. Moreover, the production of this glass requires substantial amounts of energy and materials, while also generating emissions. One potential way to address these materials, energy, emission, and waste issues, at least partially, is through recycling. A review of current literature suggests that the reintroduction of recovered PV glass into the production of new PV glass has been largely overlooked. Moreover, existing studies predominantly focus on cullet-based glass recycling, while the reintroduction of recovered intact PV glass into new PV modules remains largely unexplored. Therefore, this study addresses this gap by analyzing short-circularity pathways with a particular focus on the direct reuse of intact PV glass. Several scenarios have been evaluated, including the reintroduction of PV glass cullet and the reuse of recovered whole PV glass in new modules. These scenarios are compared with the base case, which involves producing PV glass without using any external cullet. A life cycle analysis was performed, revealing that although introducing 30% and 90% external cullet in PV glass making can reduce the global warming impact (GWP) associated with glass production by 23% (Cases 1A, 1C, and 1E) and 71% (Cases 1B, 1D, and 1F), respectively, the recovery process of external cullet makes the overall impact higher. The solvent process was the main contributor to the environmental impact of solvent-based cullet recovery, accounting for about 51% of the total GWP. The overall impact from the glass production process can be reduced by 41% after reusing 90% solvent. Recovering old, whole PV glass is highly recommended as it eliminates the GWP associated with glass production and results in 68% less fossil depletion, 74% less metal depletion, and 91% less water depletion compared to the base case. However, the recovery of old, intact PV glass has a GWP, estimated at around 245 kg CO 2 -eq per tonne, with transportation contributing more than 80% of the total impact. • First life cycle assessment study comparing intact photovoltaic (PV) glass reuse and cullet-based recycling routes. • Direct reuse of whole PV glass delivers higher environmental benefits than cullet recycling. • While using external cullet reduces the global warming potential (GWP) of glass production, cullet recovery processes can partially offset these environmental benefits. • Solvent use and PV waste transport are the main contributors to increased GWP in cullet recovery, while solvent reuse reduces the solvent-related GWP. • Reusing intact PV glass lowers GWP and reduces fossil, metal, and water depletion impacts.