Cradle-to-gate life cycle assessment of the dry etching step in the manufacturing of photovoltaic cells
A new photovoltaic silicon crystalline solar cell dry chemical etching process (DCEP) is developed. It is an alternative to the current State-of-the-Art (SoA) wet chemical etching process (WCEP), associated with relatively large environmental loadings in the form of high water consumption and emissions of greenhouse gases with high Global Warming Potential (GWP). In order to compare the environmental impacts of DCEP to the corresponding impacts from WCEP, a comparative attributional life cycle assessment (LCA) is conducted. From the LCA it can be concluded that the DCEP will lead to 86% reduction in water consumption compared to WCEP (acidic), and 89% reduction compared to WCEP (alkaline). The emissions of greenhouse gases, as expressed by the GWP100 indicator of the etching step, are also reduced with 63% and 20% respectively, when compared with current SoA acidic and alkaline WCEP. The toxicity impacts are also assessed to be lower for the DCEP compared to WCEP technologies, although the uncertainty is relatively high for the applied toxicity indicators. All in all, DCEP can reduce the CO2eq emissions of solar photovoltaic systems production by 5–10%.