Life-Cycle Nitrogen Trifluoride Emissions from Photovoltaics

Amorphous- and nanocrystalline-silicon thin-film photovoltaic modules are made in high-throughput manufacturing lines that necessitate quickly cleaning the reactor. Using NF(3), a potent greenhouse gas, as the cleaning agent triggered concerns as recent reports reveal that the atmospheric concentrations of this gas have increased significantly. We quantified the lifecycle emissions of NF(3) in photovoltaic (PV) manufacturing, on the basis of actual measurements at the facilities of a major producer of NF(3) and of a manufacturer of PV end-use equipment From these, we defined the best practices and technologies that are the most likely to keep worldwide atmospheric concentrations of NF(3) at very low radiative forcing levels. For the average U.S. insolation and electricity-grid conditions, the greenhouse gas (GHG) emissions from manufacturing and using NF(3) in current PV a-Si and tandem a-Si/nc-Si facilities add 2 and 7 g CO(2eq)/kWh, which can be displaced within the first 1-4 months of the PV system life.