Fate and transport evaluation of potential leaching and fire risks from CdTe PV

Fate and transport analysis has been performed to evaluate potential exposures to cadmium (Cd) from cadmium telluride (CdTe) photovoltaics (PV) for non-routine circumstances (rainwater leaching from broken modules and emissions from fire). The analysis considers Cd transport from ground mount and roof mount systems via leaching, and from roof mount systems via fire and subsequent leaching. Fate and transport of Cd to soil from broken modules is based primarily on leachability, soil/soil-water partitioning coefficient, and annual rainfall. Subsequent migration to ambient air as windblown dust is dependent on both the particulate emission flux and on ambient air dispersion as modeled with a screening Gaussian plume dispersion model. Migration to groundwater is evaluated with a dilution-attenuation factor approach, and is dependent on leachability, infiltration rate, and source size. Fate and transport analysis of emissions from fire considers emissions to ambient air and transport to soil and groundwater from entrainment in water used to extinguish the fire. Fate and transport to air is dependent on the roof mount system size, Cd fire related emission rate, heat release rate, and ambient air dispersion as modeled with a screening Gaussian plume dispersion model. Fate and transport to water is dependent on the same factors that determine leaching to soil and groundwater described above. Using these modeling approaches, the relevant media-specific exposure point concentrations and/or daily intakes are estimated and compared to conservative health screening levels to evaluate potential health impacts to onsite and offsite receptors. It is concluded that potential exposures to Cd from rainwater leaching of broken modules and emissions from a fire are highly unlikely to pose a potential health risk to residents, workers, consumers, or emergency responders.