Environmental and health impacts of heat transfer fluids (HTFs)

Abstract

Thermo Solar Systems are growing significantly around the world. Although they are thought to be clean, the analysis of its life cycle evidence a negative impact on the environment, due to unvoluntary spillages of heat fluid transfer (HTF). To know the risk of HTF spills for human health and environment, we selected human cell lines and toxicological model organisms to evaluate both aspects. In concrete, we selected two non-transformed human cell lines of fibroblasts and hepatocytes; Allivibrio fisherii, Dictyosphaerium chlorelloides, Emiliana huxleyi and Artemia salina. Using standardized toxicological tests, we studied the effect of HTF under two scenarios: 1) exposure cells to concentrations on the range from 0.1 to 15 μg/L for short periods (from 30 min to 72 h) and 2) the same concentrations for 20 days. Additionally, we explored the toxic effect of two different HTF samples: commercial and thermal degraded HTF (used). Results proved that commercial is less toxic than used and that microalgae was extremely sensitive (IC50 around 3.5 μg/L) following of Allivibrio fisherii (IC50 around 200 μg/L), human cell lines (IC50 around 1000 μg/L) and crustaceans (IC50 2000 μg/L). The particularities of cell wall composition and the metabolic specialization justify the differences. Furthermore, a very interesting result was that exposure for 20 days produced greater damage than the same dose for periods of 72 h in all the cell types studied. Our results suggest that HTF spillages have a bigger environmental impact than expected, which thermosolar plants are not as environmentally friendly as previously thought