Energy storage, particularly through pumped hydropower systems (PHS), is crucial for stabilizing renewable energy grids, but its implementation in former lignite mines may pose hydrogeochemical risks due to potential groundwater contamination from pyrite oxidation. A study using reaction path modelling found that, at two European sites, the impacts on water quality from PHS operations were minimal due to natural buffering, dilution processes and other site-specific factors.

https://link.springer.com/article/10.1007/s12665-025-12198-0