AbstractSeasonal heat storage in the shallow subsurface is gaining relevance due to the increasing production of energy from renewable sources. This work presents model extensions of the code OpenGeoSys for simulating impacts of heat storages on groundwater quality. Application of the non-isothermal model is demonstrated for scenarios of heat storage in a TCE contaminated aquifer. Simulation results show slightly elevated TCE emissions due to increases in flow and solubility, but also increases in contaminant biodegradation caused by widening of the plume. Further experimental and modeling work is required for a quantitative assessment of such complex systems and process interactions.