Analyzing clogging and scaling processes in carbonate and siliciclastic ATES systems based on column and batch experiments

Aquifer thermal energy storage (ATES) is one of the main types of geo-storage concepts aimed at an efficient energy supply and for achieving a low-carbon energy balance. In ATES, thermal energy is stored underground for later use; for instance, by intentionally injecting warm water - heated up by excess heat energy of industry and commerce - into the aquifer, and recovering it later for heating purposes, e.g., during the winter period. However, a significant number of ATES projects suffer from operational and maintenance issues or failures. Mineral precipitation (scaling) and flocculation, or microbial growth are major risks for ATES. By reducing the permeability in reservoirs, these processes threaten medium- to long-term operational reliability.  

The BMBF-funded research project ‘UnClog-ATES’ comprehensively investigates clogging and scaling in two typical reservoirs for ATES systems (siliciclastic sediments and carbonate-bearing sediments) which are widely distributed and exhibit different reactivity with respect to temperature and hydrochemical changes. Laboratory-scale flow-through column experiments as well as batch reactor experiments will be performed to simulate transport under representative ATES conditions (pressure, temperature, hydraulics, and chemical composition). Additionally, countermeasures (e.g., scaling inhibitors, acids, or CO₂) will be investigated to maximize the potential of ATES in the future. Finally, based on numerical reactive solute transport models, a catalog of criteria for users and decision-makers will be created to facilitate an initial site assessment in order to minimize the operational risk of ATES at this level.