system Performance
ATES systems around the world
Examples of ATES systems in operation around the world include the thermal energy storage system in Oslo Airport, with 18 wells each extending up to 45 m below the surface. The water injected through these wells spreads out over hundreds of metres in lateral extent (Royal Society Report, 2026).
An ATES system in Neubrandenburg stores about 12 MWh per annum at high temperature up to 65 – 80°C, while a low-temperature shallower aquifer system in Berlin stores about 2,500 MWh with water at temperatures of 30 – 60°C (Royal Society Report, 2026).
Typical scales of the system
With water injection rates of order 1 – 100 kg/s in a single well, the thermal energy storage over a season may be of order 1 – 10 GWh, involving the storage of about 105 – 106 m3 of heated water (Royal Society Report, 2026).
The UK hosts numerous shallow subsurface aquifers, representing an extremely effective resource to store very large quantities of waste heat. Given that the UK’s winter heating load may be as large as 100 – 150 GW, the development of several hundred thermal energy storage systems could provide the underpinning thermal energy for ~ 5 – 10% of the total heating load through district heat networks across the country, especially in highly populated areas with large thermal energy demand.
Seasonal operation of a double-well ATES system (from Lepinay and Woods)
Estimated performance of an ATES system
Our calculations for typical systems suggest that using a double well ATES system can lead to a 5 – 15% decrease in the electricity usage of the heat pump in the winter, compared to using a heat source at the original ambient temperature of the aquifer (Lepinay and Woods 2025).
The performance of the system over the first few cycles of operation depends on its initial condition. If the system is initially operated in the summer, then it can provide an average reduction of about 10% in electricity usage for winter heating over 20 years. If the system is initially operated in the winter, then the average reduction in electricity usage for winter heating is estimated to be around 7% (Lepinay and Woods 2025).
Our model indicates that after 2 – 3 cycles, over 90% of the thermal energy injected into the hot reservoir is recovered in the extracted fluid (Lepinay and Woods 2025).