| Title | Ultra-High-Temperature Underground Thermal Energy Storage (UHT-UTES) for Large-scale, Inter-seasonal Electricity Storage |
|---|---|
| Authors | Ruixiao Liu, Matthew D. Jackson, Gary Hampson, Carl Jacquemyn, Meissam Bahlali |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | Low-temperature (LT-) and high-temperature underground thermal energy storage (HT-UTES) are used to provide heating and cooling. Here, we investigate the potential for ultra-high temperature underground thermal energy storage (UHT-UTES) to balance seasonal fluctuations in electricity supply and demand. During periods of excess supply, groundwater is pumped from naturally porous, permeable underground reservoirs at depths > 500 m, heated to high temperature (>150°C) and pumped back underground where it is stored. When demand exceeds renewable supply, the high temperature water is pumped back to surface and used to generate electricity. UHT-UTES offers several potential advantages over comparable underground storage technologies such as hydrogen storage: the surface facilities are conventional, comprising boilers and turbines, and expertise can be shared from hydrothermal electricity production. The technology can utilise deep saline aquifers and end-of-life hydrocarbon reservoirs which are geographically widespread and offer large storage and flow capacity. Despite the potential for UHT-UTES, significant uncertainties remain concerning storage efficiency when the stored water temperature is significantly higher than the ambient reservoir temperature. There are also potential risks to sustainable operation, such as scaling and associated loss of storage and flow capacity, and/or the potential for rock weakening and seismicity. This study reports the results of numerical modelling to determine key controls on the storage efficiency of UHT-UTES considering a range of operational storage temperatures, reservoir geological settings and heterogeneities. |