Work

Role of high-temperature reservoir thermal energy storage during discharge in enhancing steady-state grid stability

Year: 2026

Type: article

Abstract: The aim of this study is to determine the mechanisms governing reservoir thermal energy storage (RTES) performance and its contribution to grid stability, via a comprehensive numerical analysis. A framework is proposed integrating thermal-hydraulic coupled RTES simulation and power-grid modeling based on linearized AC optimal power flow (LPAC). Using this framework, RTES’s grid stabilization performance is examined under different fluid injection conditions, storage and production schedules, geological conditions, and well configurations. Results indicate that raising hot fluid injection temperature during storage considerably improves production temperature and electric power. A high fluid injection rate during both storage and production yields the highest real-time electric power. To simultaneously achieve elevated production temperature and cumulative generated electricity, a balanced strategy involving extended storage and production duration is recommended. With the geothermal gradient growing from 25 °C/km to 40 °C/km, after-10-year electric power improves by 14.09%. The effect of reservoir hydraulic properties depends on operation duration. For long-term operation, as reservoir permeability increases, end-of-cycle electric power rises first and then drops. Increasing well distance from 100 m to 400 m raises after-10-year electric power by 143.80%. Multi-well RTES can substantially enhance production temperature and electricity generation while improving economic performance modestly. Applying the developed framework to the ACTIVSg2000 synthetic Texas grid under a 5%-stressed summer demand shows that incorporating RTES consistently improves both the voltage stability index (VSI) and line stability index (LSI). The configuration that delivers the highest electric power provides the greatest benefit: An eight-well RTES system cuts annual load shedding by 76% (to 87MWh).

Source: Applied Energy

DOI: 10.1016/j.apenergy.2026.128937

Authors: Sai Liu, Pin-Chun Cho, Shuvajit Bhattacharya, Erhan Kutanoglu

Institutions: Bureau of Economic Geology, The University of Texas at Austin

Language: English

Topic: Geothermal Energy Systems and Applications

Subfield: Renewable Energy, Sustainability and the Environment

Field: Energy

Domain: Physical Sciences

SDGs: Affordable and clean energy, Industry, innovation and infrastructure, Climate action

Open Access status: hybrid

Estimated APC paid: $4,430