| Title | AGES Subsurface Thermal Batteries – Innovative Subsurface Thermal Energy Storage for Enhanced Network Stability and Profitability |
|---|---|
| Authors | Hervé Lautrette Claire Bossennec Régis Studer Laurent Gerbaud Marc Blaizot |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | High-temperature thermal energy storage in the subsurface offers a technically robust solution for enhancing the flexibility and reliability of heat and power systems. The AGES (Advanced Geothermal Energy Storage) concept employs geothermal probes to use the subsurface as a thermal reservoir through closed loops, storing excess heat during periods of high production (solar or industrial fatal heat) and releasing it during peak consumption. AGES follows an integrated, multi-energy design focused on optimizing thermal performance while maintaining integrity. It supports scalable, low-carbon energy deployment using renewable and recovered heat sources. The system minimizes surface impact, has low reliance on critical raw materials, and is based on commercially available technologies. Its modular architecture enables deployment in over 95% of geological contexts. One of the primary technical challenges involves managing large thermal variations over short time periods, which can induce mechanical stresses affecting rock stability and reservoir permeability. AGES addresses this through geomechanical analysis and integrated monitoring to ensure long-term system stability. To demonstrate techno-economic viability—particularly via the Levelized Cost of Energy (LCOE)—AGES develops its own subsurface systems to maintain control over capital costs. This approach challenges the assumption that closed-loop systems are inherently cost-prohibitive. A core objective is to reduce drilling costs for depths beyond 500 meters by a factor of at least three. The system enables the storage and controlled delivery of over 50 GWh/year at temperatures above 90 °C and depths from 30 to more than 1000 meters, contributing to decarbonized, dispatchable energy infrastructure. |