Advanced geothermal energy storage systems by repurposing existing oil and gas wells II: a full-scale experimental and numerical investigation

This study focuses on the investigation of thermal energy storage characteristics of an Advanced Geothermal Energy Storage (AGES) system in a low-temperature sedimentary formation in the Illinois basin. An AGES system operates by injection of heat collected from various sources into an existing well to create an artificial and sustainable geothermal reservoir to be extracted at a later time. A systematic preliminary data analysis and interpretation pertaining to existing wells were used to probe thermal energy storage properties of the subsurface formations. A full-scale field test was performed for an advanced delineation of the subsurface thermal processes. Results from the field test were used to calibrate a two-dimensional axisymmetric numerical model for a single push/pull well. Various operational schemes are simulated for using the validated numerical model. The results indicated that the energy storage efficiency may reach up to 82% and the geothermal extraction system can generate an electrical power of 5.74 MW in five years for a simultaneous monthly injection and production scheme with an initial 90 days charging period. The proposed system, benefitting from existing infrastructure, offers an economical and environmental approach for thermal storage with high storage efficiency. 2022, The Authors. All rights reserved.