Modeling closed-loop and open-loop geothermal energy systems for the dual utilization of energy extraction and storage

The exploration of subsurface geothermal reservoirs has gained significant attention in recent years as a sustainable solution for energy storage and extraction. These reservoirs, ranging from shallow to deep geological conditions, offer immense potential to meet the growing demand for renewable energy while reducing reliance on fossil fuels. By leveraging the Earth's natural heat or over-seasonal waste heat, geothermal systems provide a reliable and environmentally friendly energy source for heating, cooling, and electricity generation. Recent advancements in technology and improved understanding of subsurface geological conditions have expanded the scope of geothermal applications, positioning them as a vital component of the global energy transition.

In this study, various geothermal systems in porous and fractured reservoirs are modeled using flow, heat, and mass transport processes implemented in the open-source software OpenGeoSys (OGS), such as Borehole Heat Exchangers (BHEs). The performance, sustainability, and efficiency of these geothermal systems are analyzed through scenarios involving inter-seasonal multi-cycles of energy use. Additionally, surface energy utilization systems designed for low- and mediate-grade geothermal heat sources, such as geothermal heat pumps and Organic Rankine Cycle (ORC) power plants, are modeled and optimized using the open-source simulation toolkit TESPy (Thermal Engineering Systems in Python).

This work also investigates the mechanisms of interaction between subsurface and surface facilities by coupling geothermal reservoir with thermodynamic process simulation. The integrated simulations enable further optimization of the entire system. This study aims to summarize progress made in modeling geothermal systems for energy extraction and storage using OGS, while also outlining future directions for developing large-scale integrated models that incorporate other renewable energy sources.