TY - THES

T1 - Solar Heat Geo Battery

AU - Kopeinig, Clara Maria

N1 - no embargo

PY - 2024

Y1 - 2024

N2 - With the significant development of renewable energy sources such as solar and wind power, energy systems are increasingly challenged by the mismatch between energy supply and demand. Photovoltaic systems, for example, often generate excess energy during peak sunshine hours, particularly in summer, which do not match with the periods of highest energy demand. This intermittent generation creates a need for robust thermal energy storage that can store the surplus of energy and release it as needed. Several types of underground thermal energy storage systems are currently being used to meet energy storage needs. The main underground thermal energy storage system technologies include aquifer thermal energy storage, borehole thermal energy storage and pit thermal energy storage. A significant gap remains when it comes to developing a controlled approach to thermal energy storage within aquifers that can store heat without fluid injection, where a geothermal reservoir is artificially created by heating it using renewable energy. To address this gap, this study investigated the creation of an artificially heated geothermal reservoir by installing a solar powered resistive heating rod. In this approach, heat is stored in situ within the aquifer, allowing for stable and localized storage. Using OpenGeoSys, a numerical model was developed to simulate heat transfer in a 2D subsurface environment, capturing both conduction and convection mechanisms. Key parameters have been subject to a sensitivity analysis, including permeability, porosity, groundwater flow velocity, thermal dispersivity and the specific heat capacity and thermal conductivity of sandstone to evaluate their impact on heat propagation, storage efficiency and thermal plume development. This modelling effort provides insight into the feasibility of storing thermal energy in aquifers heated by a heating rod and provides a basis for designing systems capable of efficiently recovering stored thermal energy, particularly in seasonal storage applications.

AB - With the significant development of renewable energy sources such as solar and wind power, energy systems are increasingly challenged by the mismatch between energy supply and demand. Photovoltaic systems, for example, often generate excess energy during peak sunshine hours, particularly in summer, which do not match with the periods of highest energy demand. This intermittent generation creates a need for robust thermal energy storage that can store the surplus of energy and release it as needed. Several types of underground thermal energy storage systems are currently being used to meet energy storage needs. The main underground thermal energy storage system technologies include aquifer thermal energy storage, borehole thermal energy storage and pit thermal energy storage. A significant gap remains when it comes to developing a controlled approach to thermal energy storage within aquifers that can store heat without fluid injection, where a geothermal reservoir is artificially created by heating it using renewable energy. To address this gap, this study investigated the creation of an artificially heated geothermal reservoir by installing a solar powered resistive heating rod. In this approach, heat is stored in situ within the aquifer, allowing for stable and localized storage. Using OpenGeoSys, a numerical model was developed to simulate heat transfer in a 2D subsurface environment, capturing both conduction and convection mechanisms. Key parameters have been subject to a sensitivity analysis, including permeability, porosity, groundwater flow velocity, thermal dispersivity and the specific heat capacity and thermal conductivity of sandstone to evaluate their impact on heat propagation, storage efficiency and thermal plume development. This modelling effort provides insight into the feasibility of storing thermal energy in aquifers heated by a heating rod and provides a basis for designing systems capable of efficiently recovering stored thermal energy, particularly in seasonal storage applications.

KW - Thermal Energy Storage

KW - TES

KW - Underground Thermal Energy Storage

KW - UTES

KW - Geothermal Energy

KW - Thermal Energy Storage

KW - TES

KW - Underground Thermal Energy Storage

KW - UTES

KW - Geothermal Energy

U2 - 10.34901/mul.pub.2025.017

DO - 10.34901/mul.pub.2025.017

M3 - Master's Thesis

ER -