HYDROLOGICAL AND THERMAL STUDY OF AN ABANDONED UNDERGROUND COAL MINE AS-029 AS A RESERVOIR FOR GROUND SOURCE HEAT PUMPS, ATHENS, OH

Ground source heat pumps (GSHPs) have been used for heating and cooling applications in areas where the thermal gradients are normal. Unlike conventional heating and cooling systems, ground source heat pumps rely on ground or underground water temperatures which are more constant than air temperature. Abandoned underground coal mines (AUMs) have been used as heat exchangers for ground source heat pumps in countries such as Nova Scotia, Netherlands and states like Pennsylvania. Ohio has around 147 abandoned underground mines located close to towns and with sufficient water and heat available in the groundwater for heat exchange using ground source heat pumps.

This project focuses on characterizing the potential of AUM AS-029 located in Athens, Ohio, as a reservoir for GSHP technology. This study is investigating the hydrogeological parameters and thermal response of the mine. Sensors have been installed in three wells surrounding the mine to collect temperature, pressure and hydraulic head data. A numerical finite difference model (MODFLOW) will be done using the information gathered from the monitoring of water heads in the wells, the stratigraphy of the rocks overlying and underlying the mine, soil types, and the data for precipitation, infiltration, and evapotranspiration. Results from this modeling work will include the groundwater velocities and the amount of water flowing through the mine. Water temperature will be simulated using the heat transfer equations throughout the overburden, the stratigraphy and topography of the mined area. Combination of the groundwater flow and the heat transfer model will allow to determine the thermal regime in the mine after exchange of heat with heat pumps.