Geothermal Systems Performance and Environmental Impacts

The use of fossil fuels for heating and cooling purposes is plagued by problems including environmental impacts, unsustainable production, and increased greenhouse gas production. This had led to a worldwide interest in developing sustainable sources of energy. One such energy is ground source heat which is the ubiquitous low-enthalpy heat found in the shallow subsurface. Vertical ground source heat pumps (GSHPs) can be used to extract or inject subsurface heat by installing borehole that circulate an antifreeze-based carrier fluid which is cooled or heated through the subsurface. Although GSHPs have many advantages, they might develop thermal subsurface plumes, which can affect the efficiency of the system and other subsurface infrastructures. In the present research, the effect of a multi-borehole vertical GSHP system located in various locations in Canada was examined. To do so, a three-dimensional model was developed in FEFLOW that simulated a hypothetical GSHP system in different Canadian climates. Consequently, the resulting thermal plumes were studied and a sensitivity analysis was conducted to determine the effect of different groundwater and soil parameters on the development and movement of thermal plumes.