Permafrost Mitigation Solutions for Underground Thermal Energy Storage in Baker Lake, Nunavut
Student: Abra Roberta Gold
Year: 2023
Supervisors: Einar Jón Ásbjörnsson, Jasmin Raymond, Mafalda M. Miranda
Absract:
Northern communities in Canada depend on energy to survive harsh arctic and subarctic climates. Diesel fuel is their primary energy source, putting these communities in an energetically, economically, and environmentally vulnerable position. Switching from diesel to renewable energy options reduces reliance on fossil fuel and the risk of oil spills. One option is using borehole thermal energy storage (BTES). Waste heat from a diesel generator is stored underground in summer to be extracted during winter. This heat can be provided to the community via district heating. An important issue with BTES in northern Canada is permafrost. Thaw of ice rich material can damage infrastructure such as boreholes. Using permafrost thaw mitigation strategies, it may be possible to limit ground temperature changes causes by a BTES. Numerical simulations of BTES with passive (pipe, grout, VIT casing, air insulation around the upper borehole section) and active solutions (thermosyphons) to mitigate permafrost thaw were developed to address this question. The community of Baker Lake (Nunavut, Canada) is used as an example to define how to reduce ground temperature changes and elevate energy stored. The results have showed that air insulation around the upper section of the borehole and thermosyphons can reduce cyclic changes of ground temperature near the surface caused by underground energy storage.