Geothermal Energy Potential of Northwest Territories, Canada

Abstract

Northern Canada faces unique challenges of numerous remote communities largely separated from electrical grid systems. Thermal and power needs are typically meet by truck transported hydrocarbons, which in some cases are subject to winter ice-road conditions, including timing of seasonal freeze and break up of ice bridges that limits shipments to narrow time windows through the year. Potential to develop local energy resources can provide communities with energy sovereignty along with greater energy security. Low average air temperatures of the territory can provide a thermal advantage that increases efficiency of geothermal plants compared to warmer climate regions, which may make geothermal development more advantageous. The relative simplicity and robustness of geothermal plants also provides an advantage for development of renewable power solutions in remote communities of Arctic Canada. We examined the geothermal energy resources of the NWT, with particular focus on communities with higher resource potential. The broad area of eastern NWT underlain by the Canadian Shield has low heat flow and geothermal gradients limiting resources largely to heat pump systems, or potentially Enhanced Geothermal Systems. Some notable exceptions are geothermal potential of abandoned mines where large water filled mine tunnels allow high volume production and heat extraction. Of particular interest is the Con Mine site near the capital Yellowknife, that has been closed and is undergoing remediation. Current land use plans are to revert the surface portion of the mine site to industrial development, creating the potential to extract heat form flooded mine tunnels to provide low cost heating solutions for new building construction. Sedimentary basins of the western NWT have inherently low thermal conductivity and act as thermal blankets trapping radiogenic heat. These regions also have higher heat generation than much of Canada. Drilling by the petroleum industry has defined regions of high temperature geothermal resources at depths associated with known aquifer units, suggesting potential for sufficient fluids production rates to produce net power at surface along with associated direct heat use. Potential issues with scaling associated with brines from these levels could cause some technical challenges however. Further research on potential hot sedimentary aquifers could help focus potential exploration targets for geothermal systems. An underlying challenge for further geothermal development in the NWT is the variable degree of permafrost thickness, ranging from discontinuous in the southern portion of the territory to several hundreds of meters in the north. Geothermal well design will have to account for permafrost to ensure production of hot fluids to surface does not induce melting.