Shallow and deep geothermal energy potential in low heat flow/cold climate environment: northern Québec, Canada, case study

Northern Québec, a large and cold climate territory located north of the 49th parallel, has low average heat flow density (40 ± 9 mW/m²) typical of the Canadian Shield. The lack of the thermal blanket otherwise provided by sediments in the platform of southern Québec results in deep drilling requirements for potential mining heat (80 °C at some 5 km). Drilling doublet or triplet well systems at such depths into low-enthalpy granitic rocks would be expensive; however, in some cases of heat flow higher by one standard deviation of the mean and fracked permeability allowing flow rates >30 kg/s may make this heat useable in the future. Other options in providing heat are more likely to be applied earlier. These would include shallow geothermal energy use with heat pumps in granites by placement of artificial heat exchanges by directional loop drilling. These systems may have promise in Northern Québec due to its very cold climate and extremely high energy cost based on diesel oil heating for remote communities and mining areas. Findings show that recent industrial age climatic warming increased the mean underground temperatures in the upper circa couple hundred meters. This has resulted in temperature gains and energy ground storage.