Mapping the low enthalpy geothermal potential of shallow Quaternary aquifers in Finland

Abstract

Background: EU member states have concluded an agreement that renewable energy will cover 20% of the total energy production by 2020. To achieve this target, it is essential to investigate all possibilities for renewable energy production. We investigated whether groundwater could provide a shallow geothermal energy resource, and to what extent it could meet the demands for heating buildings in Finland. Our research focused on classified aquifers, namely, groundwater areas that are zoned for urban or industrial use. Methods: The heating potential of Finnish aquifers was estimated based on the flux, temperature and heat capacity of groundwater and the efficiency of heat pumps. The design power of residential buildings was then simulated. Finally, the design power was divided by the groundwater power to determine the ability of groundwater to heat buildings. Results: Approximately 56,500 ha of Finnish aquifers are zoned for urban or industrial land use. These aquifers contain 40 to 45 MW of power. In total, 55 to 60 MW of the heat load could be utilised with heat pumps, meaning that 25% to 40% of annually constructed residential buildings could be heated utilising groundwater in Finland. Conclusions: There are several hundred sites in Finland where groundwater could be used for energy utilisation, and groundwater could thus be a significant source of local renewable energy. However, because of geological and geographical factors, groundwater cannot be considered as a nationwide energy source. Future research should define the area-specific limiting factors for groundwater energy use.