HGS RESEARCH HIGHLIGHT – Geothermal Energy Potential of Active Northern Underground Mines: Designing a System Relying on Mine Water
Alvarado, E. J., Raymond, J., Therrien, R., Comeau, F.-A., & Carreau, M. (2022). Geothermal Energy Potential of Active Northern Underground Mines: Designing a System Relying on Mine Water. In Mine Water and the Environment. Springer Science and Business Media LLC. https://doi.org/10.1007/s10230-022-00900-8
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A new article published by researchers at Quebec’s National Institute for Scientific Research (INRS) (and co-authored by Aquanty co-founder and board member Dr. Rene Therrien) explores the viability of using geothermal energy as an alternative energy source for a remote mine in northern Quebec using HydroGeoSphere. This is a interesting study because the authors propose to couple a geothermal heat pump system to existing dewatering system for this deep underground mine.
The current study is mostly focused on deep bedrock, saturated groundwater flow, with the model extending 2km down from ground surface. The model was calibrated against drawdown levels and water temperature for an initial 6-year period from 2013-2019 (i.e. the first six years of mine operations). Subsequently, flow and heat transport were modelled using HGS for the years 2020-2031 (i.e. the estimated remaining life of mining operations). Dewatering wells at various depths were represented as nodal fluxes within the numerical model, with the modelled temperature of these waters being used to evaluate the feasibility of geothermal energy production.
The modelling results of this study indicate that a geothermal heat pump system coupled with the existing mine dewatering system would be well suited to the Éléonore mine, with the potential to supply up to 45% of the heating demands for underground operations, with significant reductions in greenhouse gas emissions.
This study illustrates HydroGeoSphere’s utility as a tool for evaluating the potential of geothermal energy, and not only in underground mine settings. HGS can implicitly simulate thermal energy throughout hydrologic systems (including density driven transport effects), and it’s also able to model extremely complex geological systems with spatially and temporally varying material properties, with or without the presence of discrete fractures, and with the ability to represent mine infrastructure as discrete features within the model.
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Abstract:
Mines in northern regions must heat underground workings, surface buildings, or process water due to frigid weather conditions. Mining companies commonly use fossil fuels for heating, which creates environmental challenges. An eco-conscious alternative, based on local resources and low electricity consumption, is the use of geothermal energy from the mine dewatering system. The Éléonore mine, an active underground mine located in a remote area in northern Québec (Canada), was selected as a case study. The geothermal resource was characterized to design a geothermal heat pump system (GHPS) adapted to mining operations. The energy balance was calculated to establish the heating energy requirements of the mine. Subsequently, the physicochemical properties of the water from different sampling points along the dewatering system were analyzed. Finally, a preliminary GHPS was designed to assess the amount of geothermal energy that can be extracted from the dewatering system of the mine. Under current conditions, a GHPS installed at the exit of the dewatering system could provide 39% of the 26.6 GWh/yr needed to heat the underground workings, reducing heating costs by 33% and greenhouse gas emissions by 1993 t/yr. A hydrogeological numerical model developed for the mine further suggests that a GHPS is sustainable throughout the life of the mine. Thus, this research indicates that, with adequate assessment, GHPSs have the potential to heat active mining operations and contribute to their energy needs in an environmental, affordable, and constant manner.