Investigating the Geothermal Energy Potential and Permafrost Structure in Nunavut with Magnetotelluric Data
Notice bibliographique
Résumé
To reduce reliance on fossil fuels, Canada is investigating the development of alternative energy systems that have lower carbon emissions than those currently in use. This is particularly important for communities in the Canadian Arctic, where the vast majority of electricity and heat is currently generated by burning fossil fuels. Geothermal energy systems have the potential to provide an alternate source of heat in this region, and their feasibility in remote Northern settlements is being investigated. Knowledge of subsurface rock type and groundwater conditions is an essential part of exploration for geothermal energy. In summer 2023 a group from the University of Alberta collected magnetotelluric (MT) data at two communities in Nunavut to investigate the subsurface conditions. The MT method can determine the subsurface electrical resistivity to depths of several kilometers. Resistivity is a parameter that is sensitive to the temperature and porosity of the subsurface, and to the quantity and salinity of groundwater. At Cambridge Bay, MT data was collected at 26 stations in July 2023 in an east-west array that covered an area of 17 x 8 km. At Resolute Bay, 33 stations were recorded in August 2023 in a region that was 8 x 5 km. Data from an additional 11 stations were previously recorded at Resolute Bay in 2022. The time series data were processed to give frequency domain data in the frequency band 500 – 0.001 Hz. The data were then used to generate models of subsurface resistivity using a combination of 1-D and 3-D inversion methods. Interpretation of the resistivity used knowledge of subsurface temperatures and experiments on frozen / unfrozen sedimentary rocks that contained saline ground water. At Cambridge Bay the resistivity model was characterized by two layers: (1) a 100 m thick surficial layer that has a low-resistivity due to the presence of limestone saturated with partially frozen saline pore water and (2) a deeper high-resistivity layer interpreted as limestone containing low salinity pore water. Knowledge of the geothermal gradient suggests that the upper part of this surface layer was frozen and the lower part unfrozen. At Resolute Bay, the resistivity model was characterized by three layers: (1) a high-resistivity limestone layer containing partially frozen saline pore water (2) a low-resistivity layer containing unfrozen saline pore fluids, and (3) a deeper high-resistivity layer containing low salinity pore water. Porosity estimates of the subsurface below Cambridge Bay were low, indicating poor natural reservoir potential, whereas the subsurface below Resolute Bay may have greater porosity. These results also indicate that the geothermal gradients at both communities are relatively low, suggesting that direct use geothermal installations are more feasible at each location, and engineered geothermal systems (EGS) may be required to produce the reservoir characteristics required for geothermal use. The low resistivity of the 100 m thick surface layer at Cambridge Bay may have originated in the diffusion of seawater from the surface when the land surface was submerged after the retreat of the Laurentide Ice sheet. Simple 1-D diffusion modelling is consistent with the timescales and layer thickness of approximately 100 m.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».