Geothermal Potential of the Recent Sundhnúkur Dikes on the Reykjanes Peninsula

Sammanfattning

Geothermal energy is an attractive way of energy production where it can be achieved. Iceland ranks among the world’s leaders in its utilization. Svartsengi, a geothermal powerplant on the Reykjanes Peninsula in SW-Iceland, has produced electricity and hot water for a few decades. The recent Sundhnúkur dike intrusions/eruptions close to Svartsengi have now created new opportunities for geothermal development. This thesis assesses the scale and persistence of the newly added heat and its implications for siting and timing future development near Svartsengi. Geothermal prospects associated with the recent Sundhnúkur dike sequence on the Reykjanes Peninsula are evaluated to learn the magnitude, footprint, and lifetime of intrusion-driven heat. A 2-D Finite-Element heat transfer model integrates conductive heat transfer with Darcy advection in a permeable basaltic crust, following the observed intrusion timeline. Boundary conditions fixed 5 °C at the surface and 500 °C at 5 km depth; dikes are initialized at 1240 °C, and the system commenced from 30 years prior to 50 years after the final intrusion. Fifteen years post emplacement, thermal anomalies remain discrete and centered around the dikes. By 30 years they broaden and coalesce while peak amplitudes decline. Depth profiles show excess temperatures of 15–20 °C at 500–750 m, increasing to 40–60 °C at 1000m and 75–85 °C at 2000– 3000 m depth. Warming is strongest within less than 40 m laterally of dikes and persists longest across narrow gaps, indicating proximity and spacing as primary controls. Based on the findings of this thesis, wells drilled into this area for geothermal exploration should be drilled after 15-20 years and sited as close as safely practicable (0-40 m) to the widest dikes at the shallowest depth meeting this threshold. Main limitations of the model are the 2-D geometry, homogenous crust and omission of the two most recent intrusions.