The deep geothermal energy potential of Kalmar and Nybro municipalities

The potential for enhanced geothermal energy production in the Kalmar and Nybro municipalities is investigated by reviewing existing data on the regional geothermal gradient and the extent of fracture zones with depth of the crystalline crust in the research area. Existing geophysical and hydrological models along with bedrock maps and results of earlier studies in the nearby region are integrated in this report. The geothermal gradient in the Kalmar-Nybro area is currently not quantified, but proximal measurements indicate that the temperature is not likely to increase significantly more than 16-17°C/km considering local bedrock properties. Target depths would in this scenario be up to 6-7 km for production drilling. The only major deformation zone in the area stretches in a WNW direction from Kalmar and has potential for containing deep open fractures. The Boda-Örsjö area appears to host an extensive fracture network of multiple converging fracture zones. However, prediction of fracture occurrence at depths of several kilometres is highly speculative since no deep drill data has been produced in the area. Suggestions for further studies required in order to develop a deep geothermal project in the region are provided, with emphasis on locating favourable structural settings and bedrock stress conditions. Nevertheless, technical method developments regarding drilling and fluid injection are likely required for enabling deep geothermal energy production in the relatively cold depths of the exposed crystalline bedrock characterizing both the examined area in this report and the predominant parts of Scandinavia.