Geothermal energy prospecting in radiothermal granites in the Cairngorms, Scotland, using an integrated geological, geophysical and petrophysical appr

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Geothermal energy is one of the few renewable energy sources that can supply a constant and reliable source of low-carbon heat, and in some cases electricity. In the UK, radiothermal granites offer one of the best potential targets for medium/medium-high enthalpy (100-200 degrees C fluid temperature) geothermal energy resources, within conventional drilling depths (2-5 km). Scotland hosts the highest heat producing granites in the UK, primarily situated in the Cairngorms. Until now, one of the main reasons why there has been a lack of investment in developing projects within the Scottish granites is that it is not known to what extent permeable (fractured and/or altered) zones exist at depth. Detecting these features in the subsurface is non-trivial, given that they are not easily observable using e.g. seismic surveying methods. However, using electromagnetic deep-sounding techniques like the magnetotelluric (MT) method offers the potential to image such features at depth where the electrical resistivity of the host rock (granite) will be much higher than in altered, porous and/or fractured zones, where geothermal fluids are likely to exist.Through our collaborations with the British Geological Survey and TownRock Energy, the successful candidate will lead groundbreaking multidisciplinary research to better understand the geothermal energy potential of the granites in the NE of Scotland, collecting and integrating new data from a combination of field, lab and subsurface imaging methods. Specifically, the PhD project will involve carrying out a series of field excursions to areas where there are radiothermal granites in NE Scotland (e.g. the Cairngorms) to map surface features (e.g. fracture, faults, alteration zones), carry out an MT survey and collect samples to measure the petrophysical properties of potential reservoir rocks using laboratory methods. The integration of these different data sets will directly influence the next stage of geothermal energy exploration in Scotland, but they will also be important in understanding other similar systems worldwide.