Geology and Landscape, Scotland Programme Commissioned Report Cr/12/131
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Energy The Scottish Government August 2013 Study into the Potential for Deep Geothermal Energy in Scotland Scottish Government Project Number: AEC/001/11 Volume 2 of 2 BRITISH GEOLOGICAL SURVEY GEOLOGY AND LANDSCAPE, SCOTLAND PROGRAMME COMMISSIONED REPORT CR/12/131 Deep geothermal energy The National Grid and other Ordnance Survey data © Crown Copyright and potential in Scotland database rights 2013. Ordnance Survey Licence No. 100021290. Keywords M R Gillespie, E J Crane and H F Barron Geothermal energy, Scotland, minewater, Hot Sedimentary Aquifer, HSA, Hot Dry Rock, HDR, BGS, AECOM, Scottish Government. Front cover 3D model of coal seams, mine shafts and mine roadways under the east end of Glasgow. Viewed in Virtalis/BGS GeoVisionary software. Bibliographical reference GILLESPIE, M R, CRANE, E J and BARRON, H F. 2013. Deep geothermal energy potential in Scotland. British Geological Survey Commissioned Report, CR/12/131. 129pp. Copyright in materials derived from the British Geological Survey‘s work is owned by the Natural Environment Research Council (NERC) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining permission. Contact the BGS Intellectual Property Rights Section, British Geological Survey, Keyworth, e-mail [email protected]. You may quote extracts of a reasonable length without prior permission, provided a full acknowledgement is given of the source of the extract. Maps and diagrams in this book use topography based on Ordnance Survey mapping. © NERC 2013. 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Tel 020 7942 5344/45 email [email protected] Columbus House, Greenmeadow Springs, Tongwynlais, Cardiff CF15 7NE Tel 029 2052 1962 Fax 029 2052 1963 Maclean Building, Crowmarsh Gifford, Wallingford OX10 8BB Tel 01491 838800 Fax 01491 692345 Geological Survey of Northern Ireland, Colby House, Stranmillis Court, Belfast BT9 5BF Tel 028 9038 8462 Fax 028 9038 8461 www.bgs.ac.uk/gsni/ Parent Body Natural Environment Research Council, Polaris House, North Star Avenue, Swindon SN2 1EU Tel 01793 411500 Fax 01793 411501 www.nerc.ac.uk Website www.bgs.ac.uk Shop online at www.geologyshop.com Foreword This report contains the BGS contribution to a collaborative project between AECOM and BGS to produce a qualitative assessment of deep geothermal energy potential in Scotland for the Scottish Government Study (Scottish Government Contract Ref. CR/2011/07) into the Potential for Deep Geothermal Energy in Scotland. BGS was asked to provide the Stage One deliverable ―Identifying and assessing geothermal energy potential‖, comprising an assessment of areas in Scotland most likely to hold deep geothermal resources based on existing geological and geothermal data sets. AECOM undertook the Stage 2 deliverable ―Development of Key Policy Options‖ in which policy options and key actions are identified that the Scottish Government can potentially implement to encourage commercial exploitation of the available geothermal resource. Acknowledgements In addition to the authors of this report, several other BGS staff have contributed to this study, namely Jon Busby, Diarmad Campbell, Adrian Walker and Bill McLean. 1 Contents Foreword ........................................................................................................................ 1 Acknowledgements ....................................................................................................... 1 Contents ......................................................................................................................... 2 Executive summary ....................................................................................................... 7 Introduction ............................................................................................................... 7 The heat resource in Scotland .................................................................................. 7 Geological settings for exploiting geothermal energy ................................................ 8 1 Introduction ........................................................................................................... 15 2 Background to geothermal energy ...................................................................... 17 2.1 Sources of heat, heat measurement and factors affecting heat transfer ......... 17 2.2 Classification and exploitation of geothermal resources ................................. 20 3 The geological context ......................................................................................... 24 3.1 Some terminology and concepts ..................................................................... 24 3.2 Bedrock geology of Scotland .......................................................................... 26 4 Geothermal data for Scotland .............................................................................. 31 4.1 Heat flow data ................................................................................................. 31 4.2 Borehole temperature data ............................................................................. 36 5 Key conclusions and recommendations arising from Part 1 ............................ 46 5.1 Conclusions .................................................................................................... 46 5.2 Recommendations .......................................................................................... 47 6 Abandoned mine workings .................................................................................. 50 6.1 Introduction ..................................................................................................... 50 6.2 Previous studies and existing installations ...................................................... 53 6.3 Geology and mining history ............................................................................ 53 6.4 Hydrogeology of abandoned mines ................................................................ 58 6.5 Data and information availability for Scotland ................................................. 60 6.6 Methodology ................................................................................................... 68 6.7 Calculations/Results ....................................................................................... 69 6.8 Future possibilities .......................................................................................... 73 6.9 Conclusions .................................................................................................... 73 6.10 Recommendations .......................................................................................... 73 7 Hot sedimentary aquifers ..................................................................................... 74 7.1 Introduction ..................................................................................................... 74 7.2 Previous investigation of geothermal potential in Scottish aquifers ................ 74 7.3 HSA potential based on bedrock aquifer productivity ..................................... 75 2 7.4 Onshore margins of offshore basins ............................................................... 81 7.5 HSA prospects beneath low thermal conductivity rocks ................................. 81 7.6 Conclusions .................................................................................................... 82 7.7 Recommendations .......................................................................................... 82 8 Hot Dry Rocks (Enhanced Geothermal Systems) .............................................. 83 8.1 Introduction ..................................................................................................... 83 8.2 High Heat Production (HHP) granite ............................................................... 84 8.3 Low thermal conductivity rocks in areas of elevated heat flow...................... 104 8.4 Geothermal potential in low permeability sedimentary rocks ........................ 106 8.5 Conclusions .................................................................................................