Mine Water Geothermal Resource Atlas for Scotland

A Web Mapping Feature layer identifying optimal locations across Scotland for mine water geothermal development. Mine water geothermal energy describes the low-carbon practice of using water held in abandoned flooded mines to heat or cool surface thermal demands. The low temperatures (as low as 10°C) require heat pump technology to upgrade thermal energy to usable temperatures for heating homes or industrial applications. The intention of the mine water geothermal resource atlas is to highlight optimal areas to exploit MWG energy in Scotland. If the scale of Scotland’s mine water thermal resource, estimated at 12 GW, becomes better communicated we envisage that this atlas will prove influential for increasing the rate and success of MWG deployment. Ideally, the provision of feasible MWG sites will influence stakeholder decisions i.e., where to invest and develop land to make the best use of the low-carbon resource, resulting in MWG potential included as part of a standard appraisal for a residential or industrial development plan. Whilst it is acknowledged that focused expert input would be required to integrate surface heat demand and subsurface resources in detail, the atlas provides non-experts and decision makers with a first-pass high-level summary of the potential MWG resource located within their area of interest. The four criteria for site selection are summarised below: 1. There are more than one (overlapping) mined seams. 2. The mined seams are deeper than 30 m to minimise subsidence risk. 3. The mine water head (i.e., mine “water table”) is not excessively deep (< 60 m below ground level) to avoid excessive pumping costs. 4. The mined seams are shallower than 250 m below ground level to minimise drilling costs. As a result, this atlas has identified a total of 370.3 km2 across 19 local authority areas which are most suitable for MWG development. Symbology: The calculated depths for mine water head (Criterion 3) are mapped in 10 m increments with shallower values (0 m – 20 m BGL) shown in shades of pink and deeper values (20 m - 60 m BGL) shown in shades of blue. Where mine water head is shallow (0 m - 20 m BGL) there may be some risk that reinjection may cause mine water heads to approach the surface (depending on the transmissivity of the workings). “Open loop with discharge” may be more feasible for areas with very shallow mine water (0 m - 20 m BGL), but may require additional permitting (discharge consents) and available land for treatment depending on water chemistry. Areas shaded blue (20 m - 60 m BGL) correlate with deeper mine water heads which are most suited to the ‘open-loop with reinjection’ configuration. Both configurations are presented in Walls et al. (2022) - https://doi.org/10.3390/en14196215. Depths greater than 60 m BGL are not included since they indicate situations which would face excessive pumping costs. Contains data from © The Coal Authority. All rights reserved.