Carrak Consulting Ltd. specialises in the assessment of land affected by former mineral extraction and wastes, as well as the re-purposing and regeneration of abandoned mine sites across Cornwall. It is also a member of the Southwest Geothermal Alliance (SGA), which is actively involved in the development and promotion of the geothermal energy resources beneath Cornwall.
Nature of intervention
The Coal Authority is developing heat resources from within former UK coal mines, however little development has occurred in Cornwall as further research is required into the viability of old, flooded metal mines to provide heating for SW England. Consequently, Carrak seeks to characterise the geochemical properties of water in flooded mine shafts to increase the knowledge base and de-risk the permitting process, to encourage commercial investment in the SGA and Carrak, as well as develop future heat recovery schemes.
Environmental permitting is a commercial risk to a potential mine water heat scheme because it can be complex and time-consuming to determine and costly to comply with. Increasing the data available on the composition of mine water at potential abstraction and reinjection locations, and at varying depths, reduces risk and cost while potentially supporting the transition to Net Zero. Common components of concern are suspended solids, pH, and certain dissolved metals because these may need treatment prior to reinjection if the receiving water has a different composition.
Value of any grant support
This Innovation Voucher project was awarded through DDC with a total value of £3,865.
How the DDC connection occurred
Mine shaft water is difficult to access and sample at discrete depths, but this has been made possible as Deep Digital Cornwall (DDC) is working with other SGA partners to survey shafts and help plug heat flow knowledge gaps as part of DDC’s Shaft Surveying Work Package.
What the business assist/grant has achieved
Temperature and geochemical sampling surveys are being conducted by European Geophysical Surveys (EGS) in strategic, deep shafts where there is either existing commercial interest or future potential for a mine water heating scheme. This provided an opportunity to sample and characterise the geochemical and physical properties of the water in tandem from both shafts and adits from mines around Camborne, Chacewater and the Tin Coast (Penwith).
Plans for the future
The results will be made available through the DDC data hub to interested parties, including the Environment Agency, and will enable comparisons between potential abstraction and reinjection water quality alongside relevant Environmental Quality Standards. The data also contain information on dissolved and total concentrations of certain light and heavy metals, which may provide insight on mineralisation.
