A Review of the Performance of Minewater Heating and Cooling Systems

As the decarbonisation of heating and cooling becomes a matter of critical importance, it has been shown that flooded mines can provide a reliable source of low-carbon thermal energy production and storage when coupled with appropriate demand via an appropriate heat transfer technology. This paper summarises the potential resource represented by a long legacy of mining operations, the means heat can be extracted from (or rejected to) flooded mine workings, and then considers the risks and challenges faced by minewater geothermal energy (MWG) schemes in the planning, construction, and operational phases. A combination of site visits, interviews and literature reviews has informed concise, updated accounts for many of the minewater geothermal energy systems installed across the world, including accounts of hitherto unpublished systems. The paper has found that a number of previously reported MWG schemes are now non-operational. Key risks encountered by MWG schemes (which in some cases have led to decommissioning) include clogging of system components with mineral precipitates (e.g., ochre), uncertainty in targeting open mine voids and their hydraulic behaviour, uncertainty regarding longevity of access to minewater resource, and accumulated ongoing monitoring and maintenance burdens.