Can Abandoned Mines Heat our Future?
Charlotte Adams, Durham University
The UK faces an energy crisis, around half of the energy it consumes is used for heat and most of this is produced using natural gas. The UK has been a net importer of gas for over a decade, and we have limited gas storage meaning that at times of high demand we risk a supply shortage. There exists an opportunity to develop our deep mining heritage to once again provide a source of energy. Over the past century, 15 billion tons of coal were extracted from UK coalfields but output has reduced to virtually zero today. Our declining coal industry means that as deep mines were abandoned, water pumps were turned off and the worked areas flooded with water which now lies at temperatures of around 12 to 20°C.
Spread the previously mined coal over the entire UK land surface and there would be a layer of coal around 5 cm deep. The extracted coal has left void space underground, and allowing for subsidence, we estimate that there are around 2 billion cubic metres of water within flooded, abandoned coal mines. Using heat pumps, we can upgrade the temperature of this water to provide useful temperatures for space heating. The beauty of this concept is that because many villages, towns and cities were developed due to the coal deposits beneath them, there is good correlation between areas of heat demand and abandoned coalfields. It is estimated that the resource potential of the UK could provide heat for around 700 000 homes.
This potential aligns well with the UK Government’s 5th Carbon Budget and plans for the decarbonisation of heat that include one in twenty homes being connected to a district heat network by 2030. At current build and connection rates, this will be a challenging target to meet. The Coal Authority maintain the liability for the UK abandoned mines and currently pump water from several coalfields to protect aquifers and prevent emergence at unwanted locations. They estimate that the water pumped for operational reasons contains around 80MW of heat, which is currently unused. The use of abandoned mines as a source of heating and cooling has been proven at smaller scale in the UK and at district scale in the Netherlands, Germany and Canada. In its flooded mining infrastructure, the UK has a readily developed resource that could be used to provide heating and cooling but also has great potential for heat storage and offers one route to decarbonising future heat supply.
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14.30 Tea and coffee served in the lower library
15.45 Questions and answers
16.00 Lecture ends and guests depart