Glasgow mine workings scheme could lead to heating for millions of homes

The project has been funded by the Natural Environment Research Council (NERC) and the British Geological Survey (BGS) as part of the £31 million UK Geoenergy Observatories Project and is expected to continue for 15 years.

It is estimated that a quarter of all UK homes and businesses, some 9m buildings sit on former coalfields. The industry powered the British economy for more than a century but the last deep mine in Scotland, at Longannet, Fife, closed in 2002, while the last in the UK, in North Yorkshire, closed in 2015.

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So far, scientists have drilled four boreholes with the remaining eight partially drilled exploratory channels to be completed by autumn this year.

The research into Glasgow’s geology, its underground water systems and the potential for heat from the water in the city’s disused coal mines is expected to provide vital data that could help the UK and other countries access low-cost, low-carbon heating.

Measurements will be taken from the underground observatory boreholes such as temperature, water movement and water chemistry over the period.

Environmental baseline monitoring of near-surface chemistry, gases and waters will also be measured.

Data has been gathered since the first borehole was drilled in December 2018 and the research is open to be accessed by all including scientists, governments and regulatory bodies.

Researchers will observe the flooded mine workings beneath the east end of the city by monitoring the network of boreholes and seeing how warm water moves around the abandoned mine workings over time, monitoring changes in the chemistry and to the physical and microbiological properties of the environment just below the surface.

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The boreholes in Rutherglen are on the site of the Former Farme Colliery which closed in 1921.

Scientists will use the data extracted through the holes to discover how much the disused network of mine workings from Glasgow down to the Lanarkshire coalfields remains interconnected.

Alison Monaghan, geologist and science team lead for the Glasgow Observatory, said: “There were lots of mines in the area and one of the questions the project is trying to answer is if this colliery is still connected to lots of others still underground.

“We hope to find out the size of the resource when we drill them. The areas of coal fields were not continuous but are over tens of kilometers and we could potentially be getting a window into a big area or we might not be - until we drill we don’t know.”

The Coal Authority, which estimates there is enough geothermal energy in coal mines to heat 180 milllion homes, is preparing a map of potential mine water resources in Britain which could be utilised in the future of sustainable energy.

Ms Monaghan said: “Across the world there are already small schemes that use the technology of mine water geothermal and in the first couple of years of what we’re doing in Glasgow should have a big impact as to how more widely the technology could be used.

“Over the 15 year timescale there will be lots of different science questions about how long these resources can be used for and the thing you need to do to keep the scheme working over a long timescale.”

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Data has already been uploaded to the project’s website which is being used to look at the chemistry of the water and how much water can be taken out sustainably.

To generate the geothermal heating, water will be pumped from the mines through a heat exchanger and then pumped back underground.

The amount of water expected to be extracted from the mine workings could be up to anything from 5 to 10 litres a second up to 60 or 70 litres a second.

Ms Monaghan said: “When they were doing the mining they had to keep the mines dry for the people working down there so they had massive pumps at that time. It just depends, different coalfields have different water rates.”

Scientists will carry out tests to find out how much water can be pumped out and then measure the affect on the temperature, monitored by the boreholes. From there, modelling would be carried out to ascertain what the impact would be if that amount continued to be pumped out over time.

This research will enable the project to calculate how much heat the area could potentially produce.

But the project is not just about removing heat but also re-injecting and reusing it as well storing it underground when not in use - helping to meet climate change targets globally.

Ms Monaghan said: “Any spare heat can be stored in summer and extracted in the winter when it is most needed, using the underground as an inter-seasonal store.

“That’s another area that could help mitigate climate change. Storing renewable energy is a real challenge so that’s one of the things people might want to use the observatory for.”

Professor Zoe Shipton, Professor of Geological Engineering at the University of Strathclyde and Chair of the UK Geoenergy Observatories Science Advisory Group, said:”More and more of the solutions to decarbonising our energy supply will need to come from beneath our feet. Ensuring we take forward these solutions in a sustainable way means understanding more about how the system works. 

“The UK Geoenergy Observatories will build up a high resolution picture of the underground system, providing a breakthrough in our understanding. This hasn’t been done anywhere else in the world. What we learn in Glasgow will lead the way in understanding how to balance our need for resources, with keeping people safe and protecting our environment.”