Ilona Amos: Do ‘dirty’ old coal mines hold the key to clean geothermal energy?

Warm water contained in disused mines shafts could offer a low-cost and sustainable source of green geothermal energy. Picture: Ian Rutherford
Warm water contained in disused mines shafts could offer a low-cost and sustainable source of green geothermal energy. Picture: Ian Rutherford
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Some of Scotland’s most densely populated communities are sitting on what could, quite literally, be a hotbed of limitless clean energy.

Though our coal industry is pretty much dead and buried, the landscape today still bears the legacy of a long history of mining across the central belt. And it’s this network of disused shafts that experts believe could hold the key to what is a potentially massive – and so far virtually untapped – resource of green power derived from geothermal energy.

Geothermal has advantages over other renewable energy sources, which are often criticised for their intermittent nature. It is able to provide baseline power since it doesn’t rely on the sun shining, the wind blowing or the tide going in and out.

Two small-scale experiments using ground source heat pumps to tap warm water collected in defunct mines in Glasgow’s Shettleston and Lumphinnans in Fife have already proved successful, but those who know about these things say it’s time to think bigger, much bigger.

The British Geological Survey (BGS) and the Natural Environment Research Council (NERC), the UK’s main funding body for earth sciences, have unveiled plans to investigate the true scope of recovering heat from water trapped deep underground in abandoned mines in a pioneering new project that will be based either in the east end of Glasgow or in Rutherglen, South Lanarkshire.

The proposed Glasgow Geothermal Energy Research Field Site is one of two such schemes being put forward as part of the £31 million UK Geoenergy Observatories Project. The other one will be in England.

Extensive records from mining, oil and gas exploration and civil engineering works are already held in by BGS in a national archive, but it’s hoped findings from the new project will help experts properly understand the impact of exploiting geothermal energy in this way and to establish whether it can be a viable, cost-effective and sustainable addition to the renewables sector.

One of the proposals is for a site in the Clyde Gateway area. It involves the creation of a number of boreholes of depths up to 170m that will allow scientists to explore the area’s geology and underground water systems.

Water temperature, movement and chemistry will be tested, with data continuing to be monitored and assessed over the coming 15 to 25 years.

Studies will also be carried out to ascertain whether gathering geothermal energy is likely to cause earthquakes, as has happened with fracking, or lead to water pollution,

At the same time researchers hope to discover how extensively the mine network is linked and whether tapping water at one site might affect supplies contained in a shaft elsewhere.

If the project gains all the necessary planning consents, drilling work is expected to begin at the chosen site next year.

Diarmaid Campbell, chief geologist for BGS in Scotland, hopes the £9 million project will help geothermal energy become more mainstream and open up new opportunities. So far the first three phases of the project have been sketched out, but he says there is plenty of scope for further collaboration.

Local residents, businesses and anyone who wants to discover more about geothermal energy can find out about the proposals in more detail at a special event being held in Glasgow on 5 September, where experts will be on hand to answer questions.