Abandoned mineshafts could be used to heat Glasgow

Experts from Glasgow Caledonian University (GCU) believe that disused coal mines could help to solve the problem of fuel poverty within Scotland’s largest city. The researchers, whose work is being partly funded by ScottishPower Ltd, suspect that the warm water contained within Glasgow’s abandoned mineshafts can be used to heat roads, pavements and homes.

This might sound too good to be true, but Glasgow wouldn’t be the first city in the world to adopt such an approach. Hamburgers and Stockholmers already enjoy similar systems that take advantage of the geothermal energy beneath their feet. If the team – led by Project Director Dr Nick Hytiris, Senior Lecturer at GCU's School of Engineering and Built Environment – concludes that Glasgow is a suitable candidate for such a system, it has been calculated that the subterranean water supply could provide heating for approximately 40 per cent of the city’s population.

To find out more about the benefits that might result from this network of almost-forgotten mineshafts, I spoke to GCU’s Bjørn Aaen, a participating researcher and former technical advisor to Glasgow City Council. I began by asking how he and his colleagues plan to identify reservoirs with the potential to fuel this under-street heating system.

"We will begin by studying the maps that have already been developed by Glasgow City Council and the British Geological Survey (BGS)," Aaen replied. "These 3D models are really detailed representations of subterranean Glasgow, and they show that there are reservoirs of water stored within the city’s old mine workings. The trick will be to identify the best reservoirs to use. Utilising very shallow mine workings, for instance, could cause problems relating to instability. Having said that, any water that we draw from reservoirs will be pumped back again, so there should be very little overall change in volume.

"Even so, it might be more sensible to choose reservoirs that exist at a depth of about 50m or so," he continued. "At these levels, the temperature doesn’t tend to vary with the seasons. You don’t have to go very deep into the ground to find water with a temperature that remains stable all year round."

Of course, assuming that Aaen and his colleagues do find a sufficient number of reservoirs to make this project economically viable, it still remains for them to pump the warm water to the places in which it is needed. I asked how difficult it would be to integrate such a system within Glasgow’s already bustling underground infrastructure.

"To some extent, this depends on the distance that the water has to travel," Aaen explained. "In certain cases, it will be necessary to dig up streets in order to install new pipes and cables. I think that working out how to do this will prove to be the biggest challenge. However, a lot of our work is likely to be carried out in conjunction with new developments in which a centralised heat-pumping system will distribute water around houses and offices. For example, we are going to be working in the Clyde Gateway Regeneration area; the largest regeneration area in Scotland. As we will be starting from scratch, installing geothermal heating systems will cause very little disruption. Naturally, we will do our best to avoid digging anything up without good reason."

In the United Kingdom, a household is said to be in fuel poverty if – in addition to meeting the costs of utilities such as lighting, appliances, cooking and water heating – it spends more than 10 per cent of its income on maintaining a satisfactory heating regime.¹ During recent years, energy prices have risen at a faster rate than the average income in Glasgow, leading to higher levels of fuel poverty across the city. Indeed, according to the 2008 Scottish House Condition Survey, 25 per cent of Glaswegian households are ‘fuel poor’.²

In light of such statistics, I asked Aaen about the extent to which this initiative will provide heating for domestic purposes? How many people could benefit from Glasgow’s geothermal energy resource?

"It has been calculated that during a 100-year period, up to 40 per cent of Glasgow’s heating needs could be met by this energy resource," he replied. "It has the potential to make fuel costs more affordable for huge numbers of people. Moreover, there is existing evidence to this effect. The residents of Glenalmond Street have had this system installed for over a decade now. Whilst I am only talking about 17 houses – it is quite a small setup – the residents have reported that their heating bills have dropped to approximately £150 per year. Heating homes in this way is much cheaper than using gas or electricity."

Finally, I asked Aaen whether other UK cities are likely to follow suit if he and his colleagues find Glasgow to be a suitable host for this expansive geothermal heating infrastructure. As he explained, locations across the home nations could take advantage of their mining heritages.

"There are numerous towns and cities that exist above old mine workings similar to those that can be found beneath Glasgow," Aaen concluded. "Places across Central Scotland, England and Wales could certainly benefit from the same type of technology. After all, the remnants of mining past are spread widely across the UK and beyond."


¹ 'Topic guide to: Fuel Poverty', UK National Statistics
² 'Fuel poverty', Understanding Glasgow: The Glasgow Indicators Project