New research could help predict how much energy could be harnessed from the heat collecting in abandoned mines.
Researchers from McGill University in Montreal said using this kind of geothermal energy could benefit up to one million people in Canada and have even greater potential for more densely populated countries such as Britain.
By analysing the heat flow through mine tunnels flooded with water, the group has created a model that can be used to assess the thermal behaviour of a mine under different heat-extraction scenarios.
‘Abandoned mines demand costly perpetual monitoring and remediating,’ said lead researcher Seyed Ali Ghoreishi Madiseh. ‘Geothermal use of the mine will offset these costs and help the mining industry to become more sustainable.’
In a paper due to be published in the American Institute of Physics’ Journal of Renewable and Sustainable Energy, the researchers calculate that each kilometre of a typical deep underground mine could produce 150kW of heat.
As with other geothermal plants, hot mine water can be pumped to the surface, the heat extracted and the cool water returned to the ground. But for this to be sustainable, the heat must not be removed more quickly than it can be replenished by the surrounding rock.
The world’s first mine water power station was opened in Heerlen in the Netherlands in 2008 to show how this form of geothermal energy can be used to heat and cool buildings.
The British Geological Survey estimates that extracting around one per cent of the heat available in mines beneath Glasgow could contribute at least 40 per cent of the city’s heating demand every year.