Engineers from the University of Oviedo in Spain have published research which shows that mine shafts on the point of being closed down could be used to provide significant amounts of geothermal energy.

The engineers have developed a method which makes it possible to estimate the amount of heat that a tunnel could potentially provide.

According to Rafael Rodríguez, from the Oviedo Higher Technical School of Mining Engineering, "one way of making use of low-intensity geothermal energy is to convert mine shafts into geothermal boilers, which could provide heating and hot water for people living nearby".

The study, published in the Renewable Energy Journal, gave as an example the geothermal energy potential of a two-kilometre-long mine shaft, in which the temperature of the rocks 500 metres below the surface is around 30º C. It found that water could be forced in through tubes at 7º C and return at 12º C, a big enough heat gain to be of benefit to towns located above the mines.