Flooded and forgotten: how Europe’s disused coal mines could help heat our homes

Abandoned coal mines could provide a surprisingly powerful source of carbon-free energy in Europe.

Around a quarter of homes in the UK sit above the country’s vast maze of former mining tunnels, according to the British Coal Authority. After decades of disuse, they gradually flooded.

Heated by the earth, this liquid provides an answer to our renewable energy needs. It can be pumped and used to power homes and buildings in the area.

With around 2 billion cubic meters of hot water – more than a quarter of the volume of Loch Ness – geologists believe Britain’s mine shafts contain one of the biggest underutilized sources of clean energy.

“Recovering heat from mine water below ground in abandoned coal mines offers an exciting opportunity to generate a safe, low-carbon heat supply for the benefit of people living or working in buildings on coalfields,” says Gareth Farr, Head of Heat and Product Innovation at the Coal Authority.

“With several million people living in abandoned coalfields in Britain, the heat potential of mine water could be significant.”

Tapping into the heat of water in the mines has the added benefit of boosting the economies of some of the communities hardest hit by the deep coal mine closures in the 1980s. So how does it work? exactly and where does it take off?

How can flooded mines help heat homes?

The water in the mine gets warmer as it goes deeper, because this interactive map shows former UK Coal Authority coal mines. Temperatures generally range from 10-20°C but can reach up to 45°C at depths of 1km – as at the Yorkshire site.

Left to mix with underground rock, the water often contains toxic compounds. But as a heat source, it’s a valuable resource that can be tapped by drilling boreholes that bring it to the surface.

The water is then directed through heat pumps and extractors which compress the liquid, bringing it to a much higher temperature before distributing it to the heating networks.

Once its heat has been absorbed in the surrounding buildings, the water can be returned to the mining system where it will be reheated again.

The heating of the mine water also has the advantage of operating all year round. Temperatures are not affected by the seasons and the water can be used to cool homes as well as heat them.

Which UK cities are tapping into the energy source?

The UK is in an exploratory phase with its mine water heating systems. the UK Geoenergy Observatory (UKGEOS) based in Glasgow and run by the British Geological Society, is one of the main research stations.

After the busy mines in the Scottish town and neighboring town of Rutherglen closed, natural flooding filled them with water at around 12C. Last summer, a dozen boreholes drilled on the site and equipped with hundreds of sensors provided a more accurate picture of the network of flooded tunnels. They revealed how fast the water flows between the mines, how hot it is, how quickly it replenishes and heats up.

“The data from these 12 boreholes in Glasgow will help scientists around the world better understand underground and geothermal energy,” said UKGEOS’ Alan MacDonald.

The Glasgow Observatory and another project in Cheshire are part of a £31m (€37m) investment from the Department for Business, Energy and Industrial Strategy (BEIS). Funding for this research reflects the government’s growing interest in this amazing form of geothermal energy.

Once at the heart of the Industrial Revolution, North East England is now innovating on the practical side of this alternative energy source. Gateshead Council is set to commission its 3MW mine water heating network later this year, says Farr, the first of its kind in the UK to supply multiple homes and businesses in a town.

“This is just one example of how we are transforming our mining heritage into a geoenergy asset for a greener and more sustainable future,” adds the heating expert.

Tyneside is also transforming its old Hebburn mine, abandoned since the 1930s, into a geothermal generator. The £7.7m (€9.2m) investment – funded half by South Tyneside Council, half by the European Regional Development Fund – is set to power a number of municipal buildings by summer 2023.

Even better, its water-source heat pump will be powered primarily by solar panels installed on nearby rooftops.

European geothermal pioneers

By drawing on its history to create new geoenergy assets, the UK is following in the footsteps of other European countries.

The world’s first mine water power station opened in the Dutch town of Heerlen in 2008. It is now connected to around 500 homes and commercial facilities – reduce the region’s carbon emissions related to heating by almost two-thirds.

A similar project is underway in the rugged region of Asturias in northern Spain, where flooded coal pits are heating (and cooling) a hospital, university and many other buildings.

“Geothermal energy has given a second life to our coal mines,” said Asturias energy director María Belarmina Díaz Aguado. the bbc.

Countries reallocating their underground reserves are also looking further north, towards geothermal pioneer Iceland.

But although the first mine-water power plant is on European soil, the technology was harnessed nearly two decades earlier in Springhill, Nova Scotia.

Synonymous with mining disasters, the Canadian community began using heat from its idle coal mines in 1989. A packaging company in town now has a 100% renewable, year-round system.

Mary I. Bruner