Could England’s Disused Mines Be A Potential Source of Renewable Energy?

In the heydays of coal mines, few could have known the impact that the burning of fossil fuels would have on the planet.

Public officials are now hoping that disused mines that once produced millions of tonnes of fossil fuels could be used as a potential source of renewable energy across the country.

Mines that have remained unused for significant periods naturally become flooded with water, which will then become heated by geothermal energy, a form of renewable energy generated from the earth.

There has already been a precedent set by the success in Gateshead of the council-owned Gateshead Energy Company to use warm water from the extensive network of old mine workings 150 metres below the town to supply heat and hot water. 

The Gateshead Energy Company powers its centralised heat pump with a solar farm and estimates to be saving about 1,800 tonnes of CO2 a year. 

Ordnance Survey has published a report that suggests six million homes in the UK could be powered by mine water from disused coal mines. This would equate to two trillion litres of heated water stored underground which the Ordnance Survey’s study claims would make unused mine water one of the UK’s most underutilised clean energy sources.

John Kimmance, Managing Director of National Mapping Services at Ordnance, stated: 

"For every unit of electricity used, it [geothermal energy] can generate two to four times that in heat.
"It's a very efficient and therefore carbon-friendly way of heating. Some of these mines fuelled and powered the country over hundreds of years. It's a nice thought they could continue to do that in the future."

The study reveals that a quarter of UK homes currently sit on flooded coal mines that have been heated by geothermal energy underground. Using boreholes to dig deep underground the warm water can be brought to the surface to be used in heat pumps to provide heating for homes. The water can be extracted all year round without temperature fluctuations providing a consistent stream of energy.

Many authorities are now seeing the potential these once thriving disused coal mines present and are launching schemes to look at the viability of tapping into one of the UK’s most underutilised renewable energy sources. 

Dan Norris the mayor of the West of England has pledged funding to investigate the possible use of old, flooded coal mines as a source of clean thermal energy. 

Nearly a quarter of the region’s homes sit above inactive, flooded coal mines that could potentially be used to heat them. There are more than 100 of these coal mines in and around the Somerset Coalfield and South Gloucestershire areas in the West of England where coal was mined from the 15th century right up to 1973 when the last pit was closed.

At the end of January, the mayor Dan Norris announced his plans to launch a major £1.6m Heat from Mines study, backed by the UK’s Coal Authority and cultural government body Historic England, to look into whether disused mines in the region could be repurposed as a clean energy source to heat homes. The proposals put forward suggest that by using heat pumps, the water in these flooded mines which has been naturally warmed by the earth could be used to heat homes. 

The West of England Combined Authority (WECA), composed of the local councils of Bristol, South Gloucestershire, Bath, and Northeast Somerset is behind this trial and hopes the mine water can heat more than 100,000 homes In the West as well as other buildings such as hospitals, schools, and offices could be heated via regional heat networks. 

The plan to harness energy from the mines has been welcomed by locals including former miners who like the idea that the mines will be repurposed. The mines were a crucial part of the fabric of life in Radstock in days gone by with many miners left devastated when the pits shut in 1973 changing their way of life forever. 

Mayor Dan Norris said:

“I love the idea that coal mines could be repurposed to provide the clean energy of the future - it’s coming full circle. The synergy is fantastic that mines that contributed to COâ‚‚ emissions could now hold the key to clean, green energy. Generating homegrown energy also gives us the chance of cheaper bills, new high-paid jobs, and energy security from tyrants like Putin.
“Heat from mines has national, and possibly global, implications too. With many millions of people living above former coalfields right across the country, the potential for mine water heat could be huge… The climate crisis is the biggest challenge we face as a region, as a nation, and world. This is a real opportunity to explore an innovative way to heat our homes.”

The Heat From Mines study will map the mine areas that have the biggest potential heat resource leading to detailed ground investigation works. The new study builds on a similar investigative project announced in March 2023, as part of a larger £60m investment in green technology from the West of England Combined Authority, the region’s local council.

When the coal mines were up and running, they were pumped dry so miners could access the coal. But once the mines were closed the pumps were switched off and the mines flooded again. The water is heated by geothermal energy, the heat from the earth’s core, and in some places can reach temperatures of about 20C.

Dan Mallin Martin, a hydrogeologist with the Coal Authority, the public body responsible for managing the effects of past coal mining explains that the naturally heated water can be brought up through shafts or boreholes and passed through a heat exchanger to extract the heat from the water. 

Dan Mallin Martin said:

“Typically, we can take out around five to 8C, which doesn’t sound like a lot, but if you pass that to a heat pump, which is effectively a fridge in reverse, it boosts the temperature to something we can use, something like 60 or 70 degrees centigrade that can go into people’s homes, people’s businesses, into hospitals, heat networks, many different end users. That’s a great way to make use of that and they can be really efficient. And really low carbon.”

As the mine water is put back into the flooded mines and recycled the process has no net water consumption which means that it doesn’t take out more than it uses.

Gareth Farr, head of heat at the Coal Authority, said: 

“The Coal Authority is committed to facilitating mine water heat networks across Great Britain. We hope that the industrial heritage of coal mining in the West of England will also be able to support mine water heat networks in the future.”

Alex Davies-Jones MP, who heads up the All-Party Parliamentary Group on Coalfield Communities, said: 

"As an MP for a coalfield constituency, as well as being the daughter and granddaughter of miners, I'm delighted by the prospect of former coal mines once again being used to generate power and create jobs."
"Just as coal mining was integral to Britain's industrial revolution, with the right policies and investment, coalfield communities have the potential to be at the forefront of a 21st-century technological revolution.
"It is great to see the West of England Mayoral Combined Authority, led by Mayor Dan Norris, along with many other parts of the country, taking steps to turn this potential into reality."

This form of energy is being tested in the West of England to assess its suitability for heating homes following the report which suggested that six million homes could be heated using this renewable energy. 
Other similar projects have been launched, although not on this scale, such as in Cornwall where a borehole dug 5275 metres deep is being used to heat 3,800 homes. 

Undoubtedly, the transition to heat pumps as an energy source is extremely important as it constitutes one of our options for decarbonising our heating requirements across the whole of the UK.
Mallin Martin said:

“With heat pumps, ground source options, and mine water, we can feed into that decarbonisation, especially if we couple it with green electricity like solar panels and wind.
“There’s a real green incentive to make the most of this and it certainly supports the levelling up agenda in the communities on the coalfield by delivering secure, local, low-carbon heat,”

It is vital that we investigate ways of making the cost of energy cheaper as it affects not just the poorest in society but everybody and businesses.

Using the water from disused mines has the potential to become not only a cost-effective way of producing energy but also an environmentally important way of helping to cool down our planet. 

Charlotte Adams, the Coal Authority's principal manager for mine energy said:

“Mine water is one of our best options to help with the decarbonisation of heating. The resource is readily available all year round at a steady temperature, and there is an abundance to be accessed.
"It'll be cheaper than gas, too, by around 10%."

The climate crisis is the biggest challenge we face as a nation and the disused mines present a real opportunity to explore an innovative way to heat our homes and reach net zero targets.