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Durham University

Research & business

The heat beneath our feet

(17 September 2019)

Old coal mines could provide us with a source of low-carbon heat for many years to come, according to geothermal energy expert Dr Charlotte Adams, who is the new President of the Geology section at the British Science Association.

Here, Charlotte, who is a member of our Durham Energy Institute, explains more about her research into how water stored in flooded abandoned mines could provide cleaner energy for homes and businesses.

Q. What is mine energy?

A. Mine energy is a type of geothermal energy - meaning energy which comes from the heat that the Earth’s core produces. This heat is a great potential energy source but we also need water to enable us to bring geothermal energy to the surface. This is where mines come in.

When mines are in use, there is a constant process of pumping water out so that miners can safely access the coal. However, when mines are closed and this pumping stops, the mines gradually fill up with water.

Geothermal energy naturally heats this water to around 12-20 degrees Celsius. This might not sound that warm but, by passing the water through a heat exchanger, the heat can be boosted to around 40 degrees Celsius; warm enough to heat homes and businesses.

Q. What are the potential benefits of mine energy?

A. In the UK around one third of all the energy we use is to produce heat. Mine energy would allow us to generate heat using much less fossil fuel than our traditional forms of heating, like gas-fired boilers, therefore helping to ‘decarbonise’ our heat production. 

The UK has over 23,000 former deep mines, meaning there is lots of potential for mine energy. We have calculated that floodwater could heat millions of homes as well as providing reserves to meet the UK’s heat demand for over a century.

Mine energy also offers the opportunity to generate more of our heat from resources right here in the UK, rather than relying on imported gas, giving us greater energy security.

Q. Are there any mine water energy projects already running?

A. There are around 20-30 mine energy projects globally, of various sizes. The earliest mine energy systems were set up in the USA in 1992 and Canada in 1994.

Recently a winery in Gateshead, UK, has developed the first commercial mine energy project in the UK to heat their warehouses.

Q. What are the next steps?

A. We are working hard to lobby the government to consider mine energy as part of the UK’s future energy mix.

We have also been raising awareness of the potential of mine energy, for example with former mining communities.

There is of course more work to be done. We are keen to develop and monitor some test projects to understand about the technology and how water and heat flows through abandoned mines in the long-term.

Find out more:

Read more about Dr Charlotte Adams and her research here

More about geothermal energy research at Durham University

Find out more about the Durham Energy Institute

More information about the British Science Academy 2019 section presidents

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