The Anonymous Widower

Can Abandoned Mines Heat Our Future?

The title of this post, is same as that of the title of a public lecture I attended at The Geological Society this afternoon.

This page on the Geological Society web site, gives a summary of the lecture and details of the speaker; Charlotte Adams of Durham University.

The Concept

The basic concept is simple.

  • Abandoned coal mines had their pumps turned off when they are closed and the worked areas have flooded with water, that is now at temperatures of around 12 to 20°C.
  • As fifteen billion tonnes of coal have been extracted from UK coalfields, that is a lot of space to flood. An estimate of around two billion cubic metres is given.
  • This means that the water holds somewhere between 27.9 and 46.5 GWH of energy in the form of heat.
  • Heat pumps would be used to upgrade the temperature of this water, to provide hot water at useful temperatures for space heating.

For those unfamiliar with the concept of a heat pump, Wikipedia gives a good explanation, of which this is the first paragraph.

A heat pump is a device that transfers heat energy from a source of heat to what is called a heat sink. Heat pumps move thermal energy in the opposite direction of spontaneous heat transfer, by absorbing heat from a cold space and releasing it to a warmer one. A heat pump uses a small amount of external power to accomplish the work of transferring energy from the heat source to the heat sink.

In connection with this project, the heat source is the warm water in the mines and the heat sink is the water that is circulated to heat the buildings.

Wikipedia goes on to say this.

In heating mode, heat pumps are three to four times more effective at heating than simple electrical resistance heaters using the same amount of electricity. However, the typical cost of installing a heat pump is also higher than that of a resistance heater.

Wikipedia also has a section, which descries the use of heat pumps in district heating.

It should also be noted, that as with lots of technology, heat pumps are much improved, from the one I installed in a swimming pool in the 1980s.

Gas Is Replaced By Renewable Energy

The electricity to drive the heat pumps could be derived from renewable sources such as hydroelectric, solar, wave or wind.

Effectively, the system is using intermittent sources of electricity to create a constant source of heat suitable for space heating.

Would The Mines Run Out Of Heat Or Water?

As I understand it, the water in the mine will continue to be heated by the heat in the mines. The father of a friend, who came with me to the lecture was a coal miner and my friend confirmed it was hot in a coal mine.

The water will of course continue to flood the mine and the water pumped to the surface will probably be returned.

So the system will continue to supply heat for space heating.

How Long Will The System Supply Heat?

The system has the following characteristics.

  • It is electro-mechanical.
  • It is powered by electricity.
  • Water is the heat transfer medium.
  • Additives like anti-freeze will probably be applied to the water used for heat transfer.

There is no reason the system can’t be designed, so that it supplies heat for many years with regular maintenance and updating.

How Does The System Compare To Bunhill 2 Energy Centre?

In Bunhill 2 Energy Centre, I described Islington’s Bunhill 2 Energy Centre which uses heat generated in the Northern Line of the London Underground to provide district heating.

I am fairly sure that a lot of similar technology will be used in both applications.

This page on Wikipedia is entitled London Underground Cooling.

There is a section, which is entitled Source Of The Heat, where this is said.

The heat in the tunnels is largely generated by the trains, with a small amount coming from station equipment and passengers. Around 79% is absorbed by the tunnels walls, 10% is removed by ventilation and the other 11% remains in the tunnels.

Temperatures on the Underground have slowly increased as the clay around the tunnels has warmed up; in the early days of the Underground it was advertised as a place to keep cool on hot days. However, over time the temperature has slowly risen as the heat sink formed by the clay has filled up. When the tunnels were built the clay temperature was around 14ºC; this has now risen to 19–26ºC and air temperatures in the tunnels now reach as high as 30ºC.

So one big difference is that the Underground is warmer than the mine and this should make it a better heat source.

I feel that engineers on both projects will benefit from the ideas and experience of the others.

Would Infrastructure Funds Back This Technology?

In the UK, there are several infrastructure funds set up by companies like Aberdeen Standard, Aviva, Gresham House and L & G.

In World’s Largest Wind Farm Attracts Huge Backing From Insurance Giant, I explained why Aviva had invested nearly a billion pounds in wind farms to support pensioners and holders of their insurance policies.

Comparing the risk of using abandoned mines to heat buildings and that of offshore wind turbines generating electricity, my engineering knowledge would assign a greater risk to the turbines, providing both were built to the highest possible standards.

It’s just the onshore and offshore locations and the vagaries of the weather!

I think it is true to say, that infrastructure funds will back anything, where there is an acceptable long-term income to be made, commensurate with the costs and risk involved.

But then Government or any public or private company or organisation should not pay over the odds for the energy delivered.

Conclusion

Charlotte Adams in her lecture, asked if abandoned mines can heat our future.

The answer could well be yes, but there are other sources of heat like the London Underground, that can also be used.

 

 

 

 

December 7, 2018 - Posted by | Transport, World | , , , , , , ,

4 Comments »

  1. One of my fathers best friends was a geologist who had worked in coal mining all his life.
    He said that the lack of preservation of documentation of coal mines and the lack of preparation for their closure might be something that we would live to regret.
    I hope that we will have enough information to allow us to use the mines as energy stores as so fascinatingly explained here- as safe cheap battery alternatives- without being hampered by bad documentation. If this is a problem then we need some rapid ethnographic work to capture mine workers knowledge of workings to this end!

    Comment by David Collier | December 7, 2018 | Reply

    • Your father’s friend could well be right. In the rail industry, it can be a problem with Victorian structures to get reasonable documentation for electrification, bridge and station projects. The electrification project around Bolton is rumoured to have been delayed by the discovery of old mine workings.

      But at least in a flooded coal mine, I suspect there are technologies like underwater drones, that can have a close look. It would be like a large scale endoscopy!

      There is a project underway at Spennymoor to research the problems.

      https://www.dur.ac.uk/dei/news/?itemno=29972

      Incidentally, at Spennymoor Mining Museum, they seem to have a lot of documentation.

      It should also be remembered that France, Germany, Poland, the United States and other countries have large numbers of abandoned coal mines and will probably be thinking of harvesting the heat.

      I also think strongly, that the game changer could be the Bunhill 2 Energy Centre, as the depths involved are lower, the temperature is higher and there is a wide existing shaft with good access.

      But what works in Islington will work anywhere in the world, although sizes will be larger.

      Comment by AnonW | December 7, 2018 | Reply

  2. […] projects, like those I discussed in Can Abandoned Mines Heat Our Future?, come on stream to provide heat, the role of gas in providing heating in housing and other […]

    Pingback by Funding Nemo: £600m Power Cable Connects UK And Belgium « The Anonymous Widower | December 7, 2018 | Reply

  3. […] Charlotte Adams mentioned in the article is the academic, who did the presentation I saw yesterday and talked about in Can Abandoned Mines Heat Our Future?. […]

    Pingback by Exciting Renewable Energy Project for Spennymoor « The Anonymous Widower | December 7, 2018 | Reply


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