30 May 2023

Abandoned coal mines: the gold mines of geothermal energy

In the U.S., nearly $500 million from the Inflation and Infrastructure Reduction Act would go to clean energy projects in former coal mines.

When a coal mine ceases to operate, it usually fills with water. At a certain depth, this water is heated by the heat of the Earth’s interior. By drilling boreholes, this heat can be extracted from the mines and transferred to buildings and homes through heat exchangers and heat pumps.

A good example is to be found in Great Britain where, at the end of March, the first mine water heating system was commissioned and will serve more than 1,200 homes. According to Gareth Farr (Coal Authority of Mansfield, England), every mining project will have its own challenges, but, even if there is investment in drilling or laying pipes:

Most, if not all, of these systems, can operate at a similar or lower cost than the traditional fossil fuel systems we use today”

Geothermal energy from coal mines can not only be used for heating but also for cooling, allowing for many more opportunities. Data centers, for example, are some of the biggest carbon emitters, consuming huge amounts of energy and thousands of liters of water for cooling. These highly polluting players could benefit greatly from this renewable and efficient cooling system. Another possibility is being explored by Scottish researchers: pumping hot air from data centers into coal mines so that it can be recovered from the water to heat other buildings.

Ohio alone has more than 4,000 abandoned mines, and there are coal fields in at least 20 other states in the United States. The fact that coal is a controversial resource means that investors have not been looking at these regions, which turns out to be a mistake. Coal mines are a great opportunity for geothermal energy, clean, efficient, and inexhaustible energy. In an increasingly hotter world with less predictable weather, this way of harnessing abandoned excavations to promote geothermally opens up an opportunity to turn old mines into a renewable resource.


Information obtained from CNBC.