The Biden administration recently Announce Nearly $5 billion in inflation-reducing and infrastructure laws will go to clean energy projects at former coal mines. Some will be solar farms at these sites, but there’s also a lesser-known opportunity within mines: geothermal energy.
Abandoned coal mines often fill with water after mining stops. Water contains heat from far below the surface. People can drill holes to bring heat to the surface, where it can be transferred through heat exchangers and heat pumps in buildings and homes.
The UK’s first community mine water heating scheme just became fully operational at the end of March and will eventually serve more than 1,200 homes.
“Each exploitable option presents different challenges, and there is the expense of drilling or piping the district heating network underground,” explains Gareth Farr, director of thermal and by-product innovation at the Mansfield Coal Authority in England. “But hopefully Most, if not all of these schemes can be run at a cost similar to or better than the traditional fossil fuel heating schemes we currently have.”
Geothermal energy is not new, but harvesting it from abandoned coal mines is not common, especially in the United States.
Natalie Kruse-Daniels, professor and director of the Environmental Studies Program at Ohio University, and her students are studying abandoned mines in Ohio’s Appalachian Mountains to see which mines are close enough to town , can be used for home heating.
“It’s this untapped source of energy that can reduce bills, can increase energy efficiency, can reduce dependence on fossil fuels,” said Daniels, who was fascinated by coal mines since childhood.
Geothermal energy from coal mines can be used not only to heat homes and buildings, but also to cool them. This opens up more opportunities, especially for data centers. They are among the worst carbon emitters, using a lot of energy and requiring thousands of gallons of water to cool themselves. Now, researchers in Scotland are working on how hot air from data centers can be pumped into coal mines and recycled from the water to heat other buildings.
“We can store heat in mines, and we really hope that this can actually be part of important heat storage. Of course, for many renewable energies, storage is key,” Farr explained.
At least 20 U.S. states have coal fields
With more than 4,000 abandoned mines, Ohio is rich in geothermal energy resources. In 2007, the US Department of Energy reported that the amount of water currently discharged from underground coal mines in the Pittsburgh Coal Seam alone has the potential to heat and cool approximately 20,000 homes.
So why didn’t it happen? While it’s a relatively cheap form of clean energy, location and legacy issues can be downsides, Kruse-Daniels said.
“I think some of it is invisible, out of mind, right? When we look at investment in new technology and clean energy in Appalachia, it’s limited,” Kruse-Daniels said.
Coal is controversial, so investors wouldn’t target coal regions, she said, and that would be a mistake.
“In a more unpredictable climate and a warmer world, this presents an opportunity to turn this legacy, this responsibility, into a resource,” she added.
CNBC Producer Erica Posse contributed to this article.