In "Dirty old mines could be a source of clean new energy," CBC's Bob McDonald writes about using abandoned coal mines for geothermal energy.
"In a strange twist of irony, abandoned coal mines that once produced among the dirtiest fossil fuels are starting to be exploited for clean energy.
Water that has seeped into the mines, and has been naturally warmed by heat from the Earth's core, can be used to provide low carbon heat and clean energy storage.
This isn't exactly a new idea, but in our continued search for clean energy, engineers in Canada, the U.K. and several European countries are taking another look at mine water as an underutilized resource.
This is a version of geothermal energy, which has been seen as having significant potential as an alternative energy source.
The way geothermal energy typically works is by exploiting the fact that the earth gets warmer the deeper you go. Energy is harnessed by drilling into the earth, where water is circulated deep underground through a bore hole and heated. The heated water is then pumped back up, and used for warmth or for generating electricity.
Using old mines allows you to skip a step or two. The large, deep holes in the ground are already there. After mines are abandoned, water tends to naturally fill in the chambers and tunnels, and it's heated by the Earth."