Coal mines helped fuel the industrial revolution in the UK 200 years ago. Coal was plentiful, easy to access, and provided cheap energy to make England and Scotland an economic powerhouse. However, burning coal produces pollution in the form of soot, sulfur compounds that degrade air quality, and of course, carbon dioxide that can cause global warming. In response, the UK has pledged to eliminate coal power plants by 2025.
That means most coal mines have been shut down and are no longer operational. These old mines, without constant pumping, become flooded with groundwater. It was this need for pumping and steam engines that created the whole field of thermodynamics, At between 50 and 90 meters (150 to 300 feet), the temperature of the water in the mines is around 12°C (54°F), which is 2-3°C warmer (4-5°F) than typical groundwater.
The Glasgow GeoEnergy Observatory has been conducting research into how the old mines are connected in the Glasgow area to see how withdrawing water from the mines might provide a source for geothermal heat pumps. Using heat from the ground, it is possible to efficiently heat homes, without the burning fossil fuels. The mines provide a ready source of water that naturally replenishes itself. A geothermal heat pump often has a COP of at least 3, making it 4 times more efficient than natural gas.
Since about 25% of homes in the area sit on top of an old coal mine, the potential is tremendous. Pilot scale installations are being considered. It is ironic that a fuel that powered the industrial revolution, and then was discontinued because it was harmful to the planet, might help to heat homes more efficiently in the future. – Steve Terry, DTC HVAC & Refrigeration Instructor
