Coal mines are finding a second life as companies invest in repurposing huge, disused coal sites into geothermal power projects. In the U.K., the government and energy companies have been discussing the idea for several years, and it seems to be gaining momentum with the launch of the first geothermal mine projects this year. Energy companies have realised the potential of flooding abandoned coal mines to provide vast quantities of geothermal power, as water in coal mines can reach a temperature of up to 20 degrees Celsius. Mine water geothermal…