||Flooded former coal-mines of Springhill, Nova Scotia, contain about 4,000,000 m3 of water which is recovered at the surface at a temperature of about 18oC. The heat in the water is derived from the normal heat of the rocks, and the contribution from chemical heating is negligible. Water is used as the input to heat pumps for heating and cooling industrial buildings. Annual heat exchange with the mine by the largest user puts more heat into the mine in summer than is taken out in winter. Other buildings may be a small net drain of heat, so that many systems could operate indefinitely, without significant depletion of the heat source. Initial costs of heat-pump installation are higher than the costs of conventional oil furnaces, but in Springhill operating costs of geothermal heating are substantially lower than heating by fuel oil. There is a net saving in the emission of carbon dioxide to the atmosphere.