Geothermal energy refers to the use of heat from within the earth. In broad terms, it may be assumed that the temperature below the earth increases by about three degrees Celsius per 100 m depth.
Heat can be recovered from near the surface by extracting it from the upper layers of the earth or from sump water pumped out of open-cast mines to keep them dry.
Because the temperature of the water close to the surface is not sufficient for most purposes (i.e. heating), the temperature must be increased further using a heat pump.
Learn more about our projects to make use of sump water.
Heat from great depth
If heat is recovered from greater depths, i.e. 2,000 to 4,000 m, temperatures in excess of 100°C may be expected, and the heat can then be used directly.
Drilling bore holes as deep as this is, of course, labour-intensive and costly, which means accurate inspection of the subterranean layers must be performed first.
Learn more about our Weisweiler geothermal project.