Impressive natural phenomena thousands of metres below the earth
Hot subterranean water is to be expected in the kind of karstified limestone that lies deep below large areas of north-western Europe. Limestone contains the necessary cavities. Over millions of years, water flowing into and infiltrating such crevices gradually wears away the limestone and creates cavities. The water there already has a temperature of over 50 degrees and, at a depth of four kilometres, it can reach as high as 130 degrees. Hot water from a depth of up to 3.6 kilometres is already being sourced from carboniferous limestone in Belgium and the Netherlands and used to run successful geothermal plants. The DGE-ROLLOUT project will benefit from the very valuable experience and insights of that initiative.
The underground strata of North-Rhine Westphalia include karstifiable carboniferous rocks (limestone and dolomite rocks) in three different stratigraphic sections and thus at three different depth levels. Limestone lies in the chalk layer at a depth of about 2.5 kilometres, while carboniferous limestone and resedimented carbonates lie within the carbon layer at a depth of about five kilometres, and Devonian reef limestone lies at a depth of up to six kilometres.