Geothermal resources in the deep subsurface in many parts of Denmark have the potential to form a central component in the future Danish energy supply for district heating. Geothermal energy is sustainable and environmentally friendly and independent of climatic and seasonal variations, in contrast to solar and wind energy. Furthermore, geothermal plants may be integrated with other green energy supplies. The sandstone reservoirs from which the warm geothermal water is extracted may also act as temporary storage for excess heat e.g. from industrial production processes or from solar-heated water in summer periods when the demand for heating is low.