By 2050, 7 million homes and 1 million buildings will need natural gas. To achieve this, buildings will have to be insulated and sustainable heat and electricity will be used. 1.5 million existing homes must be made sustainable by 2030. Since the imposition of this measure, everyone has been diligently looking for other forms of energy sources. In Heerlen, long before the Climate Agreement, the municipality had literally started drilling for sustainable energy, namely the energy in the geothermal wells beneath its feet. The former mine corridors, the basis of what is now an innovative circular energy network, contain hot water. This low-temperature source, which provides heat but also coolness to homes, offices, shops and industrial companies, also uses residual heat from the surrounding area and, when there is less demand, ensures that residual energy is stored in existing underground corridors or power plants with buffer vessels. Thanks to innovation, the network can now also be seen separately from the underground mine corridors, by placing prefabricated (eco) barrels in the ground, where there are no mines. The circle of (water) energy is complete (everywhere)!