The hot water circulates between the heating plant and the customer’s premises in insulated, underground steel pipes. The pipes are laid in trenches, often with other infrastructure such as phone lines and power cables, and they suffer average heat losses of only five to ten percent. Customers use the water for heating through piped underfloor heating or radiators and for heating tap water.
Many different energy sources are used for district heating production, including waste, biofuel, heat pumps, landfill gas, natural gas, propane/butane, electricity and fuel oil. Several different energy sources may be used simultaneously in the district heating plant, which makes for stable and flexible supply of heat to customers.
Through Trondheim Energi and Skagerak Varme, Statkraft has district heating plants in Trondheim, Klæbu, Porsgrunn, Horten, Jarlsø and Tønsberg. In Sweden, Statkraft Värme AB generates 320 GWh a year from wood-pellet-fired heating plants in Kungsbacka, Alingsås, Trosa, Vagnhärad and Åmål.