Other systems

District heating

District heating pipeline in Austria with a length of 31 km ^[27]

Main article: District heating

District heating or teleheating systems consist of a network of insulated feed and return pipes which transport heated water, pressurized hot water or sometimes steam to the customer. While steam is hottest and may be used in industrial processes due to its higher temperature, it is less efficient to produce and transport due to greater heat losses. Heat transfer oils are generally not used for economic and ecological reasons. The typical annual loss of thermal energy through distribution is around 10%, as seen in Norway's district heating network.^[28]
District heating pipelines are normally installed underground, with some exceptions. Within the system, heat storage may be installed to even out peak load demands. Heat is transferred into the central heating of the dwellings through heat exchangers at heat substations, without mixing of the fluids in either system.

Beer

Thor Pipeline in Randers, Denmark

Bars in the Veltins-Arena, a major football ground in Gelsenkirchen, Germany, are interconnected by a 5-kilometre (3.1 mi) long beer pipeline. In Randers city in Denmark, the so-called Thor Beer pipeline was operated. Originally, copper pipes ran directly from the brewery, but when the brewery moved out of the city in the 1990s, Thor Beer replaced it with a giant tank.
A three-kilometer beer pipeline was completed in Bruges, Belgium in September 2016 to reduce truck traffic on the city streets.^[29]

Brine

The village of Hallstatt in Austria, which is known for its long history of salt mining, claims to contain "the oldest industrial pipeline in the world", dating back to 1595.^[30] It was constructed from 13,000 hollowed-out tree trunks to transport brine 40 kilometres (25 mi) from Hallstatt to Ebensee.^[31]

Milk

Between 1978 and 1994, a 15 km milk pipeline ran between the Dutch island of Ameland and Holwerd on the mainland, of which 8 km beneath the Wadden Sea. Every day, 30.000 litres of milk produced on the island were transported to be processed on the mainland. In 1994, the milk transport was abandoned.^[32]