How does District Heating work?
Through a district heating network, the heat producing plant pumps heated supply water to consumers where it is used as room-/floor-heating and to generate domestic hot water. The domestic hot water gets heated in a heat exchanger in which the heated supply water transfers its heat to the water coming out of the taps.
For room heating, the supply water might be used directly. Alternatively, a heat exchanger could also transfer the heat to an internal circulation. The supply water – which is now cold because the heat has been transferred to domestic hot water and room heating – then returns to the district heating plant. The district heating supply water circulates endlessly in a closed pipeline.
Some district heating systems use steam as medium for heat distribution instead of water. This is to achieve higher supply temperatures, which are often necessary for industrial processes. A disadvantage of steam is that it has higher heat losses than water.
Environmentally Friendly & Energy-Efficient
Due to simultaneous production of heat and electricity in combined heat and power plants, district heating is very energy-efficient. By implementing renewable energy sources and utilizing waste heat generated by industry the environmental gain by district heating is further evident. This kind of energy utilization is beneficial for both environment and society in general.
Compared to individual heating systems the district heating plants are better at reducing emissions of hazardous compounds since they have more advanced pollution control equipment and through their more controlled conditions when generating heat. Furthermore, district heating is very convenient for consumers - who hardly notice how their radiators and tap water is heated in their everyday.
District Heating in Denmark
In Denmark most district heating plants are combined heat and power plants that distribute the heat made from the surplus heat generated by the production of electricity. An example is the Sønderborg Kraftvarmeværk (CHP) in Southern Denmark on the above picture, which burns waste to generate heat and electricity.
1.5 million Danish households in Denmark's major cities are connected to collective district heating networks. This means that about 60% of the Danish population is kept warm by district heating.
Denmark is a world leader in district heating. Danish district heating technology is an important export, a fact that also benefits the Danish economy.