HOT|COOL NO.4/16 - "From one generation..."


By René Thiemke, M.Sc. Project manager and responsible for planning the steam conversion project in HOFOR (DK21)

HOFOR is covering nearly all the expenses regarding conversion of the customers and the piping. A few larger customers (e.g. hospitals), with more than one boiler room, will have to pay for the conversion of all their boiler rooms. HOFOR, however, will pay for the piping between these boiler rooms. The steam conversion project was initiated in 2007 and had a slow progression converting only 10-50 customers annually until 2012. In 2012, a renewed business case was calculated, showing further savings above 13 m Euro, by speeding up the project by 4 years and terminating the steam supply system in 2021, hence the name - DK21. Since 2013, 110-140 steam customers have been converted annually. Besides conversion of 1,300 customers, it is also necessary to establish 95 km of new pipelines for district heating. In 2016 a new tunnel for supply of heat to the center of the city, below the Copenhagen harbor was built. The total costs were close to 16 m Euro. The below photo shows work on the tunnel in progress.

HOFOR – Copenhagen’s utility company - has an ambition to supply Copenhagen with district heating based on sustainability, with reliability and as cheap as possible. This ambition is one of the main reasons for carrying out the steam conversion project in Copenhagen – known as DK21. In 2007, HOFOR decided to terminate the steam supply to 1,300 customers over a period of 18 years and instead supply the customers with water-based district heating. The steam supply would gradually be reduced and the last customer would be converted from steam to water in 2025. The decision to terminate the steam supply was based on socio- economic assessments showing savings above 100 m Euro in a period of 45 years. Figure 1 shows the socio-economic benefits from the conversion project.

Figure 1

These savings are primarily related to reduced cost by producing hot water rather than steam. Maintenance costs of a steam supply system are also much higher than the costs of maintenance of a similar water based district heating system. To a less degree, savings are also related to the lower temperature of the water compared to the steam. The total budget of the steam conversion project in Copenhagen (DK21) is 280 m Euro. This budget covers expenses regarding conversion of all the steam customers, piping and reconstruction of some power plants. Besides being a great business case as well as great socio- economic value, DK21 also has a significant influence on the ambition of the city of Copenhagen to achieve CO2 neutrality in 2025. Along with a new biomass-fueled combined heat and power (CHP) plant (BIO4), which is another key project in HOFOR, it will be possible to make better use of CO2 neutral baseload heat, leading to CO2 reduction. This makes DK21 a project with high political interest.

Tunnel below the harbor, for transportation of heat to the center of Copenhagen.

Piping in Copenhagen has been and still is a huge challenge. The urban infrastructure is overloaded due to several piping projects spread around the entire city. In general, around 10 km of district heating pipes are established annually in DK21. Therefore, the focus has been on coordinating piping with other HOFOR projects and municipal renewal of roads. Safe supply of heat – steam and water A significant focus point in DK21 is the total load of all the customers as well as the necessary production capacity to satisfy these demands. The total load of all 1,300 customers is approximately 700 MW corresponding to a heat production capacity at approximately 300 MW.

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