Three such heat pumps (Picture 2).are feeding a district heating system with 27 MW heat. The heat is generated from the return flow of a district cooling system. Approx. 15 MW cooling, produced by the heat pumps is fed into the district cooling system.

Several areas of  Stockholm are supplied mainly by the spill heat from the cleaned waste water  and a large number of consumers are even connected to a district cooling system [12].

An efficient application of this technology requires a clear responsibility for operation. Continuous assessment of how best to integrate the heat and cooling gained by the use of this technology, into the existing heat and cooling supply system, is essential. Therby it is necessary to examine and consider, how each part of the existing production system ,using primary energy resources, will be gradually integrated when replaced.  At the same time new users for the possible surplus heat/cooling should be found.

In the case of periods when the heat and/or cooling are not required immediately, very efficient storage systems for either seasonal or day/night have been developed and are in use [13].

The involvement of energy specialists and the application of energy contracting makes it easier to implement such energy systems [14].

Translation of the texts in the picture 1

Wärme vielfältigen Ursprungs       
bisher entsorgt oder nicht erschlossen   
Wärme für mannigfaltige Anwendung     
Im Wert zwischen 3 und 6    
Antrieb mit Gas oder Elektrizität 1    

anwendungsfähige Kälte     
Weitere Nutzen         

Heat pump application
Heat from various sources
spilled but not used yet
Heat for diverse applications
equivalent to 3 - 6
electrically or gas powered  1
applicable cooling
additional use
Return on Investment  (RoI)

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