Co2 based district energy system

Abstract

District energy system comprising a pipe system, end user's locations, and an optional plant for transferring an energy transfer medium between said end user's locations and/or between said optional plant and said end user's locations, characterized by the fact that said energy transfer medium is CO 2 .

1 . District energy system comprising a pipe system, end user's locations and an optional plant for transferring an energy transfer medium between said end user's locations and/or between said optional plant and said end user's locations, characterized by the fact that said energy transfer medium is CO 2 . 
   
   
       2 . District energy system according to  claim 1  comprising two main pipes extending between said end user's locations and/or between said optional plant and said end user's locations, the first main pipe containing CO 2  in liquid state and the second main pipe containing CO 2  in gaseous state. 
   
   
       3 . District energy system according to  claim 1  including at least one energy transformer, said transformer having one inlet communicating with one of said two main pipes and one outlet communication with the other one of said two main pipes. 
   
   
       4 . District energy system according to  claim 1  wherein at least one end user location comprise one or several outlets, e.g. valves, which are adapted for fire extinguishing. 
   
   
       5 . District energy system according to  claim 1  wherein at least one end user location comprise one or several inlets which are adapted for bringing external CO 2  into said district energy system. 
   
   
       6 . District energy system according to  claim 1  wherein the pressure level in both main pipes is very similar, the pressure in the first main pipe being slightly higher than the pressure in the second main pipe. 
   
   
       7 . District energy system according to  claim 1  wherein the pressure level in both main pipes is the pressure corresponding to a CO 2  saturation temperature in the range of 15° C. to 18° C. 
   
   
       8 . District energy system according to  claim 1  wherein one of said two main pipes is a supply pipe and the other of said two main pipes is a return pipe. 
   
   
       9 . Use of a district energy system as defined in  claim 8  characterized by the fact that, when the heating requirements are higher than the cooling requirements (e.g. in winter), said second main pipe is used as supply pipe and when the cooling requirements are higher than the heating requirements (e.g. in summer), said first main pipe is used as supply pipe. 
   
   
       10 . Use of a district energy system according to  claim 9  including at least one heat-exchanger for providing heating or hot water wherein gaseous CO 2  follows a circuit in which it is successively compressed and passed through said heat-exchanger, an expansion valve and a separator, the resulting CO 2  liquid phase being sent to said first main pipe and the remaining gaseous CO 2  being redirected in said circuit.