12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaAPPLICATION OF THE PRIMARY ENERGYCONCEPT ACCORDING TO EN 15603Primary Energy ConceptThe EU standard EN 15603 [2] handles the energyperformance of a building as a whole and givesguidelines how energy use and production of a buildingshall be calculated. In order to aggregate the differentforms of energy produced and used within the building,primary energy (PE) and CO 2 emissions areaccumulated and expressed by means of primaryenergy factors (PEF) and CO 2 emission coefficients,respectively. PE is energy that has not been subjectedto any conversion or transformation process [2]; it ishence not yet extracted from the source. In the PEapproach described in EN 15603, all energy carriersinvolved in the generation process are retraced to theirsources and all energy needed to deliver the finalenergy product are aggregated to the total PEconsumption and CO 2 emissions. Thus the PEapproach applies the holistic principles of life cycleassessment to an energy rating procedure. By retracingenergy consumption to the source, the systemboundaries automatically include the whole world, andthus depict the real impact of the system concerningenergy consumption and CO 2 emissions.In the power bonus method f El. is defined as the PEF ofthe electricity that is thought to be replaced by thepower generated in the CHP plant (for instance, in thisstudy the average power generation efficiency inFinland is used). This allocation pays attention to thefact that the co-generated electricity is more sustainabledue the CHP process‘ high overall efficiency. The PEFof the DHN can thus be determined according to;fDHifF , i EF P QDHfEl .As production of products other than electricity is notdefined in EN 15316-4-5 the power bonus method hasbeen extended by regarding the produced pyrolysisslurry as a ―bonus‖ as well. The PEF of the pyrolysisintegrated CHP plant is thus calculated as:fDH fF , i EF, i P fEl .iQDH EPyro fPyroPrimary Energy FactorThe total primary energy factor is the sum of all PE inputto the energy system divided by the useful energydelivered at the system border. It thus describes howmuch PE input is needed in order to obtain one unit ofenergy used and can hence be seen as an invertedefficiency.In standard EN 15316-4-5 [3] more detailed guidelinesfor the calculation of PEFs of DH systems are defined.According to EN 15316-4-5 PEFs can be calculated fora certain part of the energy system. In this study thesystem boundary comprises the power plants and theDHN.The PEF of the DHN has been calculated applying thepower bonus method. If yearly demand data of the DHNand the generation data are known, the PEF of the DHNcan be calculated by applying the so-called powerbonus method. The power-bonus method is derivedfrom the energy balance of the building which can bewritten as: fF , i EF fDHQDH PfEl .,iwhere E F , Q DH and P are the heat of the fuels used, DHand power co-generated respectively. f F,i , f DH and f El. arethe PEFs of the fuels used, the DHN and of the cogeneratedpower.172In this study PEFs as shown in table 2 have been used:Table 2: Primary energy factors and CO 2 emissioncoefficients for fuels and productsf BM2f Oil2f El.1f Pyro11.09 c CO2/BM21.35 c CO2/Oil23.11 c CO2/El.11.28 c CO2/Pyro1kg/MWh143302701 : value is calculated, 2 : value is taken from EN 15603, Annex EFuels assumed to be used are wood logs for the CHPplant and fuel oil for the heat-only/backup boiler(s) andtheir PEFs are taken form annex E of EN 15603. ThePEF of electricity production in Finland has beenderived from [10]. The PEF of pyrolysis slurry in astand-alone unit has been calculated assuming a fluegas dryer (which is considered as the drying technologymost likely to be applied) with an energy consumption of3300 kJ/kg water evaporated [9] and a heat of pyrolysisof 1.87 kJ/kg [7]. Although the standard asks for moredetailed analysis of the energy chain as e.g.consideration of transport, transmission and otherprocessing should be included, this has not beenimplemented into this study since those factors areassumed not to differ between integrated and separatedproduction of pyrolysis oil.14