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, EstoniaTrade-offsIn the ongoing PhD-project of the first author a cut-offrule is set to 1%. That implies that factors with lessthan 1% impact on the final result can be removed.The trade-off considerations are still an ongoingprocess, and it will be presented and documented in alater paper. According to the main hypothesis this is notmeant be developed as an optimization tool, since theintention of the ongoing PhD-project is to develop amethod describing different energy chains.A complete trade-off could preferably [32] be performedby use of computerizes programme like CORE.[http://www.vitechcorp.com/solutions/]. The complexityof the different kind of systems shows the utility valueof more than manual tools, which has been applied.Document current system designThe results of the iterative process are described in thefigures mentioned above. Only selected parts of thechosen design are illustrated in this document due tolimitation in size.The final system design is carried out according toFigure 6 for each element.CONCLUSIONBy performing a system engineering processdescribing different energy chains an outline of themodel have been developed. The method has provento be efficient in structuring the thoughts and willhopefully reduce mistakes in the future development ofthe model.The decomposition process in different subsystems isvaluable, and the generic model will be able to treatdifferent kind of energy systems and chains.The systems engineering process have demonstratedthat;1. It is possible to develop a generic method thatprovides credible data for calculating PEF-valuesand the primary energy efficiency.2. It is e.g. possible to apply the generic method onenergy systems in the Nordic region with CHPplants utilising bio based fuelThe system engineering process provides a newapproach to the design and development of a genericmodel describing PEF-values for energy systems withdifferent kind of energy carriers. The method might beused for more than systems using CHP-technologysince the model development are generic and therebyutilizes different kind of energy carriers.The method can provide detailed data (e.g. efficiency,loss etc) from the different energy chains and mix ofchains. A major challenge is the data collection, someof the parameters lack standardization. The life time ofdifferent equipment varies, the economical lifetime isoften significant lower than the actual exchange ratee.g. pipelines might have a twice times higher - morethan 60 years. The use of yearly average efficiency andappurtenant power-to-heat ratio will often increase thePEF value for the whole system due to the impact ofthe power bonus method.The reliability of the method will be influenced bypossible lack of detailed data, but based of averagedata a reliable comparison of different energy chainsmight be performed.More standardized values for some the differentparameters needs to be developed, like lifetime, heatload curves and extraction of biomass. Someadjustment will be necessary for instance for extractionwhere the transport distances are an importantparameter. The resulting model can form a basis forfuture optimization tools, since only elements withmajor influence on the PEF-values are included.ACKNOWLEDGEMENTThis paper is developed as a part of the PhD-projectPrimary Energy Efficiency (PEE) and the work title forthee PhD-Theses is "System, methods and credibledata for calculating primary energy efficiency in generaland for energy systems in the Nordic region with specialfocus on energy systems applying CHP-technology withbio based fuel in particular".The project is financed by Nordic Energy Researchwith financial support from the industry and includes sixPhD-studies carried out in the respective countries;Estonia, Finland, Sweden, Iceland and Norway. Theprojects objective is to contribute to the effort ofenhancing the primary energy efficiency (PEE) andreducing CO2-emissions in the energy sector.FURTHER INFORMATIONPhD.student Monica Berner, Norwegian University ofScience and Technology (NTNU).Address: Monica.Berner@ntnu.noREFERENCES[1] Proposal for a Directive of the EuropeanParliament and of the Council on the EnergyPerformance of Buildings Recast SEC (2008)2820, SEC (2008) 2821)[2] EN 15603 – Energy performance of buildings –Overall energy use and definition of energy ratings[3] EN 15603:2007 Energy performance of buildings –overall energy use and definition of energy ratings[4] EN 15316-1: 2007 Heating systems in buildings –Method for calculation of system energyrequirements and system efficiencies – Part 1:General37