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, EstoniaLCA OF COMBINED HEAT AND POWER PRODUCTION AT HELLISHEIÐIGEOTHERMAL POWER PLANT WITH FOCUS ON PRIMARY ENERGY EFFICIENCYMarta Ros Karlsdottir, Olafur Petur Palsson, Halldor PalssonUniversity of Iceland, Faculty of Industrial Engineering, Mechanical Engineering and Computer Sciencemrk1@hi.isABSTRACTThe aim of the study is to calculate primary energyfactors, f p , stating the primary energy efficiency as wellas factors for CO 2 emission, K, for geothermalcombined heat and power production at the HellisheidiCHP plant in South-West Iceland. These factors statehow much primary energy consumption and CO 2emissions result from the production of 1 MWh of heatand electricity due to geothermal utilization. Methods oflife cycle assessment (LCA) are used to calculate thesefactors by taking into account all energy and materialstreams to and from the CHP plant during constructionand operation. The results show that producing heatand electricity in a combined heat and power plantminimizes the primary energy factor for the electricitygeneration and produces a relatively low primaryenergy factor and CO2 production factor for the heatgeneration process. From the results, it can also beseen that life cycle assessment is a useful method toevaluate the total impacts of the geothermal energyconversion process, especially for the emission ofgreenhouse gasses during the lifetime of theproduction facilities. The experience in this study alsodemonstrates that the method can equally be used forprocesses as it is commonly used for the analysis oftotal impact of products.INTRODUCTIONThe calculation of primary energy and CO 2 productionfactors for geothermal power production has had littleattention while factors for some other types of energytechnologies such as hydropower, nuclear and coalfired power plants have been developed during therecent years. The importance of these factors is statedmainly in the new recast of Directive 2002/91/EC of theEuropean Parliament and of the Council on the energyperformance of buildings [1]. There it is stated thatbefore the end of year 2010, all new building occupiedby public authority should be issued energyperformance certificates showing these factors, basedon the energy mix used by the building and thebuildings‘ energy performance.At present time, geothermal power plants are situatedin 24 countries [2] and a total of 78 countries havereported direct use of geothermal energy [3]. Withincreasing fossil fuel prices and focus on renewableenergy sources, these power plants producing ―green184energy‖ become more viable in various locationsaround the world. It is thus important to investigatetheir primary energy efficiency and environmentalimpact for comparison with other energy conversiontechnologies. These energy performance indicatorscan be used to help decision making of futuredevelopments, policy making and energy rating ofbuildings.Countries that have access to geothermal areas andproduce power by geothermal utilization within theEuropean Union (EU) are: Austria, France, Germany,Greece, Hungary, Italy, Netherlands, Portugal,Romania, Slovakia and Spain. Other Europeancountries such as Iceland and Turkey, which are notcurrent member states of the EU, also utilizegeothermal energy extensively [2]. Also, 32 Europeancountries use geothermal energy directly for variouspurposes such as district heating [3]. Thus, electricityand heat based on geothermal energy are a part ofEurope‘s energy mix. For countries using geothermalbased power and/or heat and complying to EUlegislation, it is therefore important to have easy accessto standardized factors accounting for the primaryenergy efficiency and CO 2 emissions from geothermalbased heat and power.The aim of this study is to produce standardized factorsfor primary energy efficiency (f p ) and CO 2 emission (K)for geothermal heat and power production.ENERGY PERFORMANCE INDICATORS FORPRIMARY ENERGY CONSUMPTION AND CO 2EMISSIONSThe primary energy factor is defined as the ratiobetween the total primary energy inputs involvingenergy production to the actual energy delivered to theconsumer. According to [4], it should always accountfor the extraction of the energy carrier and its transportto the utilization site, as well as for processing, storage,generation, transmission, distribution and delivery.There are two primary energy factors defined: Total primary energy factor, accounting forprimary energy use of both renewable energysources and non-renewable sources. Non-renewable primary energy factor,accounting only for the primary energyconsumption of non-renewable energy sources.This factor is used when expressing only the use of