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, EstoniaSOLAR DISTRICT HEATING (SDH): TECHNOLOGIES USED IN LARGE SCALE SDHPLANTS IN GRAZ – OPERATIONAL EXPERIENCES AND FURTHERDEVELOPMENTSM. Schubert 1 , C. Holter 1 and R. Soell 11S.O.L.I.D. Solarinstallationen und Design GmbH, Puchstr. 85, A-8020 Graz,m.schubert@solid.atABSTRACTS.O.L.I.D. installed three large scale solar plants forfeeding into the city‘s district heating in Graz in recentyears. These three solar plants have an annual heatproduction of 15,8 PJ, the city‘s grid delivers 2800 PJper year. Therefore the integration of solar thermal in atechnical and economical feasible way has to meet therequirements of Graz‘ existing district heating grid,which is one of the largest in Austria.The first plant, at stadium Graz-Liebenau with1.420 m², has been now for seven years in reliableoperations, with very good power output data.AEVG Graz, the largest plant in Graz at 4.960 m²,feeds into the gas power station (maximum power of250 MW) and from there the heat is distributed throughthe district heating grid.The latest plant, at Wasserwerk Andritz with currently3.860 m², has a buffer storage of 60 m³ and theplanning for installation of a heat pump is completed.The plant feeds into the district heating grid andsupports the room heating of a large office building.This paper presents operational experiences aboutthree different ways for feeding solar thermal energyinto a large city‘s district heating grid. Recentdevelopments like buffer management for combineddistrict heating and room heating and integration of aheat pump are outlined.First solar thermal plants for district heating were builtin the 1970‘s in Sweden. Since then, various plantshave been built mainly in Austria, Denmark, Germanyand Sweden.Most of these solar plants feed into rather small heatinggrids or sub-grids with an annual heat delivery below50 GWh th (180 TJ). In Denmark, this market wasgrowing rapidly in recent years and is now bigger thanthe market for small-scale solar systems for singlefamilyhouses.In Graz, Austria, solar thermal plants feed into a largescale heating grid with an annual heat delivery of830 GWh th (2,99 PJ) and a maximum power of382 MW th . Technical parameters and operationstrategies in large scale heating grids are different tothose in small scale grids and solar thermal technologyhas to adopt to these circumstances.Three solar thermal plants in Graz are presented andthe way they are integrated into the city‘s heating grid.SDH PLANT DESIGNS IN GRAZ1. Feeding directly into the district heating grid– plant at stadium Graz-LiebenauThis plant is located on the roof of an ice-skating hallnext to the city‘s football stadium (Fig. 1).INTRODUCTIONFor reasons of energy security and environmentalprotection, the European Union has set a target of 1%solar fraction in district heating in 2020 and of 5% in2050 [1].Solar thermal technology is widespread in the singlefamily house sector in most European countries. Mainlyfor domestic hot water preparation (DHW), but also forroom heating (RH).In multi-family houses and for heating grids, there arenot yet as many solar thermal plants and the marketbegins to develop.Fig. 1: Aerial view of solar plant Stadion Liebenau140