Solar District Heating (SDH): Technologies Used in Large-Scale SDH Plants in Graz – Operational Experiences and Further Developments
Abstract
S.O.L.I.D. installed three large scale solar plants for feeding into the city’s district heating in Graz in recent years. These three solar plants have an annual heat production of 13,5 PJ, the city’s grid delivers 2990 PJ per year. Therefore the integration of solar thermal in a technical and economical feasible way has to meet the requirements of Graz’ existing district heating grid, which is one of the largest in Austria. The first plant, at stadium Graz-Liebenau with 1.420 m², has been for seven years in reliable operations, 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 of 250 MW) and from there the heat is distributed through the district heating grid. The latest plant, at Wasserwerk Andritz with currently 3.860 m², has a buffer storage of 60 m³ and the planning for installation of a heat pump is completed. The plant feeds into the district heating grid and supports the room heating of a large office building. This paper presents operational experiences about three different ways for feeding solar thermal energy into a large city’s district heating grid. Recent developments like buffer management for combined district heating and room heating and integration of a heat pump are outlined.