Waste heat storage and utilization for the case of National Veterinary Institute (SVA), Uppsala, Sweden

Abstract: The incineration furnace at National Veterinary Institute (SVA) in Uppsala, Sweden, runs approximately 2,150 hours a year and generates a large amount of waste heat. Some of this heat is partially recovered, and is used for heating one of the main buildings during the furnace operation. However, around 2,000 MWh is wasted annually due to unavailability of any storage system. This wasted heat is approximately equivalent to the heating demand of 160 average Swedish single-family houses. This work aims to investigate different options allowing to use the waste heat as an energy source in neighbouring buildings and reduce the amount of purchased heating energy. The study initiates with the quantitative analysis of available waste heat and heating demand of nearby buildings. Based on this analysis, four options for the management and use of excess waste heat have been selected for detailed evaluation. The first option considered in this work is to use a storage tank to provide the main building with heating during the furnace non-operating time. For this option, special attention has been paid to the tank sizing technique. The second option studied in detail in this work is to maximize the instantaneous use of waste heat by providing direct heating to nearby buildings. This implies the supply of waste heat directly to the buildings during the furnace operating time. In this context, a strategy has been developed to determine the optimal order for connecting different buildings depending on their demand profiles and distance from the furnace. In the third option, the instantaneous use of waste heat and hot water storage tanks has been studied simultaneously in various combinations. Finally, in the fourth option an underground thermal energy storage (UTES) system assisted by a ground-source heat pump (GSHP) has been considered for seasonal heat storage. The performance of the UTES and the GSHP system has been optimized by evaluating different strategies to maximise the source-side entering temperature to the heat pump. All the above-mentioned options have been implemented in the building energy simulation program IDA ICE (Advanced level). For each option, the overall energy performance and corresponding energy savings have been evaluated. The economic feasibility of each option has been assessed and compared to other options based on life-cycle cost (LCCs) analysis. Overall, this study contributes to the understanding of heat management between different buildings and underlines the importance of demands and availability analysis to determine the optimal solution.