Termisk lagring vid Akademiska sjukhuset : Kapning av effekttoppar, ökad redundans och energisäkerhet

Sammanfattning: The Academic Hospital in Uppsala is a major heat energy consumer with an average consumption of 39 GWh/year in recent years, and the heat is supplied by the district heating system which is owned by Vattenfall. The purpose of this work was to investigate if a thermal storage can reduce the costs of district heating consumption and increase the redundancy at the hospital by cutting the heat demand peaks and provide back-up heat in case of district heating deliverance failures. The type of heat storage used in this study is a pit heat storage which consists of an insulated basin in the ground filled with hot water which is sealed from above with a lid that acts as an insulating layer. Matlab was used for the simulations of different storages sizes and used year 2016:s heat consumption of the hospital building B11 to see how the storage worked. The introduction of a thermal storage will increase the total sum of purchased heat for all storage sizes and the two larger storage sizes manage to cut down the heat demand peak while the two smaller storage sizes increases it slightly. This means increased annual costs for the smaller storage sizes but reduced annual costs for the larger storage sizes. However this doesn’t included the drift or the investment costs. The conclusion is that heat storage is not an economic benefit because the annual cost savings are highly dependent on Vattenfall's price model and the repayment period will be several decades long. A heat storage can be an energy-saving benefit but at a high cost.