Förutsättningar för geoenergi till idrottsanläggningar i Kallerstad, Linköpings kommun : en förstudie

Sammanfattning: Because of the sun and geothermal heat the ground has two natural recourses for heat energy, and since the ground changes temperature slower than the air it has a more even temperature fluctuation. This is positive for the use of geothermal energy which is a renewable method that has been given more attention lately due to it positive environmental effects. The term renewable geothermal energy includes two different methods, shallow and deep geothermal energy. Deep geothermal energy is based on utilization of the heat produced inside the earth, mainly due to radioactive decay. Because the temperatures in the earth wants to be balanced the heat flows towards the earth surface. This results in a geothermal gradient which means that the temperature progressively gets higher further in towards the earth core. To utilize deep geothermal heat a hole is drilled from which warm geothermal water is taken. Shallow geothermal heat utilizes the upper part of the ground which is more affected by the sun and less by the geothermal flow. The systems can be designed in more than one way. The energy can be transported from the ground by providing it with collectors. By circulating a fluid in the collectors heat or cold is obtained and can be distributed to a needing facility. A more effective alternative to collectors is utilizing of groundwater. The groundwater changes, just like the earth, temperature slower than the air. By taking the water directly from the ground and extract the energy from it, no collectors is needed. An important part in the choice of solution is the geological factors. Even if groundwater methods are a more effective solution it can’t be applied all the times because of the lack of aquifers. To this all the environmental and juridical factors shall be considered when selecting method. As a consequence of all the things that has to be considered it is important to make a feasibility study before the geothermal system is being built. In Kallerstad, Linköping, sport facilities which are in demand of both heat and cold are located. When the cooling machines are running excess heat is created. This heat is today released into the outside air for no use. The situation has been given attention and has resulted in this essay which aims to give the facilities an alternative for energy source that both makes the environment better and lower the energy costs. The essay is based on literature and describes the possibilities for the investigated buildings to cover their energy demand with geothermal methods. The conclusion from this work is that the most effective alternative in this case is a borehole thermal energy storage. Any calculations on costs or emissions have not been done, but the investigation implies that the system will be successful. However, some things remains to be investigated before any constructing of the system can start. What clearly can be said though is that the system only should be fitted to support the studied ice facilities with their energy demand, the investigated soccer stadium has, as it appears today, low potential to cover its energy demand with geothermal heat.