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Browsing by Author "Buss, Mia"

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  • Buss, Mia (2014)
    The 2020 climate and energy package is obligatory for the EU to increase renewable energy usage. Because of this and a trend of increasing energy prices, Finland has started to develop geothermal energy more since the year 2000. Geothermal energy is heating- and cooling energy which comes from the bedrock, earths surface layers, water systems and from surface sediments in water systems. This research is about geothermal energy, particularly groundwaters potential to make energy for heating and cooling in two different cities in Finland. Generally research assumes that urbanization and the 'heat island' phenomenom makes groundwater warmer. This groundwater research was carried out in Lohja and Turku. There were altogether eight groundwater pipes and the groundwater temperatures were followed for 5,5 months. Two of these groundwater pipes were located in natural areas just outside of the city, temperatures of the natural area groundwater pipes were used to compare the results from the city groundwater pipes. 58 Thermochron dataloggers were installed to the groundwater pipes and they measured the temperatures every two hours from different depths. In addition there was one Thermochron datalogger in each city which took measurements of the outside temperatures. Thermochron dataloggers haven't been used for measuring groundwater temperatures over a long period of time, so it was uncertain how or if this method would succeed. Due to this untried method of research, the dataloggers were checked approximately once a month and the data extracted from them thus far. Temperature depth profiles were made from groundwater temperature results, and the possible groundwater energy results were calculated from these. Temperature results showed that urban groundwater is warmer than the natural groundwater. Natural groundwater temperatures were approximately +5.5 – 6.5 °C and +7 – 13 °C in urban areas. Results also showed a time delay between the groundwater temperatures and the air temperatures. Air temperatures decrease quite steadily from July's +18.5 °C to December's +0.5 °C. The highest temperatures of the groundwater were recorded between October and November. Thermochron dataloggers worked variably in the groundwater pipes due to the subjection of high pressures along with the lack of water resistance. Some of these dataloggers ceased to work in the midst of the research, and as a consequence results of the temperatures had to be partly interpolated. To obtain a better energy potential, the groundwater temperature should be researched for a longer period of time than 5,5 moths, thus producing a comprehensive set of results throughout the seasons bearing a strong correlation. Under the circumstances these results shows groundwater energy is viable in the local areas.