[{"type":"speech","title":"Heat supply by shallow geothermal energy in Karlsruhe","issued":{"date-parts":[["2018","3","21"]]},"event":"26. Grundwasser im Umfeld von Bergbau, Energie und urbanen R\u00e4umen - Tagung der Fachsektion Hydrogeologie e. V. in der DGGV e.V. (2018)","event-place":"Bochum, Deutschland","event-date":{"date-parts":[["2018","03","21"],["2018","03","24"]]},"author":[{"family":"Tissen","given":"Carolin"},{"family":"Menberg","given":"Kathrin"},{"family":"Bayer","given":"Peter"},{"family":"Blum","given":"Philipp"}],"abstract":"By employing shallow geothermal systems, heat is extracted from the subsurface and utilized for\r\nspace heating and domestic hot water (DHW). In built-up areas the available thermal energy is even\r\nlarger, if the subsurface urban heat island (UHI) effect is also considered. Increased surface\r\ntemperatures combined with underground anthropogenic heat sources, such as basements and\r\nsewage systems, can raise urban groundwater temperatures by 3 K to 7 K above those in rural areas.\r\nPrevious studies calculated the annual average anthropogenic heat flux into the ground by means of\r\na spatially resolved heat transport model (Benz et al., 2015).\r\nIn this study, the geothermal potential is compared to the energy demand for space heating as well\r\nas DHW for the urban quarter \u201cRintheimer Feld\u201d in Karlsruhe, Germany. In this quarter the housing\r\nassociation (Volkswohnung GmbH) is proprietor of 30 multifamily-houses with about 70,000 m\u00b2 of\r\nliving space. These houses were built in the 1950\/60s and meanwhile have been refurbished (Rink\r\nand Kuklinski, 2015). The calculation is based on the consumption data of space heating and DHW of\r\nall buildings before and after the refurbishment. By merging the anthropogenic heat flux and the\r\nenergy stored underground we obtain the geothermal potential. Based on these results and\r\nconsidering space availability as well as (hydro)geological boundary conditions, we determine the\r\nrequired number of open and closed geothermal systems. Furthermore, we determine how much of\r\nthe energy demand \u2013 before and after refurbishment, respectively \u2013 can be covered by one of the\r\nthree following geothermal systems: (1) horizontal ground heat exchangers (HBHE), (2) ground\r\nsource heat pump (GSHP) systems with vertical borehole heat exchangers (BHE) and (3) ground\r\nwater heat pump (GWHP) systems. Our results show that energy supplied by the HBHE is not\r\nsufficient, since the area required for the system installation is too small. Totally 90% of the heating\r\nenergy demand can be covered. Assuming a BHE length of 100 m and a spacing of 5 m, the energy\r\ndemand before and after refurbishment can be fully covered by GSHP systems. GWHP systems can\r\nonly partly cover the demand, due to the higher space demand, which is required to avoid thermal\r\ninteraction between the wells. In case of a conservative assumption (1 K plume isotherm), 6% of the\r\nenergy demand can be obtained before and 13% covered after refurbishment. Assuming a 3 K plume\r\nisotherm, an entire coverage of the demand is possible after and at 76% before refurbishment.\r\nTo conclude, GSHP systems can cover the energy demand before and after refurbishment in the\r\n\u201cRintheimer Feld\u201d and are therefore also the preferred geothermal system variant","kit-publication-id":"1000098966"}]