Abstract
Thermal energy for space heating and for domestic hot water use represents about a third of the overall energy demand in Germany. An alternative to non-renewable energy-based heat supply is the implementation of closed and open shallow geothermal systems, such as horizontal ground source heat pump systems, vertical ground source heat pump (vGSHP) systems and groundwater heat pump systems. Based on existing regulations and local hydrogeological conditions, the optimal site-specific system for heat supply has to be identified. In the presented technical feasibility study, various analytical solutions are tested for an urban quarter before and after building refurbishment. Geothermal heat supply rates are evaluated by providing information on the optimal system and the specific shortcomings. Our results show that standard vGSHP systems are even applicable in older and non-refurbished residential areas with a high heat demand using a borehole heat exchanger with a length of 100 m or in conjunction with multiple boreholes. After refurbishment, all studied shallow geothermal systems are able to cover the lowered heat demand. The presented analysis also demonstrates that ideally, various technological variants of geothermal systems should be evaluated for finding the optimal solution for existing, refurbished and newly developed residential areas.
Highlights
In 2016, the annual energy consumption for space heating and domestic hot water (DHW) in Germany was 2987 PJ, which corresponded to approximately a third of Germany’s total energy consumption
Our results show that standard vertical ground source heat pump (vGSHP) systems are even applicable in older and non-refurbished residential areas with a high heat demand using a borehole heat exchanger with a length of 100 m or in conjunction with multiple boreholes
We considered three different shallow geothermal systems, namely horizontal and vertical ground source heat pump as well as groundwater heat pump (GWHP) systems
Summary
In 2016, the annual energy consumption for space heating and domestic hot water (DHW) in Germany was 2987 PJ, which corresponded to approximately a third of Germany’s total energy consumption. For space heating and DHW, only 15% of the energy consumption was provided by renewable energies (BMWi 2018). Among this 15% portion, shallow geothermal energy systems are appealing, since they are continuously available. Lund and Boyd (2016) showed that 149.1 million tonnes of CO2 could be annually saved by the direct utilization of geothermal energy. Bayer et al (2012) estimated that the potential heat supply by ground source heat pump (GSHP) systems for 19 European countries is 100,000 TJ, corresponding to CO2 savings of 3.7 million tonnes. There is a great potential for geothermal energy systems to lower current greenhouse gas emissions
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