The Geothermal Alliance Bavaria research network has successfully established in its first four-year funding phase from 2016 to 2019. Through the interdisciplinary research of engineers and geoscientists, important questions in the field of deep geothermal energy could be answered in cooperation with geothermal plant operators and authorities. The holistic research approach of the GAB has been proven and enables a close cooperation and consideration of deep geothermal energy beyond the boundaries of the respective sub-disciplines.
Subproject “Efficient. Heat transition through intelligent use of deep geothermal energy”
The subproject deals with the mechanical, electrical, and thermodynamic components of geothermal energy systems. The overarching goal of the research is to improve geothermal heat utilization and thereby increase economic efficiency. In addition to new approaches for submersible centrifugal pump (SCP) motors, which promise higher efficiency and thus lower power consumption, experimental investigations of new cycle processes are being carried out on a test bench set up specifically for this purpose. The technical feasibility of triangular cycles is being investigated and new working media are being compared in terms of their applicability and efficiency. This work is largely based on the findings and results of the first funding phase of the GAB and makes use of existing systems and approaches. In addition, new concepts using CO2 as a heat transfer and working medium are being pursued in order to take novel approaches into account. In addition to pump motor development, a new concept is also being pursued for sorption chillers, which can use decentralized geothermal district heating to generate cooling for room air conditioning.
Subproject “Regional. Systematically exploring new potential”
In order to systematically explore new potential, previously unused geothermal resources in northern Bavaria are to be intensively investigated and locations in southern Bavaria that are optimally suited for proven geothermal resources are to be identified for a potential analysis of district heating supply. In order to enable the use of deep geothermal energy in the crystalline rock of northern Bavaria, suitable locations will be identified in the area of the geothermal heat anomaly in the Bamberg-Coburg region and intensively investigated using a combination of geophysical measurements, hydraulic characterization in the field laboratory, and numerical modeling. The use of deep geothermal energy in Bavaria currently focuses on the hydrothermal resources in the Molasse Basin in southern Bavaria. However, the potential, particularly for district heating, is far from being fully exploited. For this reason, two locations in the Molasse Basin that are ideally suited for geothermal district heating are to be identified for a detailed analysis of the above-ground potential.
Subproject “Social. Climate protection through safe technology”
The subproject addresses the issue of social acceptance of deep geothermal energy. To this end, aspects of safety and environmental protection in geothermal projects are examined in detail. Induced seismicity plays a particularly important role in safety considerations. Noticeable microseismic events that occurred in the Molasse Basin during geothermal production have led to reservations about the technology in the past. As part of the subproject, simulations and experiments will therefore be used to conduct a risk analysis and probability assessment of the occurrence of possible building damage due to repeated microseismic events. A second pillar of this research project addresses the question of how to prevent noticeable seismic events. In addition to safety issues, the “social” subproject aims to further develop comprehensive life cycle analyses in deep geothermal energy.
Subproject “Long-term. Ensuring sustainable thermal water production”
This subproject will focus in particular on minimizing the drilling, discovery, and production risks associated with hydrothermal geothermal energy in the Bavarian Molasse Basin, as well as on sustainable reservoir management. To this end, a holistic approach is planned that will consider the interactions between the various influencing parameters (temperature, hydraulics, stresses/mechanics, hydrochemistry) across all scales. In particular, the Bavarian Molasse Basin will be investigated as a complete geothermal system. The influences of the various structural units of the Bavarian Molasse Basin on the exploration, development, and productivity of the Malm reservoir will be investigated. The petrophysical and geomechanical characterization of the reservoir and the interacting structural units of the Bavarian Molasse Basin based on drilling data, production data, drill cores, analog samples, and field laboratories will play a central role in this. The findings will then be applied in site-specific studies for the development of forecasting and monitoring tools to improve reservoir engineering and monitoring, ensure sustainable reservoir management, and reduce drilling risk.
Drill heads before use at a geothermal drilling site (Photo: Geothermal Alliance Bavaria)
Subproject “Reservoir characterization”
Targeted investigation of local and regional differences in terms of geophysical, geomechanical, structural geological and hydraulic reservoir properties.
Objectives:
- Minimization of geothermal exploration risks in the South German Molasse Basin
- Minimization of uncertainties in reservoir engineering and long-term operation of geothermal plants.
Vibrotruck (Photo: Dr. Wolfgang Bauer)
Subproject “PetroTherm”
Development and support of a petrothermal project in the Bamberg-Coburg area under the leadership of the GeoZentrum Nordbayern.
Objectives:
- Determination of an optimal drilling location by evaluation of 2D-seismic profiles
- Investigation of stress conditions in the targeted area and the fracture behavior of selected rock types
Scalings (Photo: Prof. Dr. Thomas Baumann)
Subproject “Operational safety of the thermal water circuit”
The project bundle “Operational safety of the thermal water circuit” addresses
- The formation of scalings in the thermal water circuit
- Investigation of the kinetics and making forecasts.
- Investigation of technical measures for control and prevention
- The control and modeling of the submersible centrifugal pump
- Development of a detailed dynamic model
- Development of intelligent control
- Investigation of a model-based condition monitoring
Normalized gross power as a function of the outside air temperature and the normalized thermal water volume flow of a geothermal power plant of one year (source: Matthäus Irl).
Subproject “Monitoring”
Development of an online monitoring tool for geothermal plants.
Objectives:
- Acquisition and evaluation of operating data
- Definition of a uniform system of key figures
- Implementation of a sound reporting function
- Improvement of the comparability and evaluability of different geothermal plants
Inside a geothermal power plant (Photo: Geothermie-Allianz Bayern)
Subproject “Efficient and Flexible Power Plants”
Realization of a holistic approach to improve the economic viability and plant efficiency of the aboveground power plant components.
Objectives:
- Holistic investigation of innovative concepts, working fluids/fluid mixtures and CHP variants
- Implementation and construction of a ORC test facility
- Examination of flexibility and operational readiness
- Investigation of the future role of geothermal energy in the case of significant expansion of installed capacity as well as in a capacity market