The operational reliability of the geothermal used groundwater systems investigated with special consideration to microbial activity and particle relocation – screening on the representative sites (Aquiscreen)
The relevancy of alternative energy resources is still increasing because of limited fossil fuels and the negative effects of climate change due to the accumulation of CO2 in the atmosphere. Therefore the utilization of subsurface stored energy arouses increasing interest of scientists. The research project AquiScreen investigates the operational reliability of geothermal used groundwater systems under microbial, geochemical, mineralogical, and petrologic aspects. The screening on the 8 different geothermal systems aims to identify the decisive parameters for the monitoring.
Microbiological analyses based on fluid and solid phase of geothermal systems are utilized to evaluate the impact of microbial populations on such systems. Therefore the f luid and filter samples were investigated based on 16S rDNA to characterize the microbial biocenosis of the geothermal aquifer and its long-term changes resulting from the utilization of geothermal systems as an energy source or –reservoir . The identification of microorganisms enables the correlation to metabolic classes and provides information about the biochemical processes in the deep biosphere. The quantification and isotopic analyses of the dissolved organic matter give further information about the potential carbon sources and metabolites for the microorganisms. The analysis of phospholipids, indicators of living organisms, enables further characterisation of the microbial community. Furthermore, the precipitate particles on the geothermal systems would be analyzed. The corporate analyses provide fundamental data on the predominant microbial processes and changes in those processes due to the utilization of geothermal systems.
The process monitoring enables early detection of the microbial colonization as well as corrosion and precipitation processes. A timely counteraction against these processes allows an optimization of the geothermal processes, which are used for the energy generation and conservation.
Würdemann, H., Vieth, A., Miethling-Graff, R., Seibt, A., Wolfgramm, M.: Mikrobiologie geothermisch genutzter Aquifere: Untersuchungen zum Einfluss auf die Betriebssicherheit. 9. Geothermische Fachtagung "Mehr Energie von unten". Karlsruhe, 15.-17. November 2006, Veranstalter GTV .