Fluid chemistry and impact of different operating modes on microbial community at Neubrandenburg heat storage (Northeast German Basin)

Abstract

The efficient use of energy is an important issue of public interest. In the Neubrandenburg heat storage surplus heat from a gas and steam cogeneration plant is stored in an aquifer system for use of the stored energy during times of high heat demand. The reliability of such a plant can strongly be influenced by microbial communities. Therefore, biogeochemical monitoring of the heat storage of Neubrandenburg was conducted from March 2006 to January 2010 to characterize the natural variability of prokaryotic life by way of phospholipid fatty acid (PLFA) analysis and the availability of electron acceptors (e.g. sulfate) and donors [e.g. dissolved organic carbon (DOC)] under different operating modes of the plant. Analysis of the fluid chemistry showed that a sufficient amount of electron acceptors (sulfate ca. 1g/l) and donors (DOC up to 19mg/l) for potential microbial respiration and energy consumption is present. Phospholipid analysis of filter samples from the heat storage revealed a viable microbial community in the plant with adaptation to changes in the operating mode (charge/discharge) and associated variation in temperature (45–73°C). The PLFAs mainly influenced were saturated and branched FAs, most likely reflecting temperature adaptation by a variable microbial community in different parts of the heat storage. Furthermore, branched monoenoic FAs indicated the presence of sulfate-reducing bacteria within the plant.