Geothermal power plant Iceland
Enhanced Geothermal System (EGS)
Image: sulzer.comEarth’s crust offers a vast resource of heat that can be used and converted into energy both for electricity and heating / cooling purposes. The utilization of this geothermal energy can make an important contribution to meet the targets of the envisaged energy turnaround. So-called “conventional” geothermal plants exploiting hot hydrothermal reservoirs have long been a fully commercial contributor to the energy provision in favorable geological settings such as Iceland or Tuscany/Italy. The concept of Enhanced Geothermal Systems (EGS), however, is a much younger approach to make the heat stored in Earth’s crust available for a stable supply of heat and power, independent of specific geological conditions. Such systems offer an enormous potential for a sustainable energy concept since they provide base-load energy and therefore constitute an important cornerstone in a future energy mix as counterpart to the increasing share of fluctuating energy sources being furthermore mostly poor on CO2 emissions and practically inexhaustible.
Removed pipe section with mineral scalings
Image: T. Schäfer 2013)Scale formation processes in the surface installations of geothermal power plants may have a negative effect on power plant performance. In addition, scales formed within the geothermal water circuit frequently accumulate natural radionuclides. Consequently, scale formation may lead to dose rates, which are of radiological concern, and scales, which may have to be disposed as radioactive waste. In order to minimize these problems and to foster geothermal power plant availability, it is of major interest to understand scale formation processes and to develop methods for their inhibition.
The efficiency of geothermal utilization depends heavily upon the behavior of the fluids that transfer heat from the subsurface to the power plant, which is determined by their chemical and physical properties. In terms of the chemical properties, there are few data on the composition and stability of organic components in geothermal fluids. Currently, research at GFZ Potsdam focusses on this area and the work forms part of the EU project „REFLECT”External link (Redefining geothermal fluid properties at extreme conditions to optimize future geothermal energy extraction). Organic components such as aliphatic hydrocarbons Formiate, Acetate, and Propionate as well as aromatic hydrocarbons Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) play an important role and are frequently found in sedimentary basin fluids. They serve as nutrients for microorganisms and can affect fluid chemical properties by complexation, and fluid physical properties through decomposition with increasing fluid temperatures. While both, inorganic and organic compounds affect fluid properties, the research intends to focus on the composition, stability, and interaction of organic compounds in natural geothermal fluids.
Associated: Prof. Dr. Thorsten Schäfer, Alessio Leins (GFZ Potsdam)
Project: REFLECTExternal link (GFZ Potsdam)